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[v5,4/7] powerpc/64s: Move system_call() symbol to just after setting MSR_EE

Message ID bb13da48308f169c8f4ab889484a75b2af14ee7a.1498755960.git.naveen.n.rao@linux.vnet.ibm.com (mailing list archive)
State Accepted
Commit 266de3a842d70b481ef1dac487acfad1240deb7e
Headers show

Commit Message

Naveen N. Rao June 29, 2017, 5:49 p.m. UTC 
It is common to get a PMU interrupt right after the mtmsr instruction that
enables interrupts. Due to this, the stack trace profile gets needlessly split
across system_call_common() and system_call().

Previously, system_call() symbol was at the current place to hide a few
earlier symbols which have since been made private or removed entirely.

So, let's move system_call() slightly higher up, right after the mtmsr
instruction that enables interrupts. Convert existing references to
system_call to a local syscall symbol.

Suggested-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/entry_64.S | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
diff mbox

Patch

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index ef8e6615b8ba..c39436706555 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -142,6 +142,7 @@  END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR)
 	mtmsrd	r11,1
 #endif /* CONFIG_PPC_BOOK3E */
 
+system_call:			/* label this so stack traces look sane */
 	/* We do need to set SOFTE in the stack frame or the return
 	 * from interrupt will be painful
 	 */
@@ -155,7 +156,7 @@  END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR)
 	cmpldi	0,r0,NR_syscalls
 	bge-	.Lsyscall_enosys
 
-system_call:			/* label this so stack traces look sane */
+.Lsyscall:
 /*
  * Need to vector to 32 Bit or default sys_call_table here,
  * based on caller's run-mode / personality.
@@ -309,13 +310,13 @@  END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
 	ld	r7,GPR7(r1)
 	ld	r8,GPR8(r1)
 
-	/* Repopulate r9 and r10 for the system_call path */
+	/* Repopulate r9 and r10 for the syscall path */
 	addi	r9,r1,STACK_FRAME_OVERHEAD
 	CURRENT_THREAD_INFO(r10, r1)
 	ld	r10,TI_FLAGS(r10)
 
 	cmpldi	r0,NR_syscalls
-	blt+	system_call
+	blt+	.Lsyscall
 
 	/* Return code is already in r3 thanks to do_syscall_trace_enter() */
 	b	.Lsyscall_exit