Commit 4d67facb authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/32: Remove verification of MSR_PR on syscall in the ASM entry 



system_call_exception() checks MSR_PR and BUGs if a syscall
is issued from kernel mode.

No need to handle it anymore from the ASM entry code.

null_syscall reduction 2 cycles (348 => 346 cycles)

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1eddb42cb12092b1e3d72608d182c365db3da41d.1612796617.git.christophe.leroy@csgroup.eu
parent 6f76a011

arch/powerpc/kernel/entry_32.S

+0 −30
Original line number Diff line number Diff line
@@ -421,36 +421,6 @@ ret_from_kernel_thread: 
	li	r3,0

	b	ret_from_syscall



	/*

	 * System call was called from kernel. We get here with SRR1 in r9.

	 * Mark the exception as recoverable once we have retrieved SRR0,

	 * trap a warning and return ENOSYS with CR[SO] set.

	 */

	.globl	ret_from_kernel_syscall

ret_from_kernel_syscall:

	mfspr	r9, SPRN_SRR0

	mfspr	r10, SPRN_SRR1

#if !defined(CONFIG_4xx) && !defined(CONFIG_BOOKE)

	LOAD_REG_IMMEDIATE(r11, MSR_KERNEL & ~(MSR_IR|MSR_DR))

	mtmsr	r11

#endif



0:	trap

	EMIT_BUG_ENTRY 0b,__FILE__,__LINE__, BUGFLAG_WARNING



	li	r3, ENOSYS

	crset	so

#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS)

	mtspr	SPRN_NRI, r0

#endif

	mtspr	SPRN_SRR0, r9

	mtspr	SPRN_SRR1, r10

	rfi

#ifdef CONFIG_40x

	b .	/* Prevent prefetch past rfi */

#endif

_ASM_NOKPROBE_SYMBOL(ret_from_kernel_syscall)



/*

 * Top-level page fault handling.

 * This is in assembler because if do_page_fault tells us that

arch/powerpc/kernel/head_32.h

+0 −3
Original line number Diff line number Diff line
@@ -118,8 +118,6 @@ 
.macro SYSCALL_ENTRY trapno

	mfspr	r9, SPRN_SRR1

	mfspr	r10, SPRN_SRR0

	andi.	r11, r9, MSR_PR

	beq-	99f

	LOAD_REG_IMMEDIATE(r11, MSR_KERNEL)		/* can take exceptions */

	lis	r12, 1f@h

	ori	r12, r12, 1f@l
@@ -174,7 +172,6 @@ 
3:

#endif

	b	transfer_to_syscall		/* jump to handler */

99:	b	ret_from_kernel_syscall

.endm



.macro save_dar_dsisr_on_stack reg1, reg2, sp

arch/powerpc/kernel/head_booke.h

+0 −3
Original line number Diff line number Diff line
@@ -106,10 +106,8 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV) 
#endif

	mfspr	r9, SPRN_SRR1

	BOOKE_CLEAR_BTB(r11)

	andi.	r11, r9, MSR_PR

	lwz	r11, TASK_STACK - THREAD(r10)

	rlwinm	r12,r12,0,4,2	/* Clear SO bit in CR */

	beq-	99f

	ALLOC_STACK_FRAME(r11, THREAD_SIZE - INT_FRAME_SIZE)

	stw	r12, _CCR(r11)		/* save various registers */

	mflr	r12
@@ -155,7 +153,6 @@ ALT_FTR_SECTION_END_IFSET(CPU_FTR_EMB_HV) 


3:

	b	transfer_to_syscall	/* jump to handler */

99:	b	ret_from_kernel_syscall

.endm



/* To handle the additional exception priority levels on 40x and Book-E