From b96bae3ae2cb6337c0a1ad160f4cbb0666e5e38b Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Fri, 12 Mar 2021 12:50:34 +0000 Subject: [PATCH] powerpc/32: Replace ASM exception exit by C exception exit from ppc64 This patch replaces the PPC32 ASM exception exit by C exception exit. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/48f8bae91da899d8e73fc0d75c9af66cc97b4d5b.1615552867.git.christophe.leroy@csgroup.eu --- arch/powerpc/kernel/entry_32.S | 462 +++++++++----------------------- arch/powerpc/kernel/interrupt.c | 6 +- 2 files changed, 136 insertions(+), 332 deletions(-) diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index 7084289994b3..79311d0bd09b 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -336,7 +336,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_SPE) fast_exception_return: #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) andi. r10,r9,MSR_RI /* check for recoverable interrupt */ - beq 1f /* if not, we've got problems */ + beq 3f /* if not, we've got problems */ #endif 2: REST_4GPRS(3, r11) @@ -363,30 +363,6 @@ fast_exception_return: #endif _ASM_NOKPROBE_SYMBOL(fast_exception_return) -#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) -/* check if the exception happened in a restartable section */ -1: lis r3,exc_exit_restart_end@ha - addi r3,r3,exc_exit_restart_end@l - cmplw r12,r3 - bge 3f - lis r4,exc_exit_restart@ha - addi r4,r4,exc_exit_restart@l - cmplw r12,r4 - blt 3f - lis r3,fee_restarts@ha - tophys(r3,r3) - lwz r5,fee_restarts@l(r3) - addi r5,r5,1 - stw r5,fee_restarts@l(r3) - mr r12,r4 /* restart at exc_exit_restart */ - b 2b - - .section .bss - .align 2 -fee_restarts: - .space 4 - .previous - /* aargh, a nonrecoverable interrupt, panic */ /* aargh, we don't know which trap this is */ 3: @@ -395,8 +371,7 @@ fee_restarts: addi r3,r1,STACK_FRAME_OVERHEAD bl transfer_to_handler_full bl unrecoverable_exception - b ret_from_except -#endif + trap /* should not get here */ .globl ret_from_except_full ret_from_except_full: @@ -405,213 +380,145 @@ ret_from_except_full: .globl ret_from_except ret_from_except: - /* Hard-disable interrupts so that current_thread_info()->flags - * can't change between when we test it and when we return - * from the interrupt. */ - /* Note: We don't bother telling lockdep about it */ - LOAD_REG_IMMEDIATE(r10,MSR_KERNEL) - mtmsr r10 /* disable interrupts */ +_ASM_NOKPROBE_SYMBOL(ret_from_except) - lwz r3,_MSR(r1) /* Returning to user mode? */ - andi. r0,r3,MSR_PR - beq resume_kernel + .globl interrupt_return +interrupt_return: + lwz r4,_MSR(r1) + addi r3,r1,STACK_FRAME_OVERHEAD + andi. r0,r4,MSR_PR + beq .Lkernel_interrupt_return + bl interrupt_exit_user_prepare + cmpwi r3,0 + bne- .Lrestore_nvgprs -user_exc_return: /* r10 contains MSR_KERNEL here */ - /* Check current_thread_info()->flags */ - lwz r9,TI_FLAGS(r2) - andi. r0,r9,_TIF_USER_WORK_MASK - bne do_work - -restore_user: -#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE) - /* Check