Initial import

1 files changed, 312 insertions, 0 deletions

diff --git a/arch/sparc/kernel/wuf.S b/arch/sparc/kernel/wuf.S
new file mode 100644
index 000000000..2c21cc596
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+++ b/arch/sparc/kernel/wuf.S
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+/*
+ * wuf.S: Window underflow trap handler for the Sparc.
+ *
+ * Copyright (C) 1995 David S. Miller
+ */
+
+#include <asm/contregs.h>
+#include <asm/page.h>
+#include <asm/ptrace.h>
+#include <asm/psr.h>
+#include <asm/smp.h>
+#include <asm/asi.h>
+#include <asm/winmacro.h>
+#include <asm/asmmacro.h>
+#include <asm/thread_info.h>
+
+/* Just like the overflow handler we define macros for registers
+ * with fixed meanings in this routine.
+ */
+#define t_psr       l0
+#define t_pc        l1
+#define t_npc       l2
+#define t_wim       l3
+/* Don't touch the above registers or else you die horribly... */
+
+/* Now macros for the available scratch registers in this routine. */
+#define twin_tmp1    l4
+#define twin_tmp2    l5
+
+#define curptr       g6
+
+	.text
+	.align	4
+
+	/* The trap entry point has executed the following:
+	 *
+	 * rd    %psr, %l0
+	 * rd    %wim, %l3
+	 * b     fill_window_entry
+	 * andcc %l0, PSR_PS, %g0
+	 */
+
+	/* Datum current_thread_info->uwinmask contains at all times a bitmask
+	 * where if any user windows are active, at least one bit will
+	 * be set in to mask.  If no user windows are active, the bitmask
+	 * will be all zeroes.
+	 */
+
+	/* To get an idea of what has just happened to cause this
+	 * trap take a look at this diagram:
+	 *
+	 *      1  2  3  4     <--  Window number
+	 *      ----------
+	 *      T  O  W  I     <--  Symbolic name
+	 *
+	 *      O == the window that execution was in when
+	 *           the restore was attempted
+	 *
+	 *      T == the trap itself has save'd us into this
+	 *           window
+	 *
+	 *      W == this window is the one which is now invalid
+	 *           and must be made valid plus loaded from the
+	 *           stack
+	 *
+	 *      I == this window will be the invalid one when we
+	 *           are done and return from trap if successful
+	 */
+
+	/* BEGINNING OF PATCH INSTRUCTIONS */
+
+	/* On 7-window Sparc the boot code patches fnwin_patch1
+	 * with the following instruction.
+	 */
+	.globl	fnwin_patch1_7win, fnwin_patch2_7win
+fnwin_patch1_7win:	srl	%t_wim, 6, %twin_tmp2
+fnwin_patch2_7win:	and	%twin_tmp1, 0x7f, %twin_tmp1
+	/* END OF PATCH INSTRUCTIONS */
+
+	.globl	fill_window_entry, fnwin_patch1, fnwin_patch2
+fill_window_entry:
+	/* LOCATION: Window 'T' */
+
+	/* Compute what the new %wim is going to be if we retrieve
+	 * the proper window off of the stack.
+	 */
+		sll	%t_wim, 1, %twin_tmp1
+fnwin_patch1:	srl	%t_wim, 7, %twin_tmp2
+		or	%twin_tmp1, %twin_tmp2, %twin_tmp1
+fnwin_patch2:	and	%twin_tmp1, 0xff, %twin_tmp1
+
+	wr	%twin_tmp1, 0x0, %wim	/* Make window 'I' invalid */
+
+	andcc	%t_psr, PSR_PS, %g0
+	be	fwin_from_user
+	 restore	%g0, %g0, %g0		/* Restore to window 'O' */
+
+	/* Trapped from kernel, we trust that the kernel does not
+	 * 'over restore' sorta speak and just grab the window
+	 * from the stack and return.  Easy enough.
+	 */
+fwin_from_kernel:
+	/* LOCATION: Window 'O' */
+
+	restore %g0, %g0, %g0
+
+	/* LOCATION: Window 'W' */
+
+	LOAD_WINDOW(sp)	                /* Load it up */
+
+	/* Spin the wheel... */
+	save	%g0, %g0, %g0
+	save	%g0, %g0, %g0
+	/* I'd like to buy a vowel please... */
+
+	/* LOCATION: Window 'T' */
+
+	/* Now preserve the condition codes in %psr, pause, and
+	 * return from trap.  This is the simplest case of all.
