[RFC WIP PATCH] powerpc/32: system call implement entry/exit logic in C

Christophe Leroy christophe.leroy at c-s.fr
Wed Apr 1 22:48:09 AEDT 2020



Le 31/03/2020 à 17:22, Christophe Leroy a écrit :
> That's first try to port PPC64 syscall entry/exit logic in C to PPC32.
> I've do the minimum to get it work. I have not reworked calls
> to sys_fork() and friends for instance.
> 
> For the time being, it seems to work more or less but:
> - ping reports EINVAL on recvfrom
> - strace shows NULL instead of strings in call like open() for instance.

For the two above problems, that's because system_call_exception() 
doesn't set orig_gpr3 whereas DoSycall() does in entry_32.S . Is that 
only done on PPC32 ?

With the following line at the begining of system_call_exception(), it 
works perfectly:

	regs->orig_gpr3 = r3;

I will now focus on performance to see if we can do something about it.

Christophe

> - the performance is definitively bad
> 
> On an 8xx, null_syscall test is about 30% slower after this patch:
> - Without the patch: 284 cycles
> - With the patch: 371 cycles
> 
> @nick and others, any suggestion to fix and improve ?
> 
> Signed-off-by: Christophe Leroy <christophe.leroy at c-s.fr>
> ---
>   arch/powerpc/include/asm/book3s/32/kup.h      |  21 ++
>   .../powerpc/include/asm/book3s/64/kup-radix.h |  12 +-
>   arch/powerpc/include/asm/hw_irq.h             |  15 +
>   arch/powerpc/include/asm/kup.h                |   2 +
>   arch/powerpc/include/asm/nohash/32/kup-8xx.h  |  13 +
>   arch/powerpc/kernel/Makefile                  |   5 +-
>   arch/powerpc/kernel/entry_32.S                | 259 ++----------------
>   arch/powerpc/kernel/head_32.h                 |   3 +-
>   .../kernel/{syscall_64.c => syscall.c}        |  25 +-
>   9 files changed, 102 insertions(+), 253 deletions(-)
>   rename arch/powerpc/kernel/{syscall_64.c => syscall.c} (97%)
> 
> diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
> index 3c0ba22dc360..c85bc5b56366 100644
> --- a/arch/powerpc/include/asm/book3s/32/kup.h
> +++ b/arch/powerpc/include/asm/book3s/32/kup.h
> @@ -102,6 +102,27 @@ static inline void kuap_update_sr(u32 sr, u32 addr, u32 end)
>   	isync();	/* Context sync required after mtsrin() */
>   }
>   
> +static inline void kuap_restore(struct pt_regs *regs)
> +{
> +	u32 kuap = current->thread.kuap;
> +	u32 addr = kuap & 0xf0000000;
> +	u32 end = kuap << 28;
> +
> +	if (unlikely(!kuap))
> +		return;
> +
> +	current->thread.kuap = 0;
> +	kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end);	/* Clear Ks */
> +}
> +
> +static inline void kuap_check(void)
> +{
> +	if (!IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))
> +		return;
> +
> +	WARN_ON_ONCE(current->thread.kuap != 0);
> +}
> +
>   static __always_inline void allow_user_access(void __user *to, const void __user *from,
>   					      u32 size, unsigned long dir)
>   {
> diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h b/arch/powerpc/include/asm/book3s/64/kup-radix.h
> index 3bcef989a35d..1f2716a0dcd8 100644
> --- a/arch/powerpc/include/asm/book3s/64/kup-radix.h
> +++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h
> @@ -60,13 +60,13 @@
>   #include <asm/mmu.h>
>   #include <asm/ptrace.h>
>   
> -static inline void kuap_restore_amr(struct pt_regs *regs)
> +static inline void kuap_restore(struct pt_regs *regs)
>   {
>   	if (mmu_has_feature(MMU_FTR_RADIX_KUAP))
>   		mtspr(SPRN_AMR, regs->kuap);
>   }
>   
> -static inline void kuap_check_amr(void)
> +static inline void kuap_check(void)
>   {
>   	if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG) && mmu_has_feature(MMU_FTR_RADIX_KUAP))
>   		WARN_ON_ONCE(mfspr(SPRN_AMR) != AMR_KUAP_BLOCKED);
> @@ -141,14 +141,6 @@ bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
>   		    (regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)),
