[PATCH v5 15/22] powerpc/32: Remove verification of MSR_PR on syscall in the ASM entry
From: Christophe Leroy <hidden>
Date: 2021-02-08 16:38:06
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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 <redacted> --- arch/powerpc/kernel/entry_32.S | 30 ------------------------------ arch/powerpc/kernel/head_32.h | 3 --- arch/powerpc/kernel/head_booke.h | 3 --- 3 files changed, 36 deletions(-)
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index bbf7ecea6fe0..cffe58e63356 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S@@ -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
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index fea7fe00a690..282d8fd443a9 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h@@ -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
diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
index db931f1167aa..bfbd240cc8a2 100644
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h@@ -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
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2.25.0