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Diffstat (limited to 'arch/ia64/kernel/gate.S')
| -rw-r--r-- | arch/ia64/kernel/gate.S | 386 |
1 files changed, 386 insertions, 0 deletions
diff --git a/arch/ia64/kernel/gate.S b/arch/ia64/kernel/gate.S new file mode 100644 index 000000000..b5f8bdd86 --- /dev/null +++ b/arch/ia64/kernel/gate.S @@ -0,0 +1,386 @@ +/* + * This file contains the code that gets mapped at the upper end of each task's text + * region. For now, it contains the signal trampoline code only. + * + * Copyright (C) 1999-2003 Hewlett-Packard Co + * David Mosberger-Tang <davidm@hpl.hp.com> + */ + + +#include <asm/asmmacro.h> +#include <asm/errno.h> +#include <asm/asm-offsets.h> +#include <asm/sigcontext.h> +#include <asm/unistd.h> +#include <asm/kregs.h> +#include <asm/page.h> +#include "paravirt_inst.h" + +/* + * We can't easily refer to symbols inside the kernel. To avoid full runtime relocation, + * complications with the linker (which likes to create PLT stubs for branches + * to targets outside the shared object) and to avoid multi-phase kernel builds, we + * simply create minimalistic "patch lists" in special ELF sections. + */ + .section ".data..patch.fsyscall_table", "a" + .previous +#define LOAD_FSYSCALL_TABLE(reg) \ +[1:] movl reg=0; \ + .xdata4 ".data..patch.fsyscall_table", 1b-. + + .section ".data..patch.brl_fsys_bubble_down", "a" + .previous +#define BRL_COND_FSYS_BUBBLE_DOWN(pr) \ +[1:](pr)brl.cond.sptk 0; \ + ;; \ + .xdata4 ".data..patch.brl_fsys_bubble_down", 1b-. + +GLOBAL_ENTRY(__kernel_syscall_via_break) + .prologue + .altrp b6 + .body + /* + * Note: for (fast) syscall restart to work, the break instruction must be + * the first one in the bundle addressed by syscall_via_break. + */ +{ .mib + break 0x100000 + nop.i 0 + br.ret.sptk.many b6 +} +END(__kernel_syscall_via_break) + +# define ARG0_OFF (16 + IA64_SIGFRAME_ARG0_OFFSET) +# define ARG1_OFF (16 + IA64_SIGFRAME_ARG1_OFFSET) +# define ARG2_OFF (16 + IA64_SIGFRAME_ARG2_OFFSET) +# define SIGHANDLER_OFF (16 + IA64_SIGFRAME_HANDLER_OFFSET) +# define SIGCONTEXT_OFF (16 + IA64_SIGFRAME_SIGCONTEXT_OFFSET) + +# define FLAGS_OFF IA64_SIGCONTEXT_FLAGS_OFFSET +# define CFM_OFF IA64_SIGCONTEXT_CFM_OFFSET +# define FR6_OFF IA64_SIGCONTEXT_FR6_OFFSET +# define BSP_OFF IA64_SIGCONTEXT_AR_BSP_OFFSET +# define RNAT_OFF IA64_SIGCONTEXT_AR_RNAT_OFFSET +# define UNAT_OFF IA64_SIGCONTEXT_AR_UNAT_OFFSET +# define FPSR_OFF IA64_SIGCONTEXT_AR_FPSR_OFFSET +# define PR_OFF IA64_SIGCONTEXT_PR_OFFSET +# define RP_OFF IA64_SIGCONTEXT_IP_OFFSET +# define SP_OFF IA64_SIGCONTEXT_R12_OFFSET +# define RBS_BASE_OFF IA64_SIGCONTEXT_RBS_BASE_OFFSET +# define LOADRS_OFF IA64_SIGCONTEXT_LOADRS_OFFSET +# define base0 r2 +# define base1 r3 + /* + * When we get here, the memory stack looks like this: + * + * +===============================+ + * | | + * // struct sigframe // + * | | + * +-------------------------------+ <-- sp+16 + * | 16 byte of scratch | + * | space | + * +-------------------------------+ <-- sp + * + * The register stack looks _exactly_ the way it looked at the time the signal + * occurred. In other words, we're treading on a potential mine-field: each + * incoming general register may be a NaT value (including sp, in which case the + * process ends up dying with a SIGSEGV). + * + * The first thing need to do is a cover to get the registers onto the backing + * store. Once that is done, we invoke the signal handler which may modify some + * of the machine state. After returning from the signal handler, we return + * control to the previous context by executing a sigreturn system call. A signal + * handler may call the rt_sigreturn() function to directly return to a given + * sigcontext. However, the user-level sigreturn() needs to do much more than + * calling the rt_sigreturn() system call as it needs to unwind the stack to + * restore preserved registers that may have been saved on the signal handler's + * call stack. + */ + +#define SIGTRAMP_SAVES \ + .unwabi 3, 's'; /* mark this as a sigtramp handler (saves scratch regs) */ \ + .unwabi @svr4, 's'; /* backwards compatibility with old unwinders (remove in v2.7) */ \ + .savesp ar.unat, UNAT_OFF+SIGCONTEXT_OFF; \ + .savesp ar.fpsr, FPSR_OFF+SIGCONTEXT_OFF; \ + .savesp pr, PR_OFF+SIGCONTEXT_OFF; \ + .savesp rp, RP_OFF+SIGCONTEXT_OFF; \ + .savesp ar.pfs, CFM_OFF+SIGCONTEXT_OFF; \ + .vframesp SP_OFF+SIGCONTEXT_OFF + +GLOBAL_ENTRY(__kernel_sigtramp) + // describe the state that is active when we get here: + .prologue + SIGTRAMP_SAVES + .body + + .label_state 1 + + adds base0=SIGHANDLER_OFF,sp + adds base1=RBS_BASE_OFF+SIGCONTEXT_OFF,sp + br.call.sptk.many rp=1f +1: + ld8 r17=[base0],(ARG0_OFF-SIGHANDLER_OFF) // get pointer to signal handler's plabel + ld8 r15=[base1] // get address of new RBS base (or NULL) + cover // push args in interrupted frame onto backing store + ;; + cmp.ne p1,p0=r15,r0 // do we need to switch rbs? (note: pr is saved by kernel) + mov.m r9=ar.bsp // fetch ar.bsp + .spillsp.p p1, ar.rnat, RNAT_OFF+SIGCONTEXT_OFF +(p1) br.cond.spnt setup_rbs // yup -> (clobbers p8, r14-r16, and r18-r20) +back_from_setup_rbs: + alloc r8=ar.pfs,0,0,3,0 + ld8 out0=[base0],16 // load arg0 (signum) + adds base1=(ARG1_OFF-(RBS_BASE_OFF+SIGCONTEXT_OFF)),base1 + ;; + ld8 out1=[base1] // load arg1 (siginfop) + ld8 r10=[r17],8 // get signal handler entry point + ;; + ld8 out2=[base0] // load arg2 (sigcontextp) + ld8 gp=[r17] // get signal handler's global pointer + adds base0=(BSP_OFF+SIGCONTEXT_OFF),sp + ;; + .spillsp ar.bsp, BSP_OFF+SIGCONTEXT_OFF + st8 [base0]=r9 // save sc_ar_bsp + adds base0=(FR6_OFF+SIGCONTEXT_OFF),sp + adds base1=(FR6_OFF+16+SIGCONTEXT_OFF),sp + ;; + stf.spill [base0]=f6,32 + stf.spill [base1]=f7,32 + ;; + stf.spill [base0]=f8,32 + stf.spill [base1]=f9,32 + mov b6=r10 + ;; + stf.spill [base0]=f10,32 + stf.spill [base1]=f11,32 + ;; + stf.spill [base0]=f12,32 + stf.spill [base1]=f13,32 + ;; + stf.spill [base0]=f14,32 + stf.spill [base1]=f15,32 + br.call.sptk.many rp=b6 // call the signal handler +.ret0: