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Peter Anvin" , Dennis Zhou , Tejun Heo , Christoph Lameter , "Peter Zijlstra (Intel)" Subject: [PATCH v2 1/2] x86/locking: Use ALT_OUTPUT_SP() for percpu_{,try_}cmpxchg{64,128}_op() Date: Fri, 14 Feb 2025 16:07:46 +0100 Message-ID: <20250214150929.5780-1-ubizjak@gmail.com> X-Mailer: git-send-email 2.42.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit percpu_{,try_}cmpxchg{64,128}() macros use CALL instruction inside asm statement in one of their alternatives. Use ALT_OUTPUT_SP() macro to add required dependence on %esp register. ALT_OUTPUT_SP() implements the above dependence by adding ASM_CALL_CONSTRAINT to its arguments. This constraint should be used for any inline asm which has a CALL instruction, otherwise the compiler may schedule the asm before the frame pointer gets set up by the containing function, causing objtool to print a "call without frame pointer save/setup" warning. Signed-off-by: Uros Bizjak Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: Dennis Zhou Cc: Tejun Heo Cc: Christoph Lameter Cc: "Peter Zijlstra (Intel)" --- v2: Expand commit message with the explanation of ASM_CALL_CONSTRAINT. --- arch/x86/include/asm/percpu.h | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-) diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h index e525cd85f999..0ab991fba7de 100644 --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -350,9 +350,9 @@ do { \ \ asm qual (ALTERNATIVE("call this_cpu_cmpxchg8b_emu", \ "cmpxchg8b " __percpu_arg([var]), X86_FEATURE_CX8) \ - : [var] "+m" (__my_cpu_var(_var)), \ - "+a" (old__.low), \ - "+d" (old__.high) \ + : ALT_OUTPUT_SP([var] "+m" (__my_cpu_var(_var)), \ + "+a" (old__.low), \ + "+d" (old__.high)) \ : "b" (new__.low), \ "c" (new__.high), \ "S" (&(_var)) \ @@ -381,10 +381,10 @@ do { \ asm qual (ALTERNATIVE("call this_cpu_cmpxchg8b_emu", \ "cmpxchg8b " __percpu_arg([var]), X86_FEATURE_CX8) \ CC_SET(z) \ - : CC_OUT(z) (success), \ - [var] "+m" (__my_cpu_var(_var)), \ - "+a" (old__.low), \ - "+d" (old__.high) \ + : ALT_OUTPUT_SP(CC_OUT(z) (success), \ + [var] "+m" (__my_cpu_var(_var)), \ + "+a" (old__.low), \ + "+d" (old__.high)) \ : "b" (new__.low), \ "c" (new__.high), \ "S" (&(_var)) \ @@ -421,9 +421,9 @@ do { \ \ asm qual (ALTERNATIVE("call this_cpu_cmpxchg16b_emu", \ "cmpxchg16b " __percpu_arg([var]), X86_FEATURE_CX16) \ - : [var] "+m" (__my_cpu_var(_var)), \ - "+a" (old__.low), \ - "+d" (old__.high) \ + : ALT_OUTPUT_SP([var] "+m" (__my_cpu_var(_var)), \ + "+a" (old__.low), \ + "+d" (old__.high)) \ : "b" (new__.low), \ "c" (new__.high), \ "S" (&(_var)) \ @@ -452,10 +452,10 @@ do { \ asm qual (ALTERNATIVE("call this_cpu_cmpxchg16b_emu", \ "cmpxchg16b " __percpu_arg([var]), X86_FEATURE_CX16) \ CC_SET(z) \ - : CC_OUT(z) (success), \ - [var] "+m" (__my_cpu_var(_var)), \ - "+a" (old__.low), \ - "+d" (old__.high) \ + : ALT_OUTPUT_SP(CC_OUT(z) (success), \ + [var] "+m" (__my_cpu_var(_var)), \ + "+a" (old__.low), \ + "+d" (old__.high)) \ : "b" (new__.low), \ "c" (new__.high), \ "S" (&(_var)) \ -- 2.42.0