>   		    "Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read");
>   }
> -#else /* CONFIG_PPC_KUAP */
> -static inline void kuap_restore_amr(struct pt_regs *regs)
> -{
> -}
> -
> -static inline void kuap_check_amr(void)
> -{
> -}
>   #endif /* CONFIG_PPC_KUAP */
>   
>   #endif /* __ASSEMBLY__ */
> diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h
> index e0e71777961f..6ccf07de6665 100644
> --- a/arch/powerpc/include/asm/hw_irq.h
> +++ b/arch/powerpc/include/asm/hw_irq.h
> @@ -321,6 +321,16 @@ static inline void arch_local_irq_disable(void)
>   		mtmsr(mfmsr() & ~MSR_EE);
>   }
>   
> +static inline void arch_local_recovery_disable(void)
> +{
> +	if (IS_ENABLED(CONFIG_BOOKE))
> +		wrtee(0);
> +	else if (IS_ENABLED(CONFIG_PPC_8xx))
> +		wrtspr(SPRN_NRI);
> +	else
> +		mtmsr(mfmsr() & ~(MSR_EE | MSR_RI));
> +}
> +
>   static inline void arch_local_irq_enable(void)
>   {
>   	if (IS_ENABLED(CONFIG_BOOKE))
> @@ -343,6 +353,11 @@ static inline bool arch_irqs_disabled(void)
>   
>   #define hard_irq_disable()		arch_local_irq_disable()
>   
> +#define __hard_irq_enable()		arch_local_irq_enable()
> +#define __hard_irq_disable()		arch_local_irq_disable()
> +#define __hard_EE_RI_disable()		arch_local_recovery_disable()
> +#define __hard_RI_enable()		arch_local_irq_disable()
> +
>   static inline bool arch_irq_disabled_regs(struct pt_regs *regs)
>   {
>   	return !(regs->msr & MSR_EE);
> diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h
> index 92bcd1a26d73..1100c13b6d9e 100644
> --- a/arch/powerpc/include/asm/kup.h
> +++ b/arch/powerpc/include/asm/kup.h
> @@ -62,6 +62,8 @@ bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
>   {
>   	return false;
>   }
> +static inline void kuap_restore(struct pt_regs *regs) { }
> +static inline void kuap_check(void) { }
>   #endif /* CONFIG_PPC_KUAP */
>   
>   static inline void allow_read_from_user(const void __user *from, unsigned long size)
> diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
> index 85ed2390fb99..1918d2e55da3 100644
> --- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h
> +++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h
> @@ -34,6 +34,19 @@
>   
>   #include <asm/reg.h>
>   
> +static inline void kuap_restore(struct pt_regs *regs)
> +{
> +	mtspr(SPRN_MD_AP, regs->kuap);
> +}
> +
> +static inline void kuap_check(void)
> +{
> +	if (!IS_ENABLED(CONFIG_PPC_KUAP_DEBUG))
> +		return;
> +
> +	WARN_ON_ONCE((mfspr(SPRN_MD_AP) & 0xffff0000) != (MD_APG_KUAP & 0xffff0000));
> +}
> +
>   static inline void allow_user_access(void __user *to, const void __user *from,
>   				     unsigned long size, unsigned long dir)
>   {
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index 570660efbb3d..e4be425b7718 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -45,11 +45,10 @@ obj-y				:= cputable.o syscalls.o \
>   				   signal.o sysfs.o cacheinfo.o time.o \
>   				   prom.o traps.o setup-common.o \
>   				   udbg.o misc.o io.o misc_$(BITS).o \
> -				   of_platform.o prom_parse.o
> +				   of_platform.o prom_parse.o syscall.o
>   obj-y				+= ptrace/
>   obj-$(CONFIG_PPC64)		+= setup_64.o sys_ppc32.o signal_64.o \
> -				   paca.o nvram_64.o firmware.o note.o \
> -				   syscall_64.o
> +				   paca.o nvram_64.o firmware.o note.o
>   obj-$(CONFIG_VDSO32)		+= vdso32/
>   obj-$(CONFIG_PPC_WATCHDOG)	+= watchdog.o
>   obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o
> diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
> index a6371fb8f761..103f5158bc44 100644
> --- a/arch/powerpc/kernel/entry_32.S
> +++ b/arch/powerpc/kernel/entry_32.S
> @@ -315,162 +315,37 @@ stack_ovf:
>   	RFI
>   #endif
>   
> -#ifdef CONFIG_TRACE_IRQFLAGS
> -trace_syscall_entry_irq_off:
> -	/*
> -	 * Syscall shouldn't happen while interrupts are disabled,
> -	 * so let's do a warning here.
