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Diffstat (limited to 'arch/tile/kernel/intvec_32.S')
| -rw-r--r-- | arch/tile/kernel/intvec_32.S | 1920 |
1 files changed, 1920 insertions, 0 deletions
diff --git a/arch/tile/kernel/intvec_32.S b/arch/tile/kernel/intvec_32.S new file mode 100644 index 000000000..cdbda45a4 --- /dev/null +++ b/arch/tile/kernel/intvec_32.S @@ -0,0 +1,1920 @@ +/* + * Copyright 2010 Tilera Corporation. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + * + * Linux interrupt vectors. + */ + +#include <linux/linkage.h> +#include <linux/errno.h> +#include <linux/init.h> +#include <linux/unistd.h> +#include <asm/ptrace.h> +#include <asm/thread_info.h> +#include <asm/irqflags.h> +#include <asm/atomic_32.h> +#include <asm/asm-offsets.h> +#include <hv/hypervisor.h> +#include <arch/abi.h> +#include <arch/interrupts.h> +#include <arch/spr_def.h> + +#define PTREGS_PTR(reg, ptreg) addli reg, sp, C_ABI_SAVE_AREA_SIZE + (ptreg) + +#define PTREGS_OFFSET_SYSCALL PTREGS_OFFSET_REG(TREG_SYSCALL_NR) + + .macro push_reg reg, ptr=sp, delta=-4 + { + sw \ptr, \reg + addli \ptr, \ptr, \delta + } + .endm + + .macro pop_reg reg, ptr=sp, delta=4 + { + lw \reg, \ptr + addli \ptr, \ptr, \delta + } + .endm + + .macro pop_reg_zero reg, zreg, ptr=sp, delta=4 + { + move \zreg, zero + lw \reg, \ptr + addi \ptr, \ptr, \delta + } + .endm + + .macro push_extra_callee_saves reg + PTREGS_PTR(\reg, PTREGS_OFFSET_REG(51)) + push_reg r51, \reg + push_reg r50, \reg + push_reg r49, \reg + push_reg r48, \reg + push_reg r47, \reg + push_reg r46, \reg + push_reg r45, \reg + push_reg r44, \reg + push_reg r43, \reg + push_reg r42, \reg + push_reg r41, \reg + push_reg r40, \reg + push_reg r39, \reg + push_reg r38, \reg + push_reg r37, \reg + push_reg r36, \reg + push_reg r35, \reg + push_reg r34, \reg, PTREGS_OFFSET_BASE - PTREGS_OFFSET_REG(34) + .endm + + .macro panic str + .pushsection .rodata, "a" +1: + .asciz "\str" + .popsection + { + moveli r0, lo16(1b) + } + { + auli r0, r0, ha16(1b) + jal panic + } + .endm + +#ifdef __COLLECT_LINKER_FEEDBACK__ + .pushsection .text.intvec_feedback,"ax" +intvec_feedback: + .popsection +#endif + + /* + * Default interrupt handler. + * + * vecnum is where we'll put this code. + * c_routine is the C routine we'll call. + * + * The C routine is passed two arguments: + * - A pointer to the pt_regs state. + * - The interrupt vector number. + * + * The "processing" argument specifies the code for processing + * the interrupt. Defaults to "handle_interrupt". + */ + .macro int_hand vecnum, vecname, c_routine, processing=handle_interrupt + .org (\vecnum << 8) +intvec_\vecname: + .ifc \vecnum, INT_SWINT_1 + blz TREG_SYSCALL_NR_NAME, sys_cmpxchg + .endif + + /* Temporarily save a register so we have somewhere to work. */ + + mtspr SPR_SYSTEM_SAVE_K_1, r0 + mfspr r0, SPR_EX_CONTEXT_K_1 + + /* The cmpxchg code clears sp to force us to reset it here on fault. */ + { + bz sp, 2f + andi r0, r0, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */ + } + + .ifc \vecnum, INT_DOUBLE_FAULT + /* + * For double-faults from user-space, fall through to the normal + * register save and stack setup path. Otherwise, it's the + * hypervisor giving us one last chance to dump diagnostics, and we + * branch to the kernel_double_fault routine to do so. + */ + bz r0, 1f + j _kernel_double_fault +1: + .else + /* + * If we're coming from user-space, then set sp to the top of + * the kernel stack. Otherwise, assume sp is already valid. + */ + { + bnz r0, 0f + move r0, sp + } + .endif + + .ifc \c_routine, do_page_fault + /* + * The page_fault handler may be downcalled directly by the + * hypervisor even when Linux is running and has ICS set. + * + * In this case the contents of EX_CONTEXT_K_1 reflect the + * previous fault and can't be relied on to choose whether or + * not to reinitialize the stack pointer. So we add a test + * to see whether SYSTEM_SAVE_K_2 has the high bit set, + * and if so we don't reinitialize sp, since we must be coming + * from Linux. (In fact the precise case is !(val & ~1), + * but any Linux PC has to have the high bit set.) + * + * Note that the hypervisor *always* sets SYSTEM_SAVE_K_2 for + * any path that turns into a downcall to one of our TLB handlers. + */ + mfspr r0, SPR_SYSTEM_SAVE_K_2 + { + blz r0, 0f /* high bit in S_S_1_2 is for a PC to use */ + move r0, sp + } + .endif + +2: + /* + * SYSTEM_SAVE_K_0 holds the cpu number in the low bits, and + * the current stack top in the higher bits. So we recover + * our stack top by just masking off the low bits, then + * point sp at the top aligned address on the actual stack page. + */ + mfspr r0, SPR_SYSTEM_SAVE_K_0 + mm r0, r0, zero, LOG2_NR_CPU_IDS, 31 + +0: + /* + * Align the stack mod 64 so we can properly predict what + * cache lines we need to write-hint to reduce memory fetch + * latency as we enter the kernel. The layout of memory is + * as follows, with cache line 0 at the lowest VA, and cache + * line 4 just below the r0 value this "andi" computes. + * Note that we never write to cache line 4, and we skip + * cache line 1 for syscalls. + * + * cache line 4: ptregs padding (two words) + * cache line 3: r46...lr, pc, ex1, faultnum, orig_r0, flags, pad + * cache line 2: r30...r45 + * cache line 1: r14...r29 + * cache line 0: 2 x frame, r0..r13 + */ +#if STACK_TOP_DELTA != 64 +#error STACK_TOP_DELTA must be 64 for assumptions here and in task_pt_regs() +#endif + andi r0, r0, -64 + + /* + * Push the first four registers on the stack, so that we can set + * them to vector-unique values before we jump to the common code. + * + * Registers are pushed on the stack as a struct pt_regs, + * with the sp initially just above the struct, and when we're + * done, sp points to the base of the struct, minus + * C_ABI_SAVE_AREA_SIZE, so we can directly jal to C code. + * + * This routine saves just the first four registers, plus the + * stack context so we can do proper backtracing right away, + * and defers to handle_interrupt to save the rest. + * The backtracer needs pc, ex1, lr, sp, r52, and faultnum. + */ + addli r0, r0, PTREGS_OFFSET_LR - (PTREGS_SIZE + KSTK_PTREGS_GAP) + wh64 r0 /* cache line 3 */ + { + sw r0, lr + addli r0, r0, PTREGS_OFFSET_SP - PTREGS_OFFSET_LR + } + { + sw r0, sp + addli sp, r0, PTREGS_OFFSET_REG(52) - PTREGS_OFFSET_SP + } + { + sw sp, r52 + addli sp, sp, PTREGS_OFFSET_REG(1) - PTREGS_OFFSET_REG(52) + } + wh64 sp /* cache line 0 */ + { + sw sp, r1 + addli sp, sp, PTREGS_OFFSET_REG(2) - PTREGS_OFFSET_REG(1) + } + { + sw