From b059bdc39321696fe8f344acb7117d57fbd7b475 Mon Sep 17 00:00:00 2001 From: Russell King Date: Sat, 25 Jun 2011 15:44:20 +0100 Subject: [PATCH] ARM: entry: rejig register allocation in exception entry handlers This allows us to avoid moving registers twice to work around the clobbered registers when we add calls to trace_hardirqs_{on,off}. Ensure that all SVC handlers return with SPSR in r5 for consistency. Signed-off-by: Russell King --- arch/arm/kernel/entry-armv.S | 81 +++++++++++++++++++++++--------------------- 1 file changed, 43 insertions(+), 38 deletions(-) diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index fd42e66..582bb23 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -45,7 +45,7 @@ .endm .macro pabt_helper - mov r0, r2 @ pass address of aborted instruction. + mov r0, r4 @ pass address of aborted instruction. #ifdef MULTI_PABORT ldr ip, .LCprocfns mov lr, pc @@ -56,6 +56,8 @@ .endm .macro dabt_helper + mov r2, r4 + mov r3, r5 @ @ Call the processor-specific abort handler: @@ -157,26 +159,26 @@ ENDPROC(__und_invalid) SPFIX( subeq sp, sp, #4 ) stmia sp, {r1 - r12} - ldmia r0, {r1 - r3} - add r5, sp, #S_SP - 4 @ here for interlock avoidance - mov r4, #-1 @ "" "" "" "" - add r0, sp, #(S_FRAME_SIZE + \stack_hole - 4) - SPFIX( addeq r0, r0, #4 ) - str r1, [sp, #-4]! @ save the "real" r0 copied + ldmia r0, {r3 - r5} + add r7, sp, #S_SP - 4 @ here for interlock avoidance + mov r6, #-1 @ "" "" "" "" + add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4) + SPFIX( addeq r2, r2, #4 ) + str r3, [sp, #-4]! @ save the "real" r0 copied @ from the exception stack - mov r1, lr + mov r3, lr @ @ We are now ready to fill in the remaining blanks on the stack: @ - @ r0 - sp_svc - @ r1 - lr_svc - @ r2 - lr_, already fixed up for correct return/restart - @ r3 - spsr_ - @ r4 - orig_r0 (see pt_regs definition in ptrace.h) + @ r2 - sp_svc + @ r3 - lr_svc + @ r4 - lr_, already fixed up for correct return/restart + @ r5 - spsr_ + @ r6 - orig_r0 (see pt_regs definition in ptrace.h) @ - stmia r5, {r0 - r4} + stmia r7, {r2 - r6} .endm .align 5 @@ -187,7 +189,7 @@ __dabt_svc: @ get ready to re-enable interrupts if appropriate @ mrs r9, cpsr - tst r3, #PSR_I_BIT + tst r5, #PSR_I_BIT biceq r9, r9, #PSR_I_BIT dabt_helper @@ -208,8 +210,8 @@ __dabt_svc: @ @ restore SPSR and restart the instruction @ - ldr r2, [sp, #S_PSR] - svc_exit r2 @ return from exception + ldr r5, [sp, #S_PSR] + svc_exit r5 @ return from exception UNWIND(.fnend ) ENDPROC(__dabt_svc) @@ -232,13 +234,13 @@ __irq_svc: tst r0, #_TIF_NEED_RESCHED blne svc_preempt #endif - ldr r4, [sp, #S_PSR] @ irqs are already disabled + ldr r5, [sp, #S_PSR] #ifdef CONFIG_TRACE_IRQFLAGS @ The parent context IRQs must have been enabled to get here in @ the first place, so there's no point checking the PSR I bit. bl trace_hardirqs_on #endif - svc_exit r4 @ return from exception + svc_exit r5 @ return from exception UNWIND(.fnend ) ENDPROC(__irq_svc) @@ -273,15 +275,16 @@ __und_svc: @ r0 - instruction @ #ifndef