+	 */
+	wr	%t_psr, 0x0, %psr
+	WRITE_PAUSE
+
+	jmp	%t_pc
+	rett	%t_npc
+
+fwin_from_user:
+	/* LOCATION: Window 'O' */
+
+	restore	%g0, %g0, %g0		/* Restore to window 'W' */
+
+	/* LOCATION: Window 'W' */
+
+	/* Branch to the stack validation routine */
+	b	srmmu_fwin_stackchk
+	 andcc	%sp, 0x7, %g0
+
+#define STACK_OFFSET (THREAD_SIZE - TRACEREG_SZ - STACKFRAME_SZ)
+
+fwin_user_stack_is_bolixed:
+	/* LOCATION: Window 'W' */
+
+	/* Place a pt_regs frame on the kernel stack, save back
+	 * to the trap window and call c-code to deal with this.
+	 */
+	LOAD_CURRENT(l4, l5)
+
+	sethi	%hi(STACK_OFFSET), %l5
+	or	%l5, %lo(STACK_OFFSET), %l5
+	add	%l4, %l5, %l5
+
+	/* Store globals into pt_regs frame. */
+	STORE_PT_GLOBALS(l5)
+	STORE_PT_YREG(l5, g3)
+
+	/* Save current in a global while we change windows. */
+	mov	%l4, %curptr
+
+	save	%g0, %g0, %g0
+
+	/* LOCATION: Window 'O' */
+
+	rd	%psr, %g3		/* Read %psr in live user window */
+	mov	%fp, %g4		/* Save bogus frame pointer. */
+
+	save	%g0, %g0, %g0
+
+	/* LOCATION: Window 'T' */
+
+	sethi	%hi(STACK_OFFSET), %l5
+	or	%l5, %lo(STACK_OFFSET), %l5
+	add	%curptr, %l5, %sp
+
+	/* Build rest of pt_regs. */
+	STORE_PT_INS(sp)
+	STORE_PT_PRIV(sp, t_psr, t_pc, t_npc)
+
+	/* re-set trap time %wim value */
+	wr	%t_wim, 0x0, %wim
+
+	/* Fix users window mask and buffer save count. */
+	mov	0x1, %g5
+	sll	%g5, %g3, %g5
+	st	%g5, [%curptr + TI_UWINMASK]		! one live user window still
+	st	%g0, [%curptr + TI_W_SAVED]		! no windows in the buffer
+
+	wr	%t_psr, PSR_ET, %psr			! enable traps
+	nop
+	call	window_underflow_fault
+	 mov	%g4, %o0
+
+	b	ret_trap_entry
+	 clr	%l6
+
+fwin_user_stack_is_ok:
+	/* LOCATION: Window 'W' */
+
+	/* The users stack area is kosher and mapped, load the
+	 * window and fall through to the finish up routine.
+	 */
+	LOAD_WINDOW(sp)
+
+	/* Round and round she goes... */
+	save	%g0, %g0, %g0		/* Save to window 'O' */
+	save	%g0, %g0, %g0		/* Save to window 'T' */
+	/* Where she'll trap nobody knows... */
+
+	/* LOCATION: Window 'T' */
+
+fwin_user_finish_up:
+	/* LOCATION: Window 'T' */
+
+	wr	%t_psr, 0x0, %psr
+	WRITE_PAUSE	
+
+	jmp	%t_pc
+	rett	%t_npc
+
+	/* Here come the architecture specific checks for stack.
+	 * mappings.  Note that unlike the window overflow handler
+	 * we only need to check whether the user can read from
+	 * the appropriate addresses.  Also note that we are in
+	 * an invalid window which will be loaded, and this means
+	 * that until we actually load the window up we are free
+	 * to use any of the local registers contained within.
+	 *
+	 * On success these routine branch to fwin_user_stack_is_ok
+	 * if the area at %sp is user readable and the window still
+	 * needs to be loaded, else fwin_user_finish_up if the
+	 * routine has done the loading itself.  On failure (bogus
+	 * user stack) the routine shall branch to the label called
+	 * fwin_user_stack_is_bolixed.