sp, r2 + addli sp, sp, PTREGS_OFFSET_REG(3) - PTREGS_OFFSET_REG(2) + } + { + sw sp, r3 + addli sp, sp, PTREGS_OFFSET_PC - PTREGS_OFFSET_REG(3) + } + mfspr r0, SPR_EX_CONTEXT_K_0 + .ifc \processing,handle_syscall + /* + * Bump the saved PC by one bundle so that when we return, we won't + * execute the same swint instruction again. We need to do this while + * we're in the critical section. + */ + addi r0, r0, 8 + .endif + { + sw sp, r0 + addli sp, sp, PTREGS_OFFSET_EX1 - PTREGS_OFFSET_PC + } + mfspr r0, SPR_EX_CONTEXT_K_1 + { + sw sp, r0 + addi sp, sp, PTREGS_OFFSET_FAULTNUM - PTREGS_OFFSET_EX1 + /* + * Use r0 for syscalls so it's a temporary; use r1 for interrupts + * so that it gets passed through unchanged to the handler routine. + * Note that the .if conditional confusingly spans bundles. + */ + .ifc \processing,handle_syscall + movei r0, \vecnum + } + { + sw sp, r0 + .else + movei r1, \vecnum + } + { + sw sp, r1 + .endif + addli sp, sp, PTREGS_OFFSET_REG(0) - PTREGS_OFFSET_FAULTNUM + } + mfspr r0, SPR_SYSTEM_SAVE_K_1 /* Original r0 */ + { + sw sp, r0 + addi sp, sp, -PTREGS_OFFSET_REG(0) - 4 + } + { + sw sp, zero /* write zero into "Next SP" frame pointer */ + addi sp, sp, -4 /* leave SP pointing at bottom of frame */ + } + .ifc \processing,handle_syscall + j handle_syscall + .else + /* + * Capture per-interrupt SPR context to registers. + * We overload the meaning of r3 on this path such that if its bit 31 + * is set, we have to mask all interrupts including NMIs before + * clearing the interrupt critical section bit. + * See discussion below at "finish_interrupt_save". + */ + .ifc \c_routine, do_page_fault + mfspr r2, SPR_SYSTEM_SAVE_K_3 /* address of page fault */ + mfspr r3, SPR_SYSTEM_SAVE_K_2 /* info about page fault */ + .else + .ifc \vecnum, INT_DOUBLE_FAULT + { + mfspr r2, SPR_SYSTEM_SAVE_K_2 /* double fault info from HV */ + movei r3, 0 + } + .else + .ifc \c_routine, do_trap + { + mfspr r2, GPV_REASON + movei r3, 0 + } + .else + .ifc \c_routine, handle_perf_interrupt + { + mfspr r2, PERF_COUNT_STS + movei r3, -1 /* not used, but set for consistency */ + } + .else + .ifc \c_routine, handle_perf_interrupt + { + mfspr r2, AUX_PERF_COUNT_STS + movei r3, -1 /* not used, but set for consistency */ + } + .else + movei r3, 0 + .endif + .endif + .endif + .endif + .endif + /* Put function pointer in r0 */ + moveli r0, lo16(\c_routine) + { + auli r0, r0, ha16(\c_routine) + j \processing + } + .endif + ENDPROC(intvec_\vecname) + +#ifdef __COLLECT_LINKER_FEEDBACK__ + .pushsection .text.intvec_feedback,"ax" + .org (\vecnum << 5) + FEEDBACK_ENTER_EXPLICIT(intvec_\vecname, .intrpt, 1 << 8) + jrp lr + .popsection +#endif + + .endm + + + /* + * Save the rest of the registers that we didn't save in the actual + * vector itself. We can't use r0-r10 inclusive here. + */ + .macro finish_interrupt_save, function + + /* If it's a syscall, save a proper orig_r0, otherwise just zero. */ + PTREGS_PTR(r52, PTREGS_OFFSET_ORIG_R0) + { + .ifc \function,handle_syscall + sw r52, r0 + .else + sw r52, zero + .endif + PTREGS_PTR(r52, PTREGS_OFFSET_TP) + } + + /* + * For ordinary syscalls, we save neither caller- nor callee- + * save registers, since the syscall invoker doesn't expect the + * caller-saves to be saved, and the called kernel functions will + * take care of saving the callee-saves for us. + * + * For interrupts we save just the caller-save registers. Saving + * them is required (since the "caller" can't save them). Again, + * the called kernel functions will restore the callee-save + * registers for us appropriately. + * + * On return, we normally restore nothing special for syscalls, + * and just the caller-save registers for interrupts. + * + * However, there are some important caveats to all this: + * + * - We always save a few callee-save registers to give us + * some scratchpad registers to carry across function calls. + * + * - fork/vfork/etc require us to save all the callee-save + * registers, which we do in PTREGS_SYSCALL_ALL_REGS, below. + * + * - We always save r0..r5 and r10 for syscalls, since we need + * to reload them a bit later for the actual kernel call, and + * since we might need them for -ERESTARTNOINTR, etc. + * + * - Before invoking a signal handler, we save the unsaved + * callee-save registers so they are visible to the + * signal handler or any ptracer. + * + * - If the unsaved callee-save registers are modified, we set + * a bit in pt_regs so we know to reload them from pt_regs + * and not just rely on the kernel function unwinding. + * (Done for ptrace register writes and SA_SIGINFO handler.) + */ + { + sw r52, tp + PTREGS_PTR(r52, PTREGS_OFFSET_REG(33)) + } + wh64 r52 /* cache line 2 */ + push_reg r33, r52 + push_reg r32, r52 + push_reg r31, r52 + .ifc \function,handle_syscall + push_reg r30, r52, PTREGS_OFFSET_SYSCALL - PTREGS_OFFSET_REG(30) + push_reg TREG_SYSCALL_NR_NAME, r52, \ + PTREGS_OFFSET_REG(5) - PTREGS_OFFSET_SYSCALL + .else + + push_reg r30, r52, PTREGS_OFFSET_REG(29) - PTREGS_OFFSET_REG(30) + wh64 r52 /* cache line 1 */ + push_reg r29, r52 + push_reg r28, r52 + push_reg r27, r52 + push_reg r26, r52 + push_reg r25, r52 + push_reg r24, r52 + push_reg r23, r52 + push_reg r22, r52 + push_reg r21, r52 + push_reg r20, r52 + push_reg r19, r52 + push_reg r18, r52 + push_reg r17, r52 + push_reg r16, r52 + push_reg r15, r52 + push_reg r14, r52 + push_reg r13, r52 + push_reg r12, r52 + push_reg r11, r52 + push_reg r10, r52 + push_reg r9, r52 + push_reg r8, r52 + push_reg r7, r52 + push_reg r6, r52 + + .endif + + push_reg r5, r52 + sw r52, r4 + + /* Load tp with our per-cpu offset. */ +#ifdef CONFIG_SMP + { + mfspr r20, SPR_SYSTEM_SAVE_K_0 + moveli r21, lo16(__per_cpu_offset) + } + { + auli r21, r21, ha16(__per_cpu_offset) + mm r20, r20, zero, 0, LOG2_NR_CPU_IDS-1 + } + s2a r20, r20, r21 + lw tp, r20 +#else + move tp, zero +#endif + + /* + * If we will be returning to the kernel, we will need to + * reset the interrupt masks to the state they had before. + * Set DISABLE_IRQ in flags iff we came from PL1 with irqs disabled. + * We load flags in r32 here so we can jump to .Lrestore_regs + * directly after do_page_fault_ics() if necessary. + */ + mfspr r32, SPR_EX_CONTEXT_K_1 + { + andi r32, r32, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */ + PTREGS_PTR(r21, PTREGS_OFFSET_FLAGS) + } + bzt r32, 1f /* zero if from user space */ + IRQS_DISABLED(r32) /* zero if irqs enabled */ +#if PT_FLAGS_DISABLE_IRQ != 1 +# error Value of IRQS_DISABLED used to set PT_FLAGS_DISABLE_IRQ; fix +#endif +1: + .ifnc \function,handle_syscall + /* Record the fact that we saved the caller-save registers above. */ + ori r32, r32, PT_FLAGS_CALLER_SAVES + .endif + sw r21, r32 + +#ifdef __COLLECT_LINKER_FEEDBACK__ + /* + * Notify the feedback routines that we were in the + * appropriate fixed interrupt vector area. Note that we + * still have ICS set at this point, so we can't invoke any + * atomic operations or we will panic. The feedback + * routines internally preserve r0..r10 and r30 up. + */ + .ifnc \function,handle_syscall + shli r20, r1, 5 + .else + moveli r20, INT_SWINT_1 << 5 + .endif + addli r20, r20, lo16(intvec_feedback) + auli r20, r20, ha16(intvec_feedback) + jalr r20 + + /* And now notify the feedback routines that we are here. */ + FEEDBACK_ENTER(\function) +#endif + + /* + * we've captured enough state to the stack (including in + * particular our EX_CONTEXT state) that we can now release + * the interrupt critical section and replace it with our + * standard "interrupts disabled" mask value. This allows + * synchronous interrupts (and profile interrupts) to punch + * through from this point onwards. + * + * If bit 31 of r3 is set during a non-NMI interrupt, we know we + * are on the path where the hypervisor has punched through our + * ICS with a page fault, so we call out to do_page_fault_ics() + * to figure out what to do with it. If the fault was in + * an atomic op, we unlock the atomic lock, adjust the + * saved register state a little, and return "zero" in r4, + * falling through into the normal page-fault interrupt code. + * If the fault was in a kernel-space atomic operation, then + * do_page_fault_ics() resolves it itself, returns "one" in r4, + * and as a result goes directly to restoring registers and iret, + * without trying to adjust the interrupt masks at all. + * The do_page_fault_ics() API involves passing and returning + * a five-word struct (in registers) to avoid writing the + * save and restore code here. + */ + .ifc \function,handle_nmi + IRQ_DISABLE_ALL(r20) + .else + .ifnc \function,handle_syscall + bgezt r3, 1f + { + PTREGS_PTR(r0, PTREGS_OFFSET_BASE) + jal do_page_fault_ics + } + FEEDBACK_REENTER(\function) + bzt r4, 1f + j .Lrestore_regs +1: + .endif + IRQ_DISABLE(r20, r21) + .endif + mtspr INTERRUPT_CRITICAL_SECTION, zero + + /* + * Prepare the first 256 stack bytes to be rapidly accessible + * without having to fetch the background data. We don't really + * know how far to write-hint, but kernel stacks generally + * aren't that big, and write-hinting here does take some time. + */ + addi r52, sp, -64 + { + wh64 r52 + addi r52, r52, -64 + } + { + wh64 r52 + addi r52, r52, -64 + } + { + wh64 r52 + addi r52, r52, -64 + } + wh64 r52 + +#ifdef CONFIG_TRACE_IRQFLAGS + .ifnc \function,handle_nmi + /* + * We finally have enough state set up to notify the irq + * tracing code that irqs were disabled on entry to the handler. + * The TRACE_IRQS_OFF call clobbers registers r0-r29. + * For syscalls, we already have the register state saved away + * on the stack, so we don't bother to do any register saves here, + * and later we pop the registers back off the kernel stack. + * For interrupt handlers, save r0-r3 in callee-saved registers. + */ + .ifnc \function,handle_syscall + { move r30, r0; move r31, r1 } + { move r32, r2; move r33, r3 } + .endif + TRACE_IRQS_OFF + .ifnc \function,handle_syscall + { move r0, r30; move r1, r31 } + { move r2, r32; move r3, r33 } + .endif + .endif +#endif + + .endm + + .macro check_single_stepping, kind, not_single_stepping + /* + * Check for single stepping in user-level priv + * kind can be "normal", "ill", or "syscall" + * At end, if fall-thru + * r29: thread_info->step_state + * r28: &pt_regs->pc + * r27: pt_regs->pc + * r26: thread_info->step_state->buffer + */ + + /* Check for single stepping */ + GET_THREAD_INFO(r29) + { + /* Get pointer to field holding step state */ + addi r29, r29, THREAD_INFO_STEP_STATE_OFFSET + + /* Get pointer to EX1 in register state */ + PTREGS_PTR(r27, PTREGS_OFFSET_EX1) + } + { + /* Get pointer to field holding PC */ + PTREGS_PTR(r28, PTREGS_OFFSET_PC) + + /* Load the pointer to the step state */ + lw r29, r29 + } + /* Load EX1 */ + lw r27, r27 + { + /* Points to flags */ + addi r23, r29, SINGLESTEP_STATE_FLAGS_OFFSET + + /* No single stepping if there is no step state structure */ + bzt r29, \not_single_stepping + } + { + /* mask off ICS and any other high bits */ + andi r27, r27, SPR_EX_CONTEXT_1_1__PL_MASK + + /* Load pointer to single step instruction buffer */ + lw r26, r29 + } + /* Check priv state */ + bnz r27, \not_single_stepping + + /* Get flags */ + lw r22, r23 + { + /* Branch if single-step mode not enabled */ + bbnst r22, \not_single_stepping + + /* Clear enabled flag */ + andi r22, r22, ~SINGLESTEP_STATE_MASK_IS_ENABLED + } + .ifc \kind,normal + { + /* Load PC */ + lw r27, r28 + + /* Point to the entry containing the original PC */ + addi r24, r29, SINGLESTEP_STATE_ORIG_PC_OFFSET + } + { + /* Disable single stepping flag */ + sw r23, r22 + } + { + /* Get the original pc */ + lw r24, r24 + + /* See if the PC is at the start of the single step buffer */ + seq r25, r26, r27 + } + /* + * NOTE: it is really expected that the PC be in the single step buffer + * at this point + */ + bzt r25, \not_single_stepping + + /* Restore the original PC */ + sw r28, r24 + .else + .ifc \kind,syscall + { + /* Load PC */ + lw r27, r28 + + /* Point to the entry containing the next PC */ + addi r24, r29, SINGLESTEP_STATE_NEXT_PC_OFFSET + } + { + /* Increment the stopped PC by the bundle size */ + addi r26, r26, 8 + + /* Disable single stepping flag */ + sw r23, r22 + } + { + /* Get the next pc */ + lw r24, r24 + + /* + * See if the PC is one bundle past the start of the + * single step buffer + */ + seq r25, r26, r27 + } + { + /* + * NOTE: it is really expected that the PC be in the + * single step buffer at this point + */ + bzt r25, \not_single_stepping + } + /* Set to the next PC */ + sw r28, r24 + .else + { + /* Point to 3rd bundle in buffer */ + addi r25, r26, 16 + + /* Load PC */ + lw r27, r28 + } + { + /* Disable single stepping flag */ + sw r23, r22 + + /* See if the PC is in the single step buffer */ + slte_u r24, r26, r27 + } + { + slte_u r25, r27, r25 + + /* + * NOTE: it is really expected that the PC be in the + * single step buffer at this point + */ + bzt r24, \not_single_stepping + } + bzt r25, \not_single_stepping + .endif + .endif + .endm + + /* + * Redispatch a downcall. + */ + .macro dc_dispatch