whether this process has its own DBCR0 value. The internal - debug mode bit tells us that dbcr0 should be loaded. */ - lwz r0,THREAD+THREAD_DBCR0(r2) - andis. r10,r0,DBCR0_IDM@h - bnel- load_dbcr0 -#endif - ACCOUNT_CPU_USER_EXIT(r2, r10, r11) +.Lfast_user_interrupt_return: #ifdef CONFIG_PPC_BOOK3S_32 kuep_unlock r10, r11 #endif - - b restore - -/* N.B. the only way to get here is from the beq following ret_from_except. */ -resume_kernel: - /* check current_thread_info, _TIF_EMULATE_STACK_STORE */ - lwz r8,TI_FLAGS(r2) - andis. r0,r8,_TIF_EMULATE_STACK_STORE@h - beq+ 1f - - addi r8,r1,INT_FRAME_SIZE /* Get the kprobed function entry */ - - lwz r3,GPR1(r1) - subi r3,r3,INT_FRAME_SIZE /* dst: Allocate a trampoline exception frame */ - mr r4,r1 /* src: current exception frame */ - mr r1,r3 /* Reroute the trampoline frame to r1 */ - - /* Copy from the original to the trampoline. */ - li r5,INT_FRAME_SIZE/4 /* size: INT_FRAME_SIZE */ - li r6,0 /* start offset: 0 */ - mtctr r5 -2: lwzx r0,r6,r4 - stwx r0,r6,r3 - addi r6,r6,4 - bdnz 2b - - /* Do real store operation to complete stwu */ - lwz r5,GPR1(r1) - stw r8,0(r5) - - /* Clear _TIF_EMULATE_STACK_STORE flag */ - lis r11,_TIF_EMULATE_STACK_STORE@h - addi r5,r2,TI_FLAGS -0: lwarx r8,0,r5 - andc r8,r8,r11 - stwcx. r8,0,r5 - bne- 0b -1: - -#ifdef CONFIG_PREEMPTION - /* check current_thread_info->preempt_count */ - lwz r0,TI_PREEMPT(r2) - cmpwi 0,r0,0 /* if non-zero, just restore regs and return */ - bne restore_kuap - andi. r8,r8,_TIF_NEED_RESCHED - beq+ restore_kuap - lwz r3,_MSR(r1) - andi. r0,r3,MSR_EE /* interrupts off? */ - beq restore_kuap /* don't schedule if so */ -#ifdef CONFIG_TRACE_IRQFLAGS - /* Lockdep thinks irqs are enabled, we need to call - * preempt_schedule_irq with IRQs off, so we inform lockdep - * now that we -did- turn them off already - */ - bl trace_hardirqs_off -#endif - bl preempt_schedule_irq -#ifdef CONFIG_TRACE_IRQFLAGS - /* And now, to properly rebalance the above, we tell lockdep they - * are being turned back on, which will happen when we return - */ - bl trace_hardirqs_on -#endif -#endif /* CONFIG_PREEMPTION */ -restore_kuap: - kuap_restore r1, r2, r9, r10, r0 - - /* interrupts are hard-disabled at this point */ -restore: -#if defined(CONFIG_44x) && !defined(CONFIG_PPC_47x) - lis r4,icache_44x_need_flush@ha - lwz r5,icache_44x_need_flush@l(r4) - cmplwi cr0,r5,0 - beq+ 1f - li r6,0 - iccci r0,r0 - stw r6,icache_44x_need_flush@l(r4) -1: -#endif /* CONFIG_44x */ - - lwz r9,_MSR(r1) -#ifdef CONFIG_TRACE_IRQFLAGS - /* Lockdep doesn't know about the fact that IRQs are temporarily turned - * off in this assembly code while peeking at TI_FLAGS() and such. However - * we need to inform it if the exception turned interrupts off, and we - * are about to trun them back on. - */ - andi. r10,r9,MSR_EE - beq 1f - stwu r1,-32(r1) - mflr r0 - stw r0,4(r1) - bl trace_hardirqs_on - addi r1, r1, 32 - lwz r9,_MSR(r1) -1: -#endif /* CONFIG_TRACE_IRQFLAGS */ - - lwz r0,GPR0(r1) - lwz r2,GPR2(r1) - REST_4GPRS(3, r1) - REST_2GPRS(7, r1) - - lwz r10,_XER(r1) - lwz r11,_CTR(r1) - mtspr SPRN_XER,r10 - mtctr r11 - -BEGIN_FTR_SECTION - lwarx r11,0,r1 -END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX) - stwcx. r0,0,r1 /* to clear the reservation */ - -#if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) - andi. r10,r9,MSR_RI /* check if this exception occurred */ - beql nonrecoverable /* at a bad place (MSR:RI = 0) */ - - lwz r10,_CCR(r1) - lwz r11,_LINK(r1) - mtcrf 0xFF,r10 - mtlr r11 - - /* Clear the exception_marker on the stack to avoid confusing stacktrace */ - li r10, 0 - stw r10, 8(r1) - /* - * Once we put values in SRR0 and SRR1, we are in a state - * where exceptions are not recoverable, since taking an - * exception will trash SRR0 and SRR1. Therefore we clear the - * MSR:RI bit to indicate this. If we do take an exception, - * we can't return to the point of the exception but we - * can restart the exception exit path at the label - * exc_exit_restart below. -- paulus - */ - LOAD_REG_IMMEDIATE(r10,MSR_KERNEL & ~MSR_RI) - mtmsr r10 /* clear the RI bit */ - .globl exc_exit_restart -exc_exit_restart: - lwz r12,_NIP(r1) - mtspr SPRN_SRR0,r12 - mtspr SPRN_SRR1,r9 - REST_4GPRS(9, r1) - lwz r1,GPR1(r1) - .globl exc_exit_restart_end -exc_exit_restart_end: - rfi -_ASM_NOKPROBE_SYMBOL(exc_exit_restart) -_ASM_NOKPROBE_SYMBOL(exc_exit_restart_end) - -#else /* !(CONFIG_4xx || CONFIG_BOOKE) */ - /* - * This is a bit different on 4xx/Book-E because it doesn't have - * the RI bit in the MSR. - * The TLB miss handler checks if we have interrupted - * the exception exit path and restarts it if so - * (well maybe one day it will... :). - */ - lwz r11,_LINK(r1) - mtlr r11 - lwz r10,_CCR(r1) - mtcrf 0xff,r10 - /* Clear the exception_marker on the stack to avoid confusing stacktrace */ - li r10, 0 - stw r10, 8(r1) - REST_2GPRS(9, r1) - .globl exc_exit_restart -exc_exit_restart: + kuap_check r2, r4 lwz r11,_NIP(r1) lwz r12,_MSR(r1) mtspr SPRN_SRR0,r11 mtspr SPRN_SRR1,r12 + +BEGIN_FTR_SECTION + stwcx. r0,0,r1 /* to clear the reservation */ +FTR_SECTION_ELSE + lwarx r0,0,r1 +ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) + + lwz r3,_CCR(r1) + lwz r4,_LINK(r1) + lwz r5,_CTR(r1) + lwz r6,_XER(r1) + li r0,0 + + /* + * Leaving a stale exception_marker on the stack can confuse + * the reliable stack unwinder later on. Clear it. + */ + stw r0,8(r1) + REST_4GPRS(7, r1) REST_2GPRS(11, r1) - lwz r1,GPR1(r1) - .globl exc_exit_restart_end -exc_exit_restart_end: + + mtcr r3 + mtlr r4 + mtctr r5 + mtspr SPRN_XER,r6 + + REST_4GPRS(2, r1) + REST_GPR(6, r1) + REST_GPR(0, r1) + REST_GPR(1, r1) rfi - b . /* prevent prefetch past rfi */ -_ASM_NOKPROBE_SYMBOL(exc_exit_restart) +#ifdef CONFIG_40x + b . /* Prevent prefetch past rfi */ +#endif + +.Lrestore_nvgprs: + REST_NVGPRS(r1) + b .Lfast_user_interrupt_return + +.Lkernel_interrupt_return: + bl interrupt_exit_kernel_prepare + +.Lfast_kernel_interrupt_return: + cmpwi cr1,r3,0 + kuap_restore r1, r2, r3, r4, r5 + lwz r11,_NIP(r1) + lwz r12,_MSR(r1) + mtspr SPRN_SRR0,r11 + mtspr SPRN_SRR1,r12 + +BEGIN_FTR_SECTION + stwcx. r0,0,r1 /* to clear the reservation */ +FTR_SECTION_ELSE + lwarx r0,0,r1 +ALT_FTR_SECTION_END_IFCLR(CPU_FTR_STCX_CHECKS_ADDRESS) + + lwz r3,_LINK(r1) + lwz r4,_CTR(r1) + lwz r5,_XER(r1) + lwz r6,_CCR(r1) + li r0,0 + + REST_4GPRS(7, r1) + REST_2GPRS(11, r1) + + mtlr r3 + mtctr r4 + mtspr SPRN_XER,r5 + + /* + * Leaving a stale exception_marker on the stack can confuse + * the reliable stack unwinder later on. Clear it. + */ + stw r0,8(r1) + + REST_4GPRS(2, r1) + + bne- cr1,1f /* emulate stack store */ + mtcr r6 + REST_GPR(6, r1) + REST_GPR(0, r1) + REST_GPR(1, r1) + rfi +#ifdef CONFIG_40x + b . /* Prevent prefetch past rfi */ +#endif + +1: /* + * Emulate stack store with update. New r1 value was already calculated + * and updated in our interrupt regs by emulate_loadstore, but we can't + * store the previous value of r1 to the stack before re-loading our + * registers from it, otherwise they could be clobbered. Use + * SPRG Scratch0 as temporary storage to hold the store + * data, as interrupts are disabled here so it won't be clobbered. + */ + mtcr r6 +#ifdef CONFIG_BOOKE + mtspr SPRN_SPRG_WSCRATCH0, r9 +#else + mtspr SPRN_SPRG_SCRATCH0, r9 +#endif + addi r9,r1,INT_FRAME_SIZE /* get original r1 */ + REST_GPR(6, r1) + REST_GPR(0, r1) + REST_GPR(1, r1) + stw r9,0(r1) /* perform store component of stwu */ +#ifdef CONFIG_BOOKE + mfspr r9, SPRN_SPRG_RSCRATCH0 +#else + mfspr r9, SPRN_SPRG_SCRATCH0 +#endif + rfi +#ifdef CONFIG_40x + b . /* Prevent prefetch past rfi */ +#endif +_ASM_NOKPROBE_SYMBOL(interrupt_return) + +#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE) /* * Returning from a critical interrupt in user mode doesn't need @@ -642,8 +549,7 @@ _ASM_NOKPROBE_SYMBOL(exc_exit_restart) REST_NVGPRS(r1); \ lwz r3,_MSR(r1); \ andi. r3,r3,MSR_PR; \ - LOAD_REG_IMMEDIATE(r10,MSR_KERNEL); \ - bne user_exc_return; \ + bne interrupt_return; \ lwz r0,GPR0(r1); \ lwz r2,GPR2(r1); \ REST_4GPRS(3, r1); \ @@ -746,114 +652,8 @@ ret_from_mcheck_exc: RET_FROM_EXC_LEVEL(SPRN_MCSRR0, SPRN_MCSRR1, PPC_RFMCI) _ASM_NOKPROBE_SYMBOL(ret_from_mcheck_exc) #endif /* CONFIG_BOOKE */ - -/* - * Load the DBCR0 value for a task that is being ptraced, - * having first saved away the global DBCR0. Note that r0 - * has the dbcr0 value to set upon entry to this. - */ -load_dbcr0: - mfmsr r10 /* first disable debug exceptions */ - rlwinm r10,r10,0,~MSR_DE - mtmsr r10 - isync - mfspr r10,SPRN_DBCR0 - lis r11,global_dbcr0@ha - addi r11,r11,global_dbcr0@l -#ifdef CONFIG_SMP - lwz r9,TASK_CPU(r2) - slwi r9,r9,2 - add r11,r11,r9 -#endif - stw r10,0(r11) - mtspr SPRN_DBCR0,r0 - li r11,-1 - mtspr SPRN_DBSR,r11 /* clear all pending debug events */ - blr - - .section .bss - .align 4 - .global global_dbcr0 -global_dbcr0: - .space 4*NR_CPUS - .previous #endif /* !