adds base0=(BSP_OFF+SIGCONTEXT_OFF),sp + ;; + ld8 r15=[base0] // fetch sc_ar_bsp + mov r14=ar.bsp + ;; + cmp.ne p1,p0=r14,r15 // do we need to restore the rbs? +(p1) br.cond.spnt restore_rbs // yup -> (clobbers r14-r18, f6 & f7) + ;; +back_from_restore_rbs: + adds base0=(FR6_OFF+SIGCONTEXT_OFF),sp + adds base1=(FR6_OFF+16+SIGCONTEXT_OFF),sp + ;; + ldf.fill f6=[base0],32 + ldf.fill f7=[base1],32 + ;; + ldf.fill f8=[base0],32 + ldf.fill f9=[base1],32 + ;; + ldf.fill f10=[base0],32 + ldf.fill f11=[base1],32 + ;; + ldf.fill f12=[base0],32 + ldf.fill f13=[base1],32 + ;; + ldf.fill f14=[base0],32 + ldf.fill f15=[base1],32 + mov r15=__NR_rt_sigreturn + .restore sp // pop .prologue + break __BREAK_SYSCALL + + .prologue + SIGTRAMP_SAVES +setup_rbs: + mov ar.rsc=0 // put RSE into enforced lazy mode + ;; + .save ar.rnat, r19 + mov r19=ar.rnat // save RNaT before switching backing store area + adds r14=(RNAT_OFF+SIGCONTEXT_OFF),sp + + mov r18=ar.bspstore + mov ar.bspstore=r15 // switch over to new register backing store area + ;; + + .spillsp ar.rnat, RNAT_OFF+SIGCONTEXT_OFF + st8 [r14]=r19 // save sc_ar_rnat + .body + mov.m r16=ar.bsp // sc_loadrs <- (new bsp - new bspstore) << 16 + adds r14=(LOADRS_OFF+SIGCONTEXT_OFF),sp + ;; + invala + sub r15=r16,r15 + extr.u r20=r18,3,6 + ;; + mov ar.rsc=0xf // set RSE into eager mode, pl 3 + cmp.eq p8,p0=63,r20 + shl r15=r15,16 + ;; + st8 [r14]=r15 // save sc_loadrs +(p8) st8 [r18]=r19 // if bspstore points at RNaT slot, store RNaT there now + .restore sp // pop .prologue + br.cond.sptk back_from_setup_rbs + + .prologue + SIGTRAMP_SAVES + .spillsp ar.rnat, RNAT_OFF+SIGCONTEXT_OFF + .body +restore_rbs: + // On input: + // r14 = bsp1 (bsp at the time of return from signal handler) + // r15 = bsp0 (bsp at the time the signal occurred) + // + // Here, we need to calculate bspstore0, the value that ar.bspstore needs + // to be set to, based on bsp0 and the size of the dirty partition on + // the alternate stack (sc_loadrs >> 16). This can be done with the + // following algorithm: + // + // bspstore0 = rse_skip_regs(bsp0, -rse_num_regs(bsp1 - (loadrs >> 19), bsp1)); + // + // This is what the code below does. + // + alloc r2=ar.pfs,0,0,0,0 // alloc null frame + adds r16=(LOADRS_OFF+SIGCONTEXT_OFF),sp + adds r18=(RNAT_OFF+SIGCONTEXT_OFF),sp + ;; + ld8 r17=[r16] + ld8 r16=[r18] // get new rnat + extr.u r18=r15,3,6 // r18 <- rse_slot_num(bsp0) + ;; + mov ar.rsc=r17 // put RSE into enforced lazy mode + shr.u r17=r17,16 + ;; + sub r14=r14,r17 // r14 (bspstore1) <- bsp1 - (sc_loadrs >> 16) + shr.u r17=r17,3 // r17 <- (sc_loadrs >> 19) + ;; + loadrs // restore dirty partition + extr.u r14=r14,3,6 // r14 <- rse_slot_num(bspstore1) + ;; + add r14=r14,r17 // r14 <- rse_slot_num(bspstore1) + (sc_loadrs >> 19) + ;; + shr.u r14=r14,6 // r14 <- (rse_slot_num(bspstore1) + (sc_loadrs >> 19))/0x40 + ;; + sub r14=r14,r17 // r14 <- -rse_num_regs(bspstore1, bsp1) + movl r17=0x8208208208208209 + ;; + add r18=r18,r14 // r18 (delta) <- rse_slot_num(bsp0) - rse_num_regs(bspstore1,bsp1) + setf.sig