vecnum, vecname + .org (\vecnum << 8) +intvec_\vecname: + j _hv_downcall_dispatch + ENDPROC(intvec_\vecname) + .endm + + /* + * Common code for most interrupts. The C function we're eventually + * going to is in r0, and the faultnum is in r1; the original + * values for those registers are on the stack. + */ + .pushsection .text.handle_interrupt,"ax" +handle_interrupt: + finish_interrupt_save handle_interrupt + + /* + * Check for if we are single stepping in user level. If so, then + * we need to restore the PC. + */ + + check_single_stepping normal, .Ldispatch_interrupt +.Ldispatch_interrupt: + + /* Jump to the C routine; it should enable irqs as soon as possible. */ + { + jalr r0 + PTREGS_PTR(r0, PTREGS_OFFSET_BASE) + } + FEEDBACK_REENTER(handle_interrupt) + { + movei r30, 0 /* not an NMI */ + j interrupt_return + } + STD_ENDPROC(handle_interrupt) + +/* + * This routine takes a boolean in r30 indicating if this is an NMI. + * If so, we also expect a boolean in r31 indicating whether to + * re-enable the oprofile interrupts. + * + * Note that .Lresume_userspace is jumped to directly in several + * places, and we need to make sure r30 is set correctly in those + * callers as well. + */ +STD_ENTRY(interrupt_return) + /* If we're resuming to kernel space, don't check thread flags. */ + { + bnz r30, .Lrestore_all /* NMIs don't special-case user-space */ + PTREGS_PTR(r29, PTREGS_OFFSET_EX1) + } + lw r29, r29 + andi r29, r29, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */ + bzt r29, .Lresume_userspace + +#ifdef CONFIG_PREEMPT + /* Returning to kernel space. Check if we need preemption. */ + GET_THREAD_INFO(r29) + addli r28, r29, THREAD_INFO_FLAGS_OFFSET + { + lw r28, r28 + addli r29, r29, THREAD_INFO_PREEMPT_COUNT_OFFSET + } + { + andi r28, r28, _TIF_NEED_RESCHED + lw r29, r29 + } + bzt r28, 1f + bnz r29, 1f + /* Disable interrupts explicitly for preemption. */ + IRQ_DISABLE(r20,r21) + TRACE_IRQS_OFF + jal preempt_schedule_irq + FEEDBACK_REENTER(interrupt_return) +1: +#endif + + /* If we're resuming to _cpu_idle_nap, bump PC forward by 8. */ + { + PTREGS_PTR(r29, PTREGS_OFFSET_PC) + moveli r27, lo16(_cpu_idle_nap) + } + { + lw r28, r29 + auli r27, r27, ha16(_cpu_idle_nap) + } + { + seq r27, r27, r28 + } + { + bbns r27, .Lrestore_all + addi r28, r28, 8 + } + sw r29, r28 + j .Lrestore_all + +.Lresume_userspace: + FEEDBACK_REENTER(interrupt_return) + + /* + * Use r33 to hold whether we have already loaded the callee-saves + * into ptregs. We don't want to do it twice in this loop, since + * then we'd clobber whatever changes are made by ptrace, etc. + * Get base of stack in r32. + */ + { + GET_THREAD_INFO(r32) + movei r33, 0 + } + +.Lretry_work_pending: + /* + * Disable interrupts so as to make sure we don't + * miss an interrupt that sets any of the thread flags (like + * need_resched or sigpending) between sampling and the iret. + * Routines like schedule() or do_signal() may re-enable + * interrupts before returning. + */ + IRQ_DISABLE(r20, r21) + TRACE_IRQS_OFF /* Note: clobbers registers r0-r29 */ + + + /* Check to see if there is any work to do before returning to user. */ + { + addi r29, r32, THREAD_INFO_FLAGS_OFFSET + moveli r1, lo16(_TIF_ALLWORK_MASK) + } + { + lw r29, r29 + auli r1, r1, ha16(_TIF_ALLWORK_MASK) + } + and r1, r29, r1 + bzt r1, .Lrestore_all + + /* + * Make sure we have all the registers saved for signal + * handling, notify-resume, or single-step. Call out to C + * code to figure out exactly what we need to do for each flag bit, + * then if necessary, reload the flags and recheck. + */ + { + PTREGS_PTR(r0, PTREGS_OFFSET_BASE) + bnz r33, 1f + } + push_extra_callee_saves r0 + movei r33, 1 +1: jal do_work_pending + bnz r0, .Lretry_work_pending + + /* + * In the NMI case we + * omit the call to single_process_check_nohz, which normally checks + * to see if we should start or stop the scheduler tick, because + * we can't call arbitrary Linux code from an NMI context. + * We always call the homecache TLB deferral code to re-trigger + * the deferral mechanism. + * + * The other chunk of responsibility this code has is to reset the + * interrupt masks appropriately to reset irqs and NMIs. We have + * to call TRACE_IRQS_OFF and TRACE_IRQS_ON to support all the + * lockdep-type stuff, but we can't set ICS until afterwards, since + * ICS can only be used in very tight chunks of code to avoid + * tripping over various assertions that it is off. + * + * (There is what looks like a window of vulnerability here since + * we might take a profile interrupt between the two SPR writes + * that set the mask, but since we write the low SPR word first, + * and our interrupt entry code checks the low SPR word, any + * profile interrupt will actually disable interrupts in both SPRs + * before returning, which is OK.) + */ +.Lrestore_all: + PTREGS_PTR(r0, PTREGS_OFFSET_EX1) + { + lw r0, r0 + PTREGS_PTR(r32, PTREGS_OFFSET_FLAGS) + } + { + andi r0, r0, SPR_EX_CONTEXT_1_1__PL_MASK + lw r32, r32 + } + bnz r0, 1f + j 2f +#if PT_FLAGS_DISABLE_IRQ != 1 +# error Assuming PT_FLAGS_DISABLE_IRQ == 1 so we can use bbnst below +#endif +1: bbnst r32, 2f + IRQ_DISABLE(r20,r21) + TRACE_IRQS_OFF + movei r0, 1 + mtspr INTERRUPT_CRITICAL_SECTION, r0 + bzt r30, .Lrestore_regs + j 3f +2: TRACE_IRQS_ON + movei r0, 1 + mtspr INTERRUPT_CRITICAL_SECTION, r0 + IRQ_ENABLE(r20, r21) + bzt r30, .Lrestore_regs +3: + + /* We are relying on INT_PERF_COUNT at 33, and AUX_PERF_COUNT at 48 */ + { + moveli r0, lo16(1 << (INT_PERF_COUNT - 32)) + bz r31, .Lrestore_regs + } + auli r0, r0, ha16(1 << (INT_AUX_PERF_COUNT - 32)) + mtspr SPR_INTERRUPT_MASK_RESET_K_1, r0 + + /* + * We now commit to returning from this interrupt, since we will be + * doing things like setting EX_CONTEXT SPRs and unwinding the stack + * frame. No calls should be made to any other code after this point. + * This code should only be entered with ICS set. + * r32 must still be set to ptregs.flags. + * We launch loads to each cache line separately first, so we can + * get some parallelism out of the memory subsystem. + * We start zeroing caller-saved registers throughout, since + * that will save some cycles if this turns out to be a syscall. + */ +.Lrestore_regs: + FEEDBACK_REENTER(interrupt_return) /* called from elsewhere */ + + /* + * Rotate so we have one high bit and one low bit to test. + * - low bit says whether to restore all the callee-saved registers, + * or just r30-r33, and r52 up. + * - high bit (i.e. sign bit) says whether to restore all the + * caller-saved