+	 *
+	 * Contrary to the arch-specific window overflow stack
+	 * check routines in wof.S, these routines are free to use
+	 * any of the local registers they want to as this window
+	 * does not belong to anyone at this point, however the
+	 * outs and ins are still verboten as they are part of
+	 * 'someone elses' window possibly.
+	 */
+
+	.globl	srmmu_fwin_stackchk
+srmmu_fwin_stackchk:
+	/* LOCATION: Window 'W' */
+
+	/* Caller did 'andcc %sp, 0x7, %g0' */
+	bne	fwin_user_stack_is_bolixed
+	 sethi   %hi(PAGE_OFFSET), %l5
+
+	/* Check if the users stack is in kernel vma, then our
+	 * trial and error technique below would succeed for
+	 * the 'wrong' reason.
+	 */
+	mov	AC_M_SFSR, %l4
+	cmp	%l5, %sp
+	bleu	fwin_user_stack_is_bolixed
+LEON_PI( lda	[%l4] ASI_LEON_MMUREGS, %g0)	! clear fault status
+SUN_PI_( lda	[%l4] ASI_M_MMUREGS, %g0)	! clear fault status
+
+	/* The technique is, turn off faults on this processor,
+	 * just let the load rip, then check the sfsr to see if
+	 * a fault did occur.  Then we turn on fault traps again
+	 * and branch conditionally based upon what happened.
+	 */
+LEON_PI(lda	[%g0] ASI_LEON_MMUREGS, %l5)	! read mmu-ctrl reg
+SUN_PI_(lda	[%g0] ASI_M_MMUREGS, %l5)	! read mmu-ctrl reg
+	or	%l5, 0x2, %l5			! turn on no-fault bit
+LEON_PI(sta	%l5, [%g0] ASI_LEON_MMUREGS)	! store it
+SUN_PI_(sta	%l5, [%g0] ASI_M_MMUREGS)	! store it
+
+	/* Cross fingers and go for it. */
+	LOAD_WINDOW(sp)
+
+	/* A penny 'saved'... */
+	save	%g0, %g0, %g0
+	save	%g0, %g0, %g0
+	/* Is a BADTRAP earned... */
+
+	/* LOCATION: Window 'T' */
+
+LEON_PI(lda	[%g0] ASI_LEON_MMUREGS, %twin_tmp1)	! load mmu-ctrl again
+SUN_PI_(lda	[%g0] ASI_M_MMUREGS, %twin_tmp1)	! load mmu-ctrl again
+	andn	%twin_tmp1, 0x2, %twin_tmp1		! clear no-fault bit
+LEON_PI(sta	%twin_tmp1, [%g0] ASI_LEON_MMUREGS)	! store it
+SUN_PI_(sta	%twin_tmp1, [%g0] ASI_M_MMUREGS)	! store it
+
+	mov	AC_M_SFAR, %twin_tmp2
+LEON_PI(lda	[%twin_tmp2] ASI_LEON_MMUREGS, %g0)	! read fault address
+SUN_PI_(lda	[%twin_tmp2] ASI_M_MMUREGS, %g0)	! read fault address
+
+	mov	AC_M_SFSR, %twin_tmp2
+LEON_PI(lda	[%twin_tmp2] ASI_LEON_MMUREGS, %twin_tmp2) ! read fault status
+SUN_PI_(lda	[%twin_tmp2] ASI_M_MMUREGS, %twin_tmp2)	   ! read fault status
+	andcc	%twin_tmp2, 0x2, %g0			   ! did fault occur?
+
+	bne	1f					   ! yep, cleanup
+	 nop
+
+	wr	%t_psr, 0x0, %psr
+	nop
+	b	fwin_user_finish_up + 0x4
+	 nop
+
+	/* Did I ever tell you about my window lobotomy?
+	 * anyways... fwin_user_stack_is_bolixed expects
+	 * to be in window 'W' so make it happy or else
+	 * we watchdog badly.
+	 */
+1:
+	restore	%g0, %g0, %g0
+	b	fwin_user_stack_is_bolixed	! oh well
+	 restore	%g0, %g0, %g0