From: Sathvika Vasireddy <sv@linux.ibm.com> To: linuxppc-dev@lists.ozlabs.org Cc: jpoimboe@redhat.com, peterz@infradead.org, linux-kernel@vger.kernel.org, aik@ozlabs.ru, mpe@ellerman.id.au, mingo@redhat.com, christophe.leroy@csgroup.eu, rostedt@goodmis.org, mbenes@suse.cz, npiggin@gmail.com, chenzhongjin@huawei.com, naveen.n.rao@linux.vnet.ibm.com, sv@linux.ibm.com Subject: [PATCH v6 01/16] powerpc: Fix __WARN_FLAGS() for use with Objtool Date: Mon, 14 Nov 2022 23:27:39 +0530 [thread overview] Message-ID: <20221114175754.1131267-2-sv@linux.ibm.com> (raw) In-Reply-To: <20221114175754.1131267-1-sv@linux.ibm.com> Commit 1e688dd2a3d675 ("powerpc/bug: Provide better flexibility to WARN_ON/__WARN_FLAGS() with asm goto") updated __WARN_FLAGS() to use asm goto, and added a call to 'unreachable()' after the asm goto for optimal code generation. With CONFIG_OBJTOOL enabled, 'annotate_unreachable()' statement in 'unreachable()' tries to note down the location of the subsequent instruction in a separate elf section to aid code flow analysis. However, on powerpc, this results in gcc emitting a call to a symbol of size 0. This results in objtool complaining of "unannotated intra-function call" since the target symbol is not a valid function call destination. Objtool wants this annotation for code flow analysis, which we are not yet enabling on powerpc. As such, expand the call to 'unreachable()' in __WARN_FLAGS() without annotate_unreachable(): barrier_before_unreachable(); __builtin_unreachable(); This still results in optimal code generation for __WARN_FLAGS(), while getting rid of the objtool warning. We still need barrier_before_unreachable() to work around gcc bugs 82365 and 106751: - https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 - https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106751 Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com> --- arch/powerpc/include/asm/bug.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h index 61a4736355c2..ef42adb44aa3 100644 --- a/arch/powerpc/include/asm/bug.h +++ b/arch/powerpc/include/asm/bug.h @@ -99,7 +99,8 @@ __label__ __label_warn_on; \ \ WARN_ENTRY("twi 31, 0, 0", BUGFLAG_WARNING | (flags), __label_warn_on); \ - unreachable(); \ + barrier_before_unreachable(); \ + __builtin_unreachable(); \ \ __label_warn_on: \ break; \ -- 2.31.1
WARNING: multiple messages have this Message-ID (diff)
From: Sathvika Vasireddy <sv@linux.ibm.com> To: linuxppc-dev@lists.ozlabs.org Cc: peterz@infradead.org, npiggin@gmail.com, linux-kernel@vger.kernel.org, aik@ozlabs.ru, mingo@redhat.com, sv@linux.ibm.com, rostedt@goodmis.org, jpoimboe@redhat.com, naveen.n.rao@linux.vnet.ibm.com, mbenes@suse.cz, chenzhongjin@huawei.com Subject: [PATCH v6 01/16] powerpc: Fix __WARN_FLAGS() for use with Objtool Date: Mon, 14 Nov 2022 23:27:39 +0530 [thread overview] Message-ID: <20221114175754.1131267-2-sv@linux.ibm.com> (raw) In-Reply-To: <20221114175754.1131267-1-sv@linux.ibm.com> Commit 1e688dd2a3d675 ("powerpc/bug: Provide better flexibility to WARN_ON/__WARN_FLAGS() with asm goto") updated __WARN_FLAGS() to use asm goto, and added a call to 'unreachable()' after the asm goto for optimal code generation. With CONFIG_OBJTOOL enabled, 'annotate_unreachable()' statement in 'unreachable()' tries to note down the location of the subsequent instruction in a separate elf section to aid code flow analysis. However, on powerpc, this results in gcc emitting a call to a symbol of size 0. This results in objtool complaining of "unannotated intra-function call" since the target symbol is not a valid function call destination. Objtool wants this annotation for code flow analysis, which we are not yet enabling on powerpc. As such, expand the call to 'unreachable()' in __WARN_FLAGS() without annotate_unreachable(): barrier_before_unreachable(); __builtin_unreachable(); This still results in optimal code generation for __WARN_FLAGS(), while getting rid of the objtool warning. We still need barrier_before_unreachable() to work around gcc bugs 82365 and 106751: - https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 - https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106751 Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com> --- arch/powerpc/include/asm/bug.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h index 61a4736355c2..ef42adb44aa3 100644 --- a/arch/powerpc/include/asm/bug.h +++ b/arch/powerpc/include/asm/bug.h @@ -99,7 +99,8 @@ __label__ __label_warn_on; \ \ WARN_ENTRY("twi 31, 0, 0", BUGFLAG_WARNING | (flags), __label_warn_on); \ - unreachable(); \ + barrier_before_unreachable(); \ + __builtin_unreachable(); \ \ __label_warn_on: \ break; \ -- 2.31.1
next prev parent reply other threads:[~2022-11-14 17:59 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-11-14 17:57 [PATCH v6 00/16] objtool: Enable and implement --mcount option on powerpc Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy [this message] 2022-11-14 17:57 ` [PATCH v6 01/16] powerpc: Fix __WARN_FLAGS() for use with Objtool Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 02/16] powerpc: Override __ALIGN and __ALIGN_STR macros Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 03/16] powerpc: Fix objtool unannotated intra-function call warnings Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 04/16] powerpc: Curb " Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 05/16] powerpc: Skip objtool from running on drivers/crypto/vmx/aesp8-ppc.o Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 06/16] powerpc: Fix objtool unannotated intra-function call warnings on PPC32 Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 07/16] powerpc: Skip objtool from running on VDSO files Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 08/16] objtool: Fix SEGFAULT Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 09/16] objtool: Use target file endianness instead of a compiled constant Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 10/16] objtool: Use target file class size " Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 11/16] objtool: Add --mnop as an option to --mcount Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 12/16] objtool: Read special sections with alts only when specific options are selected Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 13/16] objtool: Use macros to define arch specific reloc types Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 14/16] objtool: Add arch specific function arch_ftrace_match() Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 15/16] objtool/powerpc: Enable objtool to be built on ppc Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-11-14 17:57 ` [PATCH v6 16/16] objtool/powerpc: Add --mcount specific implementation Sathvika Vasireddy 2022-11-14 17:57 ` Sathvika Vasireddy 2022-12-08 13:02 ` [PATCH v6 00/16] objtool: Enable and implement --mcount option on powerpc Michael Ellerman 2022-12-08 13:02 ` Michael Ellerman
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