(CONFIG_4xx || CONFIG_BOOKE) */ -do_work: /* r10 contains MSR_KERNEL here */ - andi. r0,r9,_TIF_NEED_RESCHED - beq do_user_signal - -do_resched: /* r10 contains MSR_KERNEL here */ -#ifdef CONFIG_TRACE_IRQFLAGS - bl trace_hardirqs_on - mfmsr r10 -#endif - ori r10,r10,MSR_EE - mtmsr r10 /* hard-enable interrupts */ - bl schedule -recheck: - /* Note: And we don't tell it we are disabling them again - * neither. Those disable/enable cycles used to peek at - * TI_FLAGS aren't advertised. - */ - LOAD_REG_IMMEDIATE(r10,MSR_KERNEL) - mtmsr r10 /* disable interrupts */ - lwz r9,TI_FLAGS(r2) - andi. r0,r9,_TIF_NEED_RESCHED - bne- do_resched - andi. r0,r9,_TIF_USER_WORK_MASK - beq restore_user -do_user_signal: /* r10 contains MSR_KERNEL here */ - ori r10,r10,MSR_EE - mtmsr r10 /* hard-enable interrupts */ -2: addi r3,r1,STACK_FRAME_OVERHEAD - mr r4,r9 - bl do_notify_resume - REST_NVGPRS(r1) - b recheck - -/* - * We come here when we are at the end of handling an exception - * that occurred at a place where taking an exception will lose - * state information, such as the contents of SRR0 and SRR1. - */ -nonrecoverable: - lis r10,exc_exit_restart_end@ha - addi r10,r10,exc_exit_restart_end@l - cmplw r12,r10 - bge 3f - lis r11,exc_exit_restart@ha - addi r11,r11,exc_exit_restart@l - cmplw r12,r11 - blt 3f - lis r10,ee_restarts@ha - lwz r12,ee_restarts@l(r10) - addi r12,r12,1 - stw r12,ee_restarts@l(r10) - mr r12,r11 /* restart at exc_exit_restart */ - blr -3: /* OK, we can't recover, kill this process */ - lwz r3,_TRAP(r1) - andi. r0,r3,1 - beq 5f - SAVE_NVGPRS(r1) - rlwinm r3,r3,0,0,30 - stw r3,_TRAP(r1) -5: mfspr r2,SPRN_SPRG_THREAD - addi r2,r2,-THREAD - tovirt(r2,r2) /* set back r2 to current */ -4: addi r3,r1,STACK_FRAME_OVERHEAD - bl unrecoverable_exception - /* shouldn't return */ - b 4b -_ASM_NOKPROBE_SYMBOL(nonrecoverable) - - .section .bss - .align 2 -ee_restarts: - .space 4 - .previous - /* * PROM code for specific machines follows. Put it * here so it's easy to add arch-specific sections later. diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c index c475a229a42a..6875b82f613a 100644 --- a/arch/powerpc/kernel/interrupt.c +++ b/arch/powerpc/kernel/interrupt.c @@ -20,6 +20,10 @@ #include #include +#if defined(CONFIG_PPC_ADV_DEBUG_REGS) && defined(CONFIG_PPC32) +unsigned long global_dbcr0[NR_CPUS]; +#endif + typedef long (*syscall_fn)(long, long, long, long, long, long); /* Has to run notrace because it is entered not completely "reconciled" */ @@ -392,7 +396,7 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned ti_flags = READ_ONCE(current_thread_info()->flags); } - if (IS_ENABLED(CONFIG_PPC_BOOK3S) && IS_ENABLED(CONFIG_PPC_FPU)) { + if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && IS_ENABLED(CONFIG_PPC_FPU)) { if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && unlikely((ti_flags & _TIF_RESTORE_TM))) { restore_tm_state(regs);