This is a note to let you know that I've just added the patch titled
tools/nolibc: fix up startup failures for -O0 under gcc < 11.1.0
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tools-nolibc-fix-up-startup-failures-for-o0-under-gc.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b31f45b8e224e0508612e325da41895e1ebb7a45
Author: Zhangjin Wu <falcon@xxxxxxxxxxx>
Date: Sun Jul 16 02:18:54 2023 +0800
tools/nolibc: fix up startup failures for -O0 under gcc < 11.1.0
[ Upstream commit bff60150f7c464d80d86f289c056c2ad2afb3c05 ]
As gcc doc [1] shows:
Most optimizations are completely disabled at -O0 or if an -O level is
not set on the command line, even if individual optimization flags are
specified.
Test result [2] shows, gcc>=11.1.0 deviates from the above description,
but before gcc 11.1.0, "-O0" still forcely uses frame pointer in the
_start function even if the individual optimize("omit-frame-pointer")
flag is specified.
The frame pointer related operations will change the stack pointer (e.g.
In x86_64, an extra "push %rbp" will be inserted at the beginning of
_start) and make it differs from the one we expected, as a result, break
the whole startup function.
To fix up this issue, as suggested by Thomas, the individual "Os" and
"omit-frame-pointer" optimize flags are used together on _start function
to disable frame pointer completely even if the -O0 is set on the
command line.
[1]: https://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html
[2]: https://lore.kernel.org/lkml/20230714094723.140603-1-falcon@xxxxxxxxxxx/
Suggested-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/lkml/34b21ba5-7b59-4b3b-9ed6-ef9a3a5e06f7@xxxxxxxx/
Fixes: 7f8548589661 ("tools/nolibc: make compiler and assembler agree on the section around _start")
Signed-off-by: Zhangjin Wu <falcon@xxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/include/nolibc/arch-aarch64.h b/tools/include/nolibc/arch-aarch64.h
index aaafe8a75c8ee..b8c7b14c4ca85 100644
--- a/tools/include/nolibc/arch-aarch64.h
+++ b/tools/include/nolibc/arch-aarch64.h
@@ -175,7 +175,7 @@ char **environ __attribute__((weak));
const unsigned long *_auxv __attribute__((weak));
/* startup code */
-void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
#ifdef _NOLIBC_STACKPROTECTOR
diff --git a/tools/include/nolibc/arch-arm.h b/tools/include/nolibc/arch-arm.h
index 7ae6f68594882..bd8bf2ebd43bf 100644
--- a/tools/include/nolibc/arch-arm.h
+++ b/tools/include/nolibc/arch-arm.h
@@ -225,7 +225,7 @@ char **environ __attribute__((weak));
const unsigned long *_auxv __attribute__((weak));
/* startup code */
-void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
#ifdef _NOLIBC_STACKPROTECTOR
diff --git a/tools/include/nolibc/arch-i386.h b/tools/include/nolibc/arch-i386.h
index 853cf77633d90..1a86f86eab5c5 100644
--- a/tools/include/nolibc/arch-i386.h
+++ b/tools/include/nolibc/arch-i386.h
@@ -190,7 +190,7 @@ const unsigned long *_auxv __attribute__((weak));
* 2) The deepest stack frame should be set to zero
*
*/
-void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
#ifdef _NOLIBC_STACKPROTECTOR
diff --git a/tools/include/nolibc/arch-loongarch.h b/tools/include/nolibc/arch-loongarch.h
index 3f96271d