> -	 */
> -0:	trap
> -	EMIT_BUG_ENTRY 0b,__FILE__,__LINE__, BUGFLAG_WARNING
> -	bl	trace_hardirqs_on
> -
> -	/* Now enable for real */
> -	LOAD_REG_IMMEDIATE(r10, MSR_KERNEL | MSR_EE)
> -	mtmsr	r10
> -
> -	REST_GPR(0, r1)
> -	REST_4GPRS(3, r1)
> -	REST_2GPRS(7, r1)
> -	b	DoSyscall
> -#endif /* CONFIG_TRACE_IRQFLAGS */
> -
>   	.globl	transfer_to_syscall
>   transfer_to_syscall:
> -#ifdef CONFIG_TRACE_IRQFLAGS
> -	andi.	r12,r9,MSR_EE
> -	beq-	trace_syscall_entry_irq_off
> -#endif /* CONFIG_TRACE_IRQFLAGS */
> -
> -/*
> - * Handle a system call.
> - */
> -	.stabs	"arch/powerpc/kernel/",N_SO,0,0,0f
> -	.stabs	"entry_32.S",N_SO,0,0,0f
> -0:
> -
> -_GLOBAL(DoSyscall)
> -	stw	r3,ORIG_GPR3(r1)
> -	li	r12,0
> -	stw	r12,RESULT(r1)
> -#ifdef CONFIG_TRACE_IRQFLAGS
> -	/* Make sure interrupts are enabled */
> -	mfmsr	r11
> -	andi.	r12,r11,MSR_EE
> -	/* We came in with interrupts disabled, we WARN and mark them enabled
> -	 * for lockdep now */
> -0:	tweqi	r12, 0
> -	EMIT_BUG_ENTRY 0b,__FILE__,__LINE__, BUGFLAG_WARNING
> -#endif /* CONFIG_TRACE_IRQFLAGS */
> -	lwz	r11,TI_FLAGS(r2)
> -	andi.	r11,r11,_TIF_SYSCALL_DOTRACE
> -	bne-	syscall_dotrace
> -syscall_dotrace_cont:
> -	cmplwi	0,r0,NR_syscalls
> -	lis	r10,sys_call_table at h
> -	ori	r10,r10,sys_call_table at l
> -	slwi	r0,r0,2
> -	bge-	66f
> -
> -	barrier_nospec_asm
> -	/*
> -	 * Prevent the load of the handler below (based on the user-passed
> -	 * system call number) being speculatively executed until the test
> -	 * against NR_syscalls and branch to .66f above has
> -	 * committed.
> -	 */
> -
> -	lwzx	r10,r10,r0	/* Fetch system call handler [ptr] */
> -	mtlr	r10
> -	addi	r9,r1,STACK_FRAME_OVERHEAD
> -	PPC440EP_ERR42
> -	blrl			/* Call handler */
> -	.globl	ret_from_syscall
> +	mr	r9, r0
> +	addi	r10, r1, STACK_FRAME_OVERHEAD
> +	bl	system_call_exception
>   ret_from_syscall:
> -#ifdef CONFIG_DEBUG_RSEQ
> -	/* Check whether the syscall is issued inside a restartable sequence */
> -	stw	r3,GPR3(r1)
> -	addi    r3,r1,STACK_FRAME_OVERHEAD
> -	bl      rseq_syscall
> -	lwz	r3,GPR3(r1)
> -#endif
> -	mr	r6,r3
> -	/* disable interrupts so current_thread_info()->flags can't change */
> -	LOAD_REG_IMMEDIATE(r10,MSR_KERNEL)	/* doesn't include MSR_EE */
> -	/* Note: We don't bother telling lockdep about it */
> -	SYNC
> -	mtmsr	r10
> -	lwz	r9,TI_FLAGS(r2)
> -	li	r8,-MAX_ERRNO
> -	andi.	r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP|_TIF_USER_WORK_MASK|_TIF_PERSYSCALL_MASK)
> -	bne-	syscall_exit_work
> -	cmplw	0,r3,r8
> -	blt+	syscall_exit_cont
> -	lwz	r11,_CCR(r1)			/* Load CR */
> -	neg	r3,r3
> -	oris	r11,r11,0x1000	/* Set SO bit in CR */
> -	stw	r11,_CCR(r1)
> -syscall_exit_cont:
> -	lwz	r8,_MSR(r1)
> -#ifdef CONFIG_TRACE_IRQFLAGS
> -	/* If we are going to return from the syscall with interrupts
> -	 * off, we trace that here. It shouldn't normally happen.
