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

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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: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1eddb42cb12092b1e3d72608d182c365db3da41d.1612796617.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2021-02-08 15:10:34 +00:00 • committed by Michael Ellerman
parent 6f76a01173
commit 4d67facbcb
3 changed files with 0 additions and 36 deletions
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30
arch/powerpc/kernel/entry_32.S
View file

@ -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

3
arch/powerpc/kernel/head_32.h
View file

@ -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

3
arch/powerpc/kernel/head_booke.h
View file

@ -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