registers, or just r0. + */ +#if PT_FLAGS_CALLER_SAVES != 2 || PT_FLAGS_RESTORE_REGS != 4 +# error Rotate trick does not work :-) +#endif + { + rli r20, r32, 30 + PTREGS_PTR(sp, PTREGS_OFFSET_REG(0)) + } + + /* + * Load cache lines 0, 2, and 3 in that order, then use + * the last loaded value, which makes it likely that the other + * cache lines have also loaded, at which point we should be + * able to safely read all the remaining words on those cache + * lines without waiting for the memory subsystem. + */ + pop_reg_zero r0, r28, sp, PTREGS_OFFSET_REG(30) - PTREGS_OFFSET_REG(0) + pop_reg_zero r30, r2, sp, PTREGS_OFFSET_PC - PTREGS_OFFSET_REG(30) + pop_reg_zero r21, r3, sp, PTREGS_OFFSET_EX1 - PTREGS_OFFSET_PC + pop_reg_zero lr, r4, sp, PTREGS_OFFSET_REG(52) - PTREGS_OFFSET_EX1 + { + mtspr SPR_EX_CONTEXT_K_0, r21 + move r5, zero + } + { + mtspr SPR_EX_CONTEXT_K_1, lr + andi lr, lr, SPR_EX_CONTEXT_1_1__PL_MASK /* mask off ICS */ + } + + /* Restore callee-saveds that we actually use. */ + pop_reg_zero r52, r6, sp, PTREGS_OFFSET_REG(31) - PTREGS_OFFSET_REG(52) + pop_reg_zero r31, r7 + pop_reg_zero r32, r8 + pop_reg_zero r33, r9, sp, PTREGS_OFFSET_REG(29) - PTREGS_OFFSET_REG(33) + + /* + * If we modified other callee-saveds, restore them now. + * This is rare, but could be via ptrace or signal handler. + */ + { + move r10, zero + bbs r20, .Lrestore_callees + } +.Lcontinue_restore_regs: + + /* Check if we're returning from a syscall. */ + { + move r11, zero + blzt r20, 1f /* no, so go restore callee-save registers */ + } + + /* + * Check if we're returning to userspace. + * Note that if we're not, we don't worry about zeroing everything. + */ + { + addli sp, sp, PTREGS_OFFSET_LR - PTREGS_OFFSET_REG(29) + bnz lr, .Lkernel_return + } + + /* + * On return from syscall, we've restored r0 from pt_regs, but we + * clear the remainder of the caller-saved registers. We could + * restore the syscall arguments, but there's not much point, + * and it ensures user programs aren't trying to use the + * caller-saves if we clear them, as well as avoiding leaking + * kernel pointers into userspace. + */ + pop_reg_zero lr, r12, sp, PTREGS_OFFSET_TP - PTREGS_OFFSET_LR + pop_reg_zero tp, r13, sp, PTREGS_OFFSET_SP - PTREGS_OFFSET_TP + { + lw sp, sp + move r14, zero + move r15, zero + } + { move r16, zero; move r17, zero } + { move r18, zero; move r19, zero } + { move r20, zero; move r21, zero } + { move r22, zero; move r23, zero } + { move r24, zero; move r25, zero } + { move r26, zero; move r27, zero } + + /* Set r1 to errno if we are returning an error, otherwise zero. */ + { + moveli r29, 4096 + sub r1, zero, r0 + } + slt_u r29, r1, r29 + { + mnz r1, r29, r1 + move r29, zero + } + iret + + /* + * Not a syscall, so restore caller-saved registers. + * First kick off a load for cache line 1, which we're touching + * for the first time here. + */ + .align 64 +1: pop_reg r29, sp, PTREGS_OFFSET_REG(1) - PTREGS_OFFSET_REG(29) + pop_reg r1 + pop_reg r2 + pop_reg r3 + pop_reg r4 + pop_reg r5 + pop_reg r6 + pop_reg r7 + pop_reg r8 + pop_reg r9 + pop_reg r10 + pop_reg r11 + pop_reg r12 + pop_reg r13 + pop_reg r14 + pop_reg r15 + pop_reg r16 + pop_reg r17 + pop_reg r18 + pop_reg r19 + pop_reg r20 + pop_reg r21 + pop_reg r22 + pop_reg r23 + pop_reg r24 + pop_reg r25 + pop_reg r26 + pop_reg r27 + pop_reg r28, sp, PTREGS_OFFSET_LR - PTREGS_OFFSET_REG(28) + /* r29 already restored above */ + bnz lr, .Lkernel_return + pop_reg lr, sp, PTREGS_OFFSET_TP - PTREGS_OFFSET_LR + pop_reg tp, sp, PTREGS_OFFSET_SP - PTREGS_OFFSET_TP + lw sp, sp + iret + + /* + * We can't restore tp when in kernel mode, since a thread might + * have migrated from another cpu and brought a stale tp value. + */ +.Lkernel_return: + pop_reg lr, sp, PTREGS_OFFSET_SP - PTREGS_OFFSET_LR + lw sp, sp + iret + + /* Restore callee-saved registers from r34 to r51. */ +.Lrestore_callees: + addli sp, sp, PTREGS_OFFSET_REG(34) - PTREGS_OFFSET_REG(29) + pop_reg r34 + pop_reg r35 + pop_reg r36 + pop_reg r37 + pop_reg r38 + pop_reg r39 + pop_reg r40 + pop_reg r41 + pop_reg r42 + pop_reg r43 + pop_reg r44 + pop_reg r45 + pop_reg r46 + pop_reg r47 + pop_reg r48 + pop_reg r49 + pop_reg r50 + pop_reg r51, sp, PTREGS_OFFSET_REG(29) - PTREGS_OFFSET_REG(51) + j .Lcontinue_restore_regs + STD_ENDPROC(interrupt_return) + + /* + * Some interrupts don't check for single stepping + */ + .pushsection .text.handle_interrupt_no_single_step,"ax" +handle_interrupt_no_single_step: + finish_interrupt_save handle_interrupt_no_single_step + { + jalr r0 + PTREGS_PTR(r0, PTREGS_OFFSET_BASE) + } + FEEDBACK_REENTER(handle_interrupt_no_single_step) + { + movei r30, 0 /* not an NMI */ + j interrupt_return + } + STD_ENDPROC(handle_interrupt_no_single_step) + + /* + * "NMI" interrupts mask ALL interrupts before calling the + * handler, and don't check thread flags, etc., on the way + * back out. In general, the only things we do here for NMIs + * are the register save/restore, fixing the PC if we were + * doing single step, and the dataplane kernel-TLB management. + * We don't (for example) deal with start/stop of the sched tick. + */ + .pushsection .text.handle_nmi,"ax" +handle_nmi: + finish_interrupt_save handle_nmi + check_single_stepping normal, .Ldispatch_nmi +.Ldispatch_nmi: + { + jalr r0 + PTREGS_PTR(r0, PTREGS_OFFSET_BASE) + } + FEEDBACK_REENTER(handle_nmi) + { + movei r30, 1 + seq r31, r0, zero + } + j interrupt_return + STD_ENDPROC(handle_nmi) + + /* + * Parallel code for syscalls to handle_interrupt. + */ + .pushsection .text.handle_syscall,"ax" +handle_syscall: + finish_interrupt_save handle_syscall + + /* + * Check for if we are single stepping in user level. If so, then + * we need to restore the PC. + */ + check_single_stepping syscall, .Ldispatch_syscall +.Ldispatch_syscall: + + /* Enable irqs. */ + TRACE_IRQS_ON + IRQ_ENABLE(r20, r21) + + /* Bump the counter for syscalls made on this tile. */ + moveli r20, lo16(irq_stat + IRQ_CPUSTAT_SYSCALL_COUNT_OFFSET) + auli r20, r20, ha16(irq_stat + IRQ_CPUSTAT_SYSCALL_COUNT_OFFSET) + add r20, r20, tp + lw r21, r20 + addi r21, r21, 1 + { + sw r20, r21 + GET_THREAD_INFO(r31) + } + + /* Trace syscalls, if requested. */ + addi r31, r31, THREAD_INFO_FLAGS_OFFSET + lw r30, r31 + andi r30, r30, _TIF_SYSCALL_TRACE + bzt r30, .Lrestore_syscall_regs + { + PTREGS_PTR(r0, PTREGS_OFFSET_BASE) + jal do_syscall_trace_enter + } + FEEDBACK_REENTER(handle_syscall) + + /* + * We always reload our registers from the stack at this + * point. They might be valid, if we didn't build with + * TRACE_IRQFLAGS, and this isn't a dataplane tile, and we're not + * doing syscall tracing, but there are enough cases now that it + * seems simplest just to do the reload unconditionally. + */ +.Lrestore_syscall_regs: + PTREGS_PTR(r11, PTREGS_OFFSET_REG(0)) + pop_reg r0, r11 + pop_reg r1, r11 + pop_reg r2, r11 + pop_reg r3, r11 + pop_reg r4, r11 + pop_reg r5, r11, PTREGS_OFFSET_SYSCALL - PTREGS_OFFSET_REG(5) + pop_reg TREG_SYSCALL_NR_NAME, r11 + + /* Ensure that the syscall number is within the legal range. */ + moveli r21, __NR_syscalls + { + slt_u r21, TREG_SYSCALL_NR_NAME, r21 + moveli r20, lo16(sys_call_table) + } + { + bbns r21, .Linvalid_syscall + auli r20, r20, ha16(sys_call_table) + } + s2a r20, TREG_SYSCALL_NR_NAME, r20 + lw r20, r20 + + /* Jump to syscall handler. */ + jalr r20 +.Lhandle_syscall_link: /* value of "lr" after "jalr r20" above */ + + /* + * Write our r0 onto the stack so it gets restored instead + * of whatever the user had there before. + */ + PTREGS_PTR(r29, PTREGS_OFFSET_REG(0)) + sw r29, r0 + +.Lsyscall_sigreturn_skip: + FEEDBACK_REENTER(handle_syscall) + + /* Do syscall trace again, if requested. */ + lw r30, r31 + andi r30, r30, _TIF_SYSCALL_TRACE + bzt r30, 1f + { + PTREGS_PTR(r0, PTREGS_OFFSET_BASE) + jal do_syscall_trace_exit + } + FEEDBACK_REENTER(handle_syscall) +1: { + movei r30, 0 /* not an NMI */ + j .Lresume_userspace /* jump into middle of interrupt_return */ + } + +.Linvalid_syscall: + /* Report an invalid syscall back to the user program */ + { + PTREGS_PTR(r29, PTREGS_OFFSET_REG(0)) + movei r28, -ENOSYS + } + sw r29, r28 + { + movei r30, 0 /* not an NMI */ + j .Lresume_userspace /* jump into middle of interrupt_return */ + } + STD_ENDPROC(handle_syscall) + + /* Return the address for oprofile to suppress in backtraces. */ +STD_ENTRY_SECTION(handle_syscall_link_address, .text.handle_syscall) + lnk r0 + { + addli r0, r0, .Lhandle_syscall_link - . + jrp lr + } + STD_ENDPROC(handle_syscall_link_address) + +STD_ENTRY(ret_from_fork) + jal sim_notify_fork + jal schedule_tail + FEEDBACK_REENTER(ret_from_fork) + { + movei r30, 0 /* not an NMI */ + j .Lresume_userspace /* jump into middle of interrupt_return */ + } + STD_ENDPROC(ret_from_fork) + +STD_ENTRY(ret_from_kernel_thread) + jal sim_notify_fork + jal schedule_tail + FEEDBACK_REENTER(ret_from_fork) + { + move r0, r31 + jalr r30 + } + FEEDBACK_REENTER(ret_from_kernel_thread) + { + movei r30, 0 /* not an NMI */ + j .Lresume_userspace /* jump into middle of interrupt_return */ + } + STD_ENDPROC(ret_from_kernel_thread) + + /* + * Code for ill interrupt. + */ + .pushsection .text.handle_ill,"ax" +handle_ill: + finish_interrupt_save handle_ill + + /* + * Check for if we are single stepping in user level. If so, then + * we need to restore the PC. + */ + check_single_stepping ill, .Ldispatch_normal_ill + + { + /* See if the PC is the 1st bundle in the buffer */ + seq r25, r27, r26 + + /* Point to the 2nd bundle in the buffer */ + addi r26, r26, 8 + } + { + /* Point to the original pc */ + addi r24, r29, SINGLESTEP_STATE_ORIG_PC_OFFSET + + /* Branch if the PC is the 1st bundle in the buffer */ + bnz r25, 3f + } + { + /* See if the PC is the 2nd bundle of the buffer */ + seq r25, r27, r26 + + /* Set PC to next instruction */ + addi r24, r29, SINGLESTEP_STATE_NEXT_PC_OFFSET + } + { + /* Point to flags */ + addi r25, r29, SINGLESTEP_STATE_FLAGS_OFFSET + + /* Branch if PC is in the second bundle */ + bz r25, 2f + } + /* Load flags */ + lw r25, r25 + { + /* + * Get the offset for the register to restore + * Note: the lower bound is 2, so we have implicit scaling by 4. + * No multiplication of the register number by the size of a register + * is needed. + */ + mm r27, r25, zero, SINGLESTEP_STATE_TARGET_LB, \ + SINGLESTEP_STATE_TARGET_UB + + /* Mask Rewrite_LR */ + andi r25, r25, SINGLESTEP_STATE_MASK_UPDATE + } + { + addi r29, r29, SINGLESTEP_STATE_UPDATE_VALUE_OFFSET + + /* Don't rewrite temp register */ + bz r25, 3f + } + { + /* Get the temp value */ + lw r29, r29 + + /* Point to where the register is stored */ + add r27, r27, sp + } + + /* Add in the C ABI save area size to the register offset */ + addi r27, r27, C_ABI_SAVE_AREA_SIZE + + /* Restore the user's register with the temp value */ + sw r27, r29 + j 3f + +2: + /* Must be in the third bundle */ + addi r24, r29, SINGLESTEP_STATE_BRANCH_NEXT_PC_OFFSET + +3: + /* set PC and continue */ + lw r26, r24 + { + sw r28, r26 + GET_THREAD_INFO(r0) + } + + /* + * Clear TIF_SINGLESTEP to prevent recursion if we execute an ill. + * The normal non-arch flow redundantly clears TIF_SINGLESTEP, but we + * need to clear it here and can't really impose on all other arches. + * So what's another write between friends? + */ + + addi r1, r0, THREAD_INFO_FLAGS_OFFSET + { + lw r2, r1 + addi r0, r0, THREAD_INFO_TASK_OFFSET /* currently a no-op */ + } + andi r2, r2, ~_TIF_SINGLESTEP + sw r1, r2 + + /* Issue a sigtrap */ + { + lw r0, r0 /* indirect thru thread_info to get task_info*/ + addi r1, sp, C_ABI_SAVE_AREA_SIZE /* put ptregs pointer into r1 */ + } + + jal send_sigtrap /* issue a SIGTRAP */ + FEEDBACK_REENTER(handle_ill) + { + movei r30, 0 /* not an NMI */ + j .Lresume_userspace /* jump into middle of interrupt_return */ + } + +.Ldispatch_normal_ill: + { + jalr r0 + PTREGS_PTR(r0, PTREGS_OFFSET_BASE) + } + FEEDBACK_REENTER(handle_ill) + { + movei r30, 0 /* not an NMI */ + j interrupt_return + } + STD_ENDPROC(handle_ill) + +/* Various stub interrupt handlers and syscall handlers */ + +STD_ENTRY_LOCAL(_kernel_double_fault) + mfspr r1, SPR_EX_CONTEXT_K_0 + move r2, lr + move r3, sp + move r4, r52 + addi sp, sp, -C_ABI_SAVE_AREA_SIZE + j kernel_double_fault + STD_ENDPROC(_kernel_double_fault) + +STD_ENTRY_LOCAL(bad_intr) + mfspr r2, SPR_EX_CONTEXT_K_0 + panic "Unhandled interrupt %#x: PC %#lx" + STD_ENDPROC(bad_intr) + +/* + * Special-case sigreturn to not write r0 to the stack on return. + * This is technically more efficient, but it also avoids difficulties + * in the 64-bit OS when handling 32-bit compat code, since we must not + * sign-extend r0 for the sigreturn return-value case. + */ +#define PTREGS_SYSCALL_SIGRETURN(x, reg) \ + STD_ENTRY(_##x); \ + addli lr, lr, .Lsyscall_sigreturn_skip - .Lhandle_syscall_link; \ + { \ + PTREGS_PTR(reg, PTREGS_OFFSET_BASE); \ + j x \ + }; \ + STD_ENDPROC(_##x) + +PTREGS_SYSCALL_SIGRETURN(sys_rt_sigreturn, r0) + +/* Save additional callee-saves to pt_regs and jump to standard function. */ +STD_ENTRY(_sys_clone) + push_extra_callee_saves r4 + j sys_clone + STD_ENDPROC(_sys_clone) + +/* + * This entrypoint is taken for the cmpxchg and atomic_update fast + * swints. We may wish to generalize it to other fast swints at some + * point, but for now there are just two very similar ones, which + * makes it faster. + * + * The fast swint code is designed to have a small footprint. It does + * not save or restore any GPRs, counting on the caller-save registers + * to be available to it on entry. It does not modify any callee-save + * registers (including "lr"). It does not check what PL it is being + * called at, so you'd better not call it other than at PL0. + * The <atomic.h> wrapper assumes it only clobbers r20-r29, so if + * it ever is necessary to use more registers, be aware. + * + * It does not use the stack, but since it might be re-interrupted by + * a page fault which would assume the stack was valid, it does + * save/restore the stack pointer and zero it out to make sure it gets reset. + * Since we always keep interrupts disabled, the hypervisor won't + * clobber our EX_CONTEXT_K_x registers, so we don't save/restore them + * (other than to advance the PC on return). + * + * We have to manually validate the user vs kernel address range + * (since at PL1 we can read/write both), and for performance reasons + * we don't allow cmpxchg on the fc000000 memory region, since we only + * validate that the user address is below PAGE_OFFSET. + * + * We place it in the __HEAD section to ensure it is relatively + * near to the intvec_SWINT_1 code (reachable by a conditional branch). + * + * Our use of ATOMIC_LOCK_REG here must match do_page_fault_ics(). + * + * As we do in lib/atomic_asm_32.S, we bypass a store if the value we + * would store is the same as the value we just loaded. + */ + __HEAD + .align 64 + /* Align much later jump on the start of a cache line. */ + nop +#if PAGE_SIZE >= 0x10000 + nop +#endif +ENTRY(sys_cmpxchg) + + /* + * Save "sp" and set it zero for any possible page fault. + * + * HACK: We want to both zero sp and check r0's alignment, + * so we do both at once. If "sp" becomes nonzero we + * know r0 is unaligned and branch to the error handler that + * restores sp, so this is OK. + * + * ICS is disabled right now so having a garbage but nonzero + * sp is OK, since we won't execute any faulting instructions + * when it is nonzero. + */ + { + move r27, sp + andi sp, r0, 3 + } + + /* + * Get the lock address in ATOMIC_LOCK_REG, and also validate that the + * address is less than PAGE_OFFSET, since that won't trap at PL1. + * We only use bits less than PAGE_SHIFT to avoid having to worry + * about aliasing among multiple mappings of the same physical page, + * and we ignore the low 3 bits so we have one lock that covers + * both a cmpxchg64() and a cmpxchg() on either its low or high word. + * NOTE: this must match __atomic_hashed_lock() in lib/atomic_32.c. + */ + +#if (PAGE_OFFSET & 0xffff) != 0 +# error Code here assumes PAGE_OFFSET can be loaded with just hi16() +#endif + + { + /* Check for unaligned input. */ + bnz sp, .Lcmpxchg_badaddr + auli r23, zero, hi16(PAGE_OFFSET) /* hugepage-aligned */ + } + { + /* + * Slide bits into position for 'mm'. We want to ignore + * the low 3 bits of r0, and consider only the next + * ATOMIC_HASH_SHIFT bits. + * Because of C pointer arithmetic, we want to compute this: + * + * ((char*)atomic_locks + + * (((r0 >> 3) & ((1 << ATOMIC_HASH_SHIFT) - 1)) << 2)) + * + * Instead of two shifts we just ">> 1", and use 'mm' + * to ignore the low and high bits we don't want. + */ + shri r25, r0, 1 + + slt_u r23, r0, r23 + + /* + * Ensure that the TLB is loaded before we take out the lock. + * This will start fetching the value all the way into our L1 + * as well (and if it gets modified before we grab the lock, + * it will be invalidated from our cache before we reload it). + */ + lw r26, r0 + } + { + auli r21, zero, ha16(atomic_locks) + + bbns r23, .Lcmpxchg_badaddr + } +#if PAGE_SIZE < 0x10000 + /* atomic_locks is page-aligned so for big pages we don't need this. */ + addli r21, r21, lo16(atomic_locks) +#endif + { + /* + * Insert the hash bits into the page-aligned pointer. + * ATOMIC_HASH_SHIFT is so big that we don't actually hash + * the unmasked address bits, as that may cause unnecessary + * collisions. + */ + mm ATOMIC_LOCK_REG_NAME, r25, r21, 2, (ATOMIC_HASH_SHIFT + 2) - 1 + + seqi r23, TREG_SYSCALL_NR_NAME, __NR_FAST_cmpxchg64 + } + { + /* Branch away at this point if we're doing a 64-bit cmpxchg. */ + bbs r23, .Lcmpxchg64 + andi r23, r0, 7 /* Precompute alignment for cmpxchg64. */ + } + { + /* + * We very carefully align the code that actually runs with + * the lock held (twelve bundles) so that we know it is all in + * the icache when we start. This instruction (the jump) is + * at the start of the first cache line, address zero mod 64; + * we jump to the very end of the second cache line to get that + * line loaded in the icache, then fall through to issue the tns + * in the third cache line, at which point it's all cached. + * Note that is for performance, not correctness. + */ + j .Lcmpxchg32_tns + } + +/* Symbol for do_page_fault_ics() to use to compare against the PC. */ +.global __sys_cmpxchg_grab_lock +__sys_cmpxchg_grab_lock: + + /* + * Perform the actual cmpxchg or atomic_update. + */ +.Ldo_cmpxchg32: + { + lw r21, r0 + seqi r23, TREG_SYSCALL_NR_NAME, __NR_FAST_atomic_update + move r24, r2 + } + { + seq r22, r21, r1 /* See if cmpxchg matches. */ + and r25, r21, r1 /* If atomic_update, compute (*mem & mask) */ + } + { + or r22, r22, r23 /* Skip compare branch for atomic_update. */ + add r25, r25, r2 /* Compute (*mem & mask) + addend. */ + } + { + mvnz r24, r23, r25 /* Use atomic_update value if appropriate. */ + bbns r22, .Lcmpxchg32_nostore + } + seq r22, r24, r21 /* Are we storing the value we loaded? */ + bbs r22, .Lcmpxchg32_nostore + sw r0, r24 + + /* The following instruction is the start of the second cache line. */ + /* Do slow mtspr here so the following "mf" waits less. */ + { + move sp, r27 + mtspr SPR_EX_CONTEXT_K_0, r28 + } + mf + + { + move r0, r21 + sw ATOMIC_LOCK_REG_NAME, zero + } + iret + + /* Duplicated code here in the case where we don't overlap "mf" */ +.Lcmpxchg32_nostore: + { + move r0, r21 + sw ATOMIC_LOCK_REG_NAME, zero + } + { + move sp, r27 + mtspr SPR_EX_CONTEXT_K_0, r28 + } + iret + + /* + * The locking code is the same for 32-bit cmpxchg/atomic_update, + * and for 64-bit cmpxchg. We provide it as a macro and put + * it into both versions. We can't share the code