> -	 */
> -	andi.	r10,r8,MSR_EE
> -	bne+	1f
> -	stw	r3,GPR3(r1)
> -	bl      trace_hardirqs_off
> -	lwz	r3,GPR3(r1)
> -1:
> -#endif /* CONFIG_TRACE_IRQFLAGS */
> -#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
> -	/* If the process has its own DBCR0 value, load it up.  The internal
> -	   debug mode bit tells us that dbcr0 should be loaded. */
> -	lwz	r0,THREAD+THREAD_DBCR0(r2)
> -	andis.	r10,r0,DBCR0_IDM at h
> -	bnel-	load_dbcr0
> -#endif
> -#ifdef CONFIG_44x
> -BEGIN_MMU_FTR_SECTION
> -	lis	r4,icache_44x_need_flush at ha
> -	lwz	r5,icache_44x_need_flush at l(r4)
> -	cmplwi	cr0,r5,0
> -	bne-	2f
> -1:
> -END_MMU_FTR_SECTION_IFCLR(MMU_FTR_TYPE_47x)
> -#endif /* CONFIG_44x */
> -BEGIN_FTR_SECTION
> -	lwarx	r7,0,r1
> -END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRED_STWCX)
> -	stwcx.	r0,0,r1			/* to clear the reservation */
> -	ACCOUNT_CPU_USER_EXIT(r2, r5, r7)
> -#ifdef CONFIG_PPC_BOOK3S_32
> -	kuep_unlock r5, r7
> -#endif
> -	kuap_check r2, r4
> -	lwz	r4,_LINK(r1)
> -	lwz	r5,_CCR(r1)
> -	mtlr	r4
> -	mtcr	r5
> -	lwz	r7,_NIP(r1)
> -	lwz	r2,GPR2(r1)
> -	lwz	r1,GPR1(r1)
> -#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)
> -	mtspr	SPRN_NRI, r0
> -#endif
> -	mtspr	SPRN_SRR0,r7
> -	mtspr	SPRN_SRR1,r8
> -	SYNC
> -	RFI
> -#ifdef CONFIG_44x
> -2:	li	r7,0
> -	iccci	r0,r0
> -	stw	r7,icache_44x_need_flush at l(r4)
> +	addi    r4, r1, STACK_FRAME_OVERHEAD
> +	bl	syscall_exit_prepare
> +	lwz	r2, _CCR(r1)
> +	lwz	r4, _NIP(r1)
> +	lwz	r5, _MSR(r1)
> +	lwz	r6, _LINK(r1)
> +	mtspr	SPRN_SRR0, r4
> +	mtspr	SPRN_SRR1, r5
> +	mtlr	r6
> +	cmpwi	r3, 0
> +	bne	2f
> +1:	mtcr	r2
> +	REST_GPR(2, r1)
> +	REST_GPR(3, r1)
> +	REST_GPR(1, r1)
> +	rfi
> +2:	lwz	r3, _CTR(r1)
> +	lwz	r4, _XER(r1)
> +	REST_NVGPRS(r1)
> +	mtctr	r3
> +	mtspr	SPRN_XER, r4
> +	REST_GPR(0, r1)
> +	REST_8GPRS(4, r1)
> +	REST_GPR(12, r1)
>   	b	1b
> -#endif  /* CONFIG_44x */
> -
> -66:	li	r3,-ENOSYS
> -	b	ret_from_syscall
>   
>   	.globl	ret_from_fork
>   ret_from_fork:
> @@ -490,86 +365,6 @@ ret_from_kernel_thread:
>   	li	r3,0
>   	b	ret_from_syscall
>   
> -/* Traced system call support */
> -syscall_dotrace:
> -	SAVE_NVGPRS(r1)
> -	li	r0,0xc00
> -	stw	r0,_TRAP(r1)
> -	addi	r3,r1,STACK_FRAME_OVERHEAD
> -	bl	do_syscall_trace_enter
> -	/*
> -	 * Restore argument registers possibly just changed.