CONFIG_THUMB2_KERNEL - ldr r0, [r2, #-4] + ldr r0, [r4, #-4] #else - ldrh r0, [r2, #-2] @ Thumb instruction at LR - 2 + ldrh r0, [r4, #-2] @ Thumb instruction at LR - 2 and r9, r0, #0xf800 cmp r9, #0xe800 @ 32-bit instruction if xx >= 0 - ldrhhs r9, [r2] @ bottom 16 bits + ldrhhs r9, [r4] @ bottom 16 bits orrhs r0, r9, r0, lsl #16 #endif adr r9, BSYM(1f) + mov r2, r4 bl call_fpe mov r0, sp @ struct pt_regs *regs @@ -295,8 +298,8 @@ __und_svc: @ @ restore SPSR and restart the instruction @ - ldr r2, [sp, #S_PSR] @ Get SVC cpsr - svc_exit r2 @ return from exception + ldr r5, [sp, #S_PSR] @ Get SVC cpsr + svc_exit r5 @ return from exception UNWIND(.fnend ) ENDPROC(__und_svc) @@ -308,7 +311,7 @@ __pabt_svc: @ re-enable interrupts if appropriate @ mrs r9, cpsr - tst r3, #PSR_I_BIT + tst r5, #PSR_I_BIT biceq r9, r9, #PSR_I_BIT pabt_helper @@ -325,8 +328,8 @@ __pabt_svc: @ @ restore SPSR and restart the instruction @ - ldr r2, [sp, #S_PSR] - svc_exit r2 @ return from exception + ldr r5, [sp, #S_PSR] + svc_exit r5 @ return from exception UNWIND(.fnend ) ENDPROC(__pabt_svc) @@ -357,23 +360,23 @@ ENDPROC(__pabt_svc) ARM( stmib sp, {r1 - r12} ) THUMB( stmia sp, {r0 - r12} ) - ldmia r0, {r1 - r3} + ldmia r0, {r3 - r5} add r0, sp, #S_PC @ here for interlock avoidance - mov r4, #-1 @ "" "" "" "" + mov r6, #-1 @ "" "" "" "" - str r1, [sp] @ save the "real" r0 copied + str r3, [sp] @ save the "real" r0 copied @ from the exception stack @ @ We are now ready to fill in the remaining blanks on the stack: @ - @ r2 - lr_, already fixed up for correct return/restart - @ r3 - spsr_ - @ r4 - orig_r0 (see pt_regs definition in ptrace.h) + @ r4 - lr_, already fixed up for correct return/restart + @ r5 - spsr_ + @ r6 - orig_r0 (see pt_regs definition in ptrace.h) @ @ Also, separately save sp_usr and lr_usr @ - stmia r0, {r2 - r4} + stmia r0, {r4 - r6} ARM( stmdb r0, {sp, lr}^ ) THUMB( store_user_sp_lr r0, r1, S_SP - S_PC ) @@ -397,7 +400,7 @@ ENDPROC(__pabt_svc) @ if it was interrupted in a critical region. Here we @ perform a quick test inline since it should be false @ 99.9999% of the time. The rest is done out of line. - cmp r2, #TASK_SIZE + cmp r4, #TASK_SIZE blhs kuser_cmpxchg_fixup #endif #endif @@ -441,6 +444,8 @@ ENDPROC(__irq_usr) .align 5 __und_usr: usr_entry + mov r2, r4 + mov r3, r5 @ @ fall through to the emulation code, which returns using r9 if @@ -894,13 +899,13 @@ __kuser_cmpxchg: @ 0xffff0fc0 .text kuser_cmpxchg_fixup: @ Called from kuser_cmpxchg_check macro. - @ r2 = address of interrupted insn (must be preserved). + @ r4 = address of interrupted insn (must be preserved). @ sp = saved regs. r7 and r8 are clobbered. @ 1b = first critical insn, 2b = last critical insn. - @ If r2 >= 1b and r2 <= 2b then saved pc_usr is set to 1b. + @ If r4 >= 1b and r4 <= 2b then saved pc_usr is set to 1b. mov r7, #0xffff0fff sub r7, r7, #(0xffff0fff - (0xffff0fc0 + (1b - __kuser_cmpxchg))) - subs r8, r2, r7 + subs r8, r4, r7 rsbcss r8, r8, #(2b - 1b) strcs r7, [sp, #S_PC] mov pc, lr -- 2.7.4