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[193.116.110.116]) by smtp.gmail.com with ESMTPSA id o8sm4071453wmb.20.2020.06.11.05.11.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Jun 2020 05:11:29 -0700 (PDT) From: Nicholas Piggin To: linuxppc-dev@lists.ozlabs.org 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 Message-Id: <20200611121119.1015740-1-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nicholas Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 --- 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