> -	 * We use the return value of do_syscall_trace_enter
> -	 * for call number to look up in the table (r0).
> -	 */
> -	mr	r0,r3
> -	lwz	r3,GPR3(r1)
> -	lwz	r4,GPR4(r1)
> -	lwz	r5,GPR5(r1)
> -	lwz	r6,GPR6(r1)
> -	lwz	r7,GPR7(r1)
> -	lwz	r8,GPR8(r1)
> -	REST_NVGPRS(r1)
> -
> -	cmplwi	r0,NR_syscalls
> -	/* Return code is already in r3 thanks to do_syscall_trace_enter() */
> -	bge-	ret_from_syscall
> -	b	syscall_dotrace_cont
> -
> -syscall_exit_work:
> -	andi.	r0,r9,_TIF_RESTOREALL
> -	beq+	0f
> -	REST_NVGPRS(r1)
> -	b	2f
> -0:	cmplw	0,r3,r8
> -	blt+	1f
> -	andi.	r0,r9,_TIF_NOERROR
> -	bne-	1f
> -	lwz	r11,_CCR(r1)			/* Load CR */
> -	neg	r3,r3
> -	oris	r11,r11,0x1000	/* Set SO bit in CR */
> -	stw	r11,_CCR(r1)
> -
> -1:	stw	r6,RESULT(r1)	/* Save result */
> -	stw	r3,GPR3(r1)	/* Update return value */
> -2:	andi.	r0,r9,(_TIF_PERSYSCALL_MASK)
> -	beq	4f
> -
> -	/* Clear per-syscall TIF flags if any are set.  */
> -
> -	li	r11,_TIF_PERSYSCALL_MASK
> -	addi	r12,r2,TI_FLAGS
> -3:	lwarx	r8,0,r12
> -	andc	r8,r8,r11
> -#ifdef CONFIG_IBM405_ERR77
> -	dcbt	0,r12
> -#endif
> -	stwcx.	r8,0,r12
> -	bne-	3b
> -	
> -4:	/* Anything which requires enabling interrupts? */
> -	andi.	r0,r9,(_TIF_SYSCALL_DOTRACE|_TIF_SINGLESTEP)
> -	beq	ret_from_except
> -
> -	/* Re-enable interrupts. There is no need to trace that with
> -	 * lockdep as we are supposed to have IRQs on at this point
> -	 */
> -	ori	r10,r10,MSR_EE
> -	SYNC
> -	mtmsr	r10
> -
> -	/* Save NVGPRS if they're not saved already */
> -	lwz	r4,_TRAP(r1)
> -	andi.	r4,r4,1
> -	beq	5f
> -	SAVE_NVGPRS(r1)
> -	li	r4,0xc00
> -	stw	r4,_TRAP(r1)
> -5:
> -	addi	r3,r1,STACK_FRAME_OVERHEAD
> -	bl	do_syscall_trace_leave
> -	b	ret_from_except_full
> -
>   	/*
>   	 * System call was called from kernel. We get here with SRR1 in r9.