literally + * since it depends on having the right branch-back address. + */ + .macro cmpxchg_lock, bitwidth + + /* Lock; if we succeed, jump back up to the read-modify-write. */ +#ifdef CONFIG_SMP + tns r21, ATOMIC_LOCK_REG_NAME +#else + /* + * Non-SMP preserves all the lock infrastructure, to keep the + * code simpler for the interesting (SMP) case. However, we do + * one small optimization here and in atomic_asm.S, which is + * to fake out acquiring the actual lock in the atomic_lock table. + */ + movei r21, 0 +#endif + + /* Issue the slow SPR here while the tns result is in flight. */ + mfspr r28, SPR_EX_CONTEXT_K_0 + + { + addi r28, r28, 8 /* return to the instruction after the swint1 */ + bzt r21, .Ldo_cmpxchg\bitwidth + } + /* + * The preceding instruction is the last thing that must be + * hot in the icache before we do the "tns" above. + */ + +#ifdef CONFIG_SMP + /* + * We failed to acquire the tns lock on our first try. Now use + * bounded exponential backoff to retry, like __atomic_spinlock(). + */ + { + moveli r23, 2048 /* maximum backoff time in cycles */ + moveli r25, 32 /* starting backoff time in cycles */ + } +1: mfspr r26, CYCLE_LOW /* get start point for this backoff */ +2: mfspr r22, CYCLE_LOW /* test to see if we've backed off enough */ + sub r22, r22, r26 + slt r22, r22, r25 + bbst r22, 2b + { + shli r25, r25, 1 /* double the backoff; retry the tns */ + tns r21, ATOMIC_LOCK_REG_NAME + } + slt r26, r23, r25 /* is the proposed backoff too big? */ + { + mvnz r25, r26, r23 + bzt r21, .Ldo_cmpxchg\bitwidth + } + j 1b +#endif /* CONFIG_SMP */ + .endm + +.Lcmpxchg32_tns: + /* + * This is the last instruction on the second cache line. + * The nop here loads the second line, then we fall through + * to the tns to load the third line before we take the lock. + */ + nop + cmpxchg_lock 32 + + /* + * This code is invoked from sys_cmpxchg after most of the + * preconditions have been checked. We still need to check + * that r0 is 8-byte aligned, since if it's not we won't + * actually be atomic. However, ATOMIC_LOCK_REG has the atomic + * lock pointer and r27/r28 have the saved SP/PC. + * r23 is holding "r0 & 7" so we can test for alignment. + * The compare value is in r2/r3; the new value is in r4/r5. + * On return, we must put the old value in r0/r1. + */ + .align 64 +.Lcmpxchg64: + { + bzt r23, .Lcmpxchg64_tns + } + j .Lcmpxchg_badaddr + +.Ldo_cmpxchg64: + { + lw r21, r0 + addi r25, r0, 4 + } + { + lw r1, r25 + } + seq r26, r21, r2 + { + bz r26, .Lcmpxchg64_mismatch + seq r26, r1, r3 + } + { + bz r26, .Lcmpxchg64_mismatch + } + sw r0, r4 + sw r25, r5 + + /* + * The 32-bit path provides optimized "match" and "mismatch" + * iret paths, but we don't have enough bundles in this cache line + * to do that, so we just make even the "mismatch" path do an "mf". + */ +.Lcmpxchg64_mismatch: + { + move sp, r27 + mtspr SPR_EX_CONTEXT_K_0, r28 + } + mf + { + move r0, r21 + sw ATOMIC_LOCK_REG_NAME, zero + } + iret + +.Lcmpxchg64_tns: + cmpxchg_lock 64 + + + /* + * Reset sp and revector to sys_cmpxchg_badaddr(), which will + * just raise the appropriate signal and exit. Doing it this + * way means we don't have to duplicate the code in intvec.S's + * int_hand macro that locates the top of the stack. + */ +.Lcmpxchg_badaddr: + { + moveli TREG_SYSCALL_NR_NAME, __NR_cmpxchg_badaddr + move sp, r27 + } + j intvec_SWINT_1 + ENDPROC(sys_cmpxchg) + ENTRY(__sys_cmpxchg_end) + + +/* The single-step support may need to read all the registers. */ +int_unalign: + push_extra_callee_saves r0 + j do_trap + +/* Include .intrpt array of interrupt vectors */ + .section ".intrpt", "ax" + +#ifndef CONFIG_USE_PMC +#define handle_perf_interrupt bad_intr +#endif + +#ifndef CONFIG_HARDWALL +#define do_hardwall_trap bad_intr +#endif + + int_hand INT_ITLB_MISS, ITLB_MISS, \ + do_page_fault, handle_interrupt_no_single_step + int_hand INT_MEM_ERROR, MEM_ERROR, bad_intr + int_hand INT_ILL, ILL, do_trap, handle_ill + int_hand INT_GPV, GPV, do_trap + int_hand INT_SN_ACCESS, SN_ACCESS, do_trap + int_hand INT_IDN_ACCESS, IDN_ACCESS, do_trap + int_hand INT_UDN_ACCESS, UDN_ACCESS, do_trap + int_hand INT_IDN_REFILL, IDN_REFILL, bad_intr + int_hand INT_UDN_REFILL, UDN_REFILL, bad_intr + int_hand INT_IDN_COMPLETE, IDN_COMPLETE, bad_intr + int_hand INT_UDN_COMPLETE, UDN_COMPLETE, bad_intr + int_hand INT_SWINT_3, SWINT_3, do_trap + int_hand INT_SWINT_2, SWINT_2, do_trap + int_hand INT_SWINT_1, SWINT_1, SYSCALL, handle_syscall + int_hand INT_SWINT_0, SWINT_0, do_trap + int_hand INT_UNALIGN_DATA, UNALIGN_DATA, int_unalign + int_hand INT_DTLB_MISS, DTLB_MISS, do_page_fault + int_hand INT_DTLB_ACCESS, DTLB_ACCESS, do_page_fault + int_hand INT_DMATLB_MISS, DMATLB_MISS, do_page_fault + int_hand INT_DMATLB_ACCESS, DMATLB_ACCESS, do_page_fault + int_hand INT_SNITLB_MISS, SNITLB_MISS, do_page_fault + int_hand INT_SN_NOTIFY, SN_NOTIFY, bad_intr + int_hand INT_SN_FIREWALL, SN_FIREWALL, do_hardwall_trap + int_hand INT_IDN_FIREWALL, IDN_FIREWALL, bad_intr + int_hand INT_UDN_FIREWALL, UDN_FIREWALL, do_hardwall_trap + int_hand INT_TILE_TIMER, TILE_TIMER, do_timer_interrupt + int_hand INT_IDN_TIMER, IDN_TIMER, bad_intr + int_hand INT_UDN_TIMER, UDN_TIMER, bad_intr + int_hand INT_DMA_NOTIFY, DMA_NOTIFY, bad_intr + int_hand INT_IDN_CA, IDN_CA, bad_intr + int_hand INT_UDN_CA, UDN_CA, bad_intr + int_hand INT_IDN_AVAIL, IDN_AVAIL, bad_intr + int_hand INT_UDN_AVAIL, UDN_AVAIL, bad_intr + int_hand INT_PERF_COUNT, PERF_COUNT, \ + handle_perf_interrupt, handle_nmi + int_hand INT_INTCTRL_3, INTCTRL_3, bad_intr +#if CONFIG_KERNEL_PL == 2 + dc_dispatch INT_INTCTRL_2, INTCTRL_2 + int_hand INT_INTCTRL_1, INTCTRL_1, bad_intr +#else + int_hand INT_INTCTRL_2, INTCTRL_2, bad_intr + dc_dispatch INT_INTCTRL_1, INTCTRL_1 +#endif + int_hand INT_INTCTRL_0, INTCTRL_0, bad_intr + int_hand INT_MESSAGE_RCV_DWNCL, MESSAGE_RCV_DWNCL, \ + hv_message_intr + int_hand INT_DEV_INTR_DWNCL, DEV_INTR_DWNCL, \ + tile_dev_intr + int_hand INT_I_ASID, I_ASID, bad_intr + int_hand INT_D_ASID, D_ASID, bad_intr + int_hand INT_DMATLB_MISS_DWNCL, DMATLB_MISS_DWNCL, \ + do_page_fault + int_hand INT_SNITLB_MISS_DWNCL, SNITLB_MISS_DWNCL, \ + do_page_fault + int_hand INT_DMATLB_ACCESS_DWNCL, DMATLB_ACCESS_DWNCL, \ + do_page_fault + int_hand INT_SN_CPL, SN_CPL, bad_intr + int_hand INT_DOUBLE_FAULT, DOUBLE_FAULT, do_trap + int_hand INT_AUX_PERF_COUNT, AUX_PERF_COUNT, \ + handle_perf_interrupt, handle_nmi + + /* Synthetic interrupt delivered only by the simulator */ + int_hand INT_BREAKPOINT, BREAKPOINT, do_breakpoint |