[PATCH v4 22/23] powerpc/syscall: Optimise checks in beginning of system_call_exception()
From: Christophe Leroy <hidden>
Date: 2021-01-25 15:04:59
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
Combine all tests of regs->msr into a single logical one. Before the patch: 0: 81 6a 00 84 lwz r11,132(r10) 4: 90 6a 00 88 stw r3,136(r10) 8: 69 60 00 02 xori r0,r11,2 c: 54 00 ff fe rlwinm r0,r0,31,31,31 10: 0f 00 00 00 twnei r0,0 14: 69 63 40 00 xori r3,r11,16384 18: 54 63 97 fe rlwinm r3,r3,18,31,31 1c: 0f 03 00 00 twnei r3,0 20: 69 6b 80 00 xori r11,r11,32768 24: 55 6b 8f fe rlwinm r11,r11,17,31,31 28: 0f 0b 00 00 twnei r11,0 After the patch: 0: 81 6a 00 84 lwz r11,132(r10) 4: 90 6a 00 88 stw r3,136(r10) 8: 7d 6b 58 f8 not r11,r11 c: 71 6b c0 02 andi. r11,r11,49154 10: 0f 0b 00 00 twnei r11,0 6 cycles less on powerpc 8xx (328 => 322 cycles). Signed-off-by: Christophe Leroy <redacted> --- arch/powerpc/kernel/syscall.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/kernel/syscall.c b/arch/powerpc/kernel/syscall.c
index a40775daa88b..47ae55f94d1c 100644
--- a/arch/powerpc/kernel/syscall.c
+++ b/arch/powerpc/kernel/syscall.c@@ -28,6 +28,7 @@ notrace long system_call_exception(long r3, long r4, long r5, unsigned long r0, struct pt_regs *regs) { syscall_fn f; + unsigned long expected_msr; regs->orig_gpr3 = r3;
@@ -39,10 +40,13 @@ notrace long system_call_exception(long r3, long r4, long r5, trace_hardirqs_off(); /* finish reconciling */ + expected_msr = MSR_PR; if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x)) - BUG_ON(!(regs->msr & MSR_RI)); - BUG_ON(!(regs->msr & MSR_PR)); - BUG_ON(arch_irq_disabled_regs(regs)); + expected_msr |= MSR_RI; + if (IS_ENABLED(CONFIG_PPC32)) + expected_msr |= MSR_EE; + BUG_ON((regs->msr & expected_msr) ^ expected_msr); + BUG_ON(IS_ENABLED(CONFIG_PPC64) && arch_irq_disabled_regs(regs)); #ifdef CONFIG_PPC_PKEY if (mmu_has_feature(MMU_FTR_PKEY)) {
--
2.25.0