From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH] powerpc/64: indirect function call use bctrl rather than blrl in ret_from_kernel_thread
Date: Thu, 11 Jun 2020 22:11:19 +1000 [thread overview]
Message-ID: <20200611121119.1015740-1-npiggin@gmail.com> (raw)
blrl is not recommended to use as an indirect function call, as it may
corrupt the link stack predictor.
This is not a performance critical path but this should be fixed for
consistency.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/entry_64.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 223c4f008e63..f59a17471d4d 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -400,12 +400,12 @@ _GLOBAL(ret_from_fork)
_GLOBAL(ret_from_kernel_thread)
bl schedule_tail
REST_NVGPRS(r1)
- mtlr r14
+ mtctr r14
mr r3,r15
#ifdef PPC64_ELF_ABI_v2
mr r12,r14
#endif
- blrl
+ bctrl
li r3,0
b .Lsyscall_exit
--
2.23.0
next reply other threads:[~2020-06-11 12:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-11 12:11 Nicholas Piggin [this message]
2020-06-11 12:26 ` [PATCH] powerpc/64: indirect function call use bctrl rather than blrl in ret_from_kernel_thread Christophe Leroy
2020-06-14 9:24 ` Nicholas Piggin
2020-06-26 4:46 ` Michael Ellerman
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