f7=r17 + cmp.lt p7,p0=r14,r0 // p7 <- (r14 < 0)? + ;; +(p7) adds r18=-62,r18 // delta -= 62 + ;; + setf.sig f6=r18 + ;; + xmpy.h f6=f6,f7 + ;; + getf.sig r17=f6 + ;; + add r17=r17,r18 + shr r18=r18,63 + ;; + shr r17=r17,5 + ;; + sub r17=r17,r18 // r17 = delta/63 + ;; + add r17=r14,r17 // r17 <- delta/63 - rse_num_regs(bspstore1, bsp1) + ;; + shladd r15=r17,3,r15 // r15 <- bsp0 + 8*(delta/63 - rse_num_regs(bspstore1, bsp1)) + ;; + mov ar.bspstore=r15 // switch back to old register backing store area + ;; + mov ar.rnat=r16 // restore RNaT + mov ar.rsc=0xf // (will be restored later on from sc_ar_rsc) + // invala not necessary as that will happen when returning to user-mode + br.cond.sptk back_from_restore_rbs +END(__kernel_sigtramp) + +/* + * On entry: + * r11 = saved ar.pfs + * r15 = system call # + * b0 = saved return address + * b6 = return address + * On exit: + * r11 = saved ar.pfs + * r15 = system call # + * b0 = saved return address + * all other "scratch" registers: undefined + * all "preserved" registers: same as on entry + */ + +GLOBAL_ENTRY(__kernel_syscall_via_epc) + .prologue + .altrp b6 + .body +{ + /* + * Note: the kernel cannot assume that the first two instructions in this + * bundle get executed. The remaining code must be safe even if + * they do not get executed. + */ + adds r17=-1024,r15 // A + mov r10=0 // A default to successful syscall execution + epc // B causes split-issue +} + ;; + RSM_PSR_BE_I(r20, r22) // M2 (5 cyc to srlz.d) + LOAD_FSYSCALL_TABLE(r14) // X + ;; + mov r16=IA64_KR(CURRENT) // M2 (12 cyc) + shladd r18=r17,3,r14 // A + mov r19=NR_syscalls-1 // A + ;; + lfetch [r18] // M0|1 + MOV_FROM_PSR(p0, r29, r8) // M2 (12 cyc) + // If r17 is a NaT, p6 will be zero + cmp.geu p6,p7=r19,r17 // A (sysnr > 0 && sysnr < 1024+NR_syscalls)? + ;; + mov r21=ar.fpsr // M2 (12 cyc) + tnat.nz p10,p9=r15 // I0 + mov.i r26=ar.pfs // I0 (would stall anyhow due to srlz.d...) + ;; + srlz.d // M0 (forces split-issue) ensure PSR.BE==0 +(p6) ld8 r18=[r18] // M0|1 + nop.i 0 + ;; + nop.m 0 +(p6) tbit.z.unc p8,p0=r18,0 // I0 (dual-issues with "mov b7=r18"!) + nop.i 0 + ;; + SSM_PSR_I(p8, p14, r25) +(p6) mov b7=r18 // I0 +(p8) br.dptk.many b7 // B + + mov r27=ar.rsc // M2 (12 cyc) +/* + * brl.cond doesn't work as intended because the linker would convert this branch + * into a branch to a PLT. Perhaps there will be a way to avoid this with some + * future version of the linker. In the meantime, we just use an indirect branch + * instead. + */ +#ifdef CONFIG_ITANIUM +(p6) add r14=-8,r14 // r14 <- addr of fsys_bubble_down entry + ;; +(p6) ld8 r14=[r14] // r14 <- fsys_bubble_down + ;; +(p6) mov b7=r14 +(p6) br.sptk.many b7 +#else + BRL_COND_FSYS_BUBBLE_DOWN(p6) +#endif + SSM_PSR_I(p0, p14, r10) + mov r10=-1 +(p10) mov r8=EINVAL +(p9) mov r8=ENOSYS + FSYS_RETURN + +#ifdef CONFIG_PARAVIRT + /* + * padd to make the size of this symbol constant + * independent of paravirtualization. + */ + .align PAGE_SIZE / 8 +#endif +END(__kernel_syscall_via_epc) |