>   	 * Mark the exception as recoverable once we have retrieved SRR0,
> diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
> index 9abec6cd099c..97691931a306 100644
> --- a/arch/powerpc/kernel/head_32.h
> +++ b/arch/powerpc/kernel/head_32.h
> @@ -174,12 +174,13 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
>   	stw	r2,GPR2(r11)
>   	addi	r10,r10,STACK_FRAME_REGS_MARKER at l
>   	stw	r9,_MSR(r11)
> -	li	r2, \trapno + 1
> +	li	r2, \trapno
>   	stw	r10,8(r11)
>   	stw	r2,_TRAP(r11)
>   	SAVE_GPR(0, r11)
>   	SAVE_4GPRS(3, r11)
>   	SAVE_2GPRS(7, r11)
> +	SAVE_NVGPRS(r11)
>   	addi	r11,r1,STACK_FRAME_OVERHEAD
>   	addi	r2,r12,-THREAD
>   	stw	r11,PT_REGS(r12)
> diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall.c
> similarity index 97%
> rename from arch/powerpc/kernel/syscall_64.c
> rename to arch/powerpc/kernel/syscall.c
> index cf06eb443a80..a07702a85f81 100644
> --- a/arch/powerpc/kernel/syscall_64.c
> +++ b/arch/powerpc/kernel/syscall.c
> @@ -1,8 +1,9 @@
>   // SPDX-License-Identifier: GPL-2.0-or-later
>   
>   #include <linux/err.h>
> +#include <linux/compat.h>
> +
>   #include <asm/asm-prototypes.h>
> -#include <asm/book3s/64/kup-radix.h>
>   #include <asm/cputime.h>
>   #include <asm/hw_irq.h>
>   #include <asm/kprobes.h>
> @@ -25,16 +26,20 @@ notrace long system_call_exception(long r3, long r4, long r5,
>   	unsigned long ti_flags;
>   	syscall_fn f;
>   
> +#ifdef CONFIG_PPC64
>   	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
>   		BUG_ON(irq_soft_mask_return() != IRQS_ALL_DISABLED);
> +#endif
>   
>   	trace_hardirqs_off(); /* finish reconciling */
>   
> -	if (IS_ENABLED(CONFIG_PPC_BOOK3S))
> +	if (!IS_ENABLED(CONFIG_PPC_BOOK3E))
>   		BUG_ON(!(regs->msr & MSR_RI));
>   	BUG_ON(!(regs->msr & MSR_PR));
>   	BUG_ON(!FULL_REGS(regs));
> +#ifdef CONFIG_PPC64
>   	BUG_ON(regs->softe != IRQS_ENABLED);
> +#endif
>   
>   	account_cpu_user_entry();
>   
> @@ -48,7 +53,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
>   	}
>   #endif
>   
> -	kuap_check_amr();
> +	kuap_check();
>   
>   	/*
>   	 * This is not required for the syscall exit path, but makes the
> @@ -56,7 +61,9 @@ notrace long system_call_exception(long r3, long r4, long r5,
>   	 * frame, or if the unwinder was taught the first stack frame always
>   	 * returns to user with IRQS_ENABLED, this store could be avoided!
>   	 */
> +#ifdef CONFIG_PPC64
>   	regs->softe = IRQS_ENABLED;
> +#endif
>   
>   	local_irq_enable();
>   
> @@ -86,7 +93,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
>   	/* May be faster to do array_index_nospec? */
>   	barrier_nospec();
>   
> -	if (unlikely(ti_flags & _TIF_32BIT)) {
> +	if (is_compat_task()) {
>   		f = (void *)compat_sys_call_table[r0];
>   
>   		r3 &= 0x00000000ffffffffULL;
> @@ -148,7 +155,9 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
>   		ret |= _TIF_RESTOREALL;
>   	}
>   
> +#ifdef CONFIG_PPC64
>   again:
> +#endif
>   	local_irq_disable();
>   	ti_flags = READ_ONCE(*ti_flagsp);
>   	while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) {
> @@ -191,6 +200,7 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
>   
>   	/* This pattern matches prep_irq_for_idle */
>   	__hard_EE_RI_disable();
> +#ifdef CONFIG_PPC64
>   	if (unlikely(lazy_irq_pending())) {
>   		__hard_RI_enable();
>   		trace_hardirqs_off();
> @@ -201,12 +211,13 @@ notrace unsigned long syscall_exit_prepare(unsigned long r3,
>   	}
>   	local_paca->irq_happened = 0;
>   	irq_soft_mask_set(IRQS_ENABLED);
> +#endif
>   
>   #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
>   	local_paca->tm_scratch = regs->msr;
>   #endif
>   
> -	kuap_check_amr();
> +	kuap_check();
>   
>   	account_cpu_user_exit();
>   
> @@ -294,7 +305,7 @@ notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs, unsigned
>   	local_paca->tm_scratch = regs->msr;
>   #endif
>   
> -	kuap_check_amr();
> +	kuap_check();
>   
>   	account_cpu_user_exit();
>   
> @@ -372,7 +383,7 @@ notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs, unsign
>   	 * We don't need to restore AMR on the way back to userspace for KUAP.
>   	 * The value of AMR only matters while we're in the kernel.
>   	 */
> -	kuap_restore_amr(regs);
> +	kuap_restore(regs);
>   
>   	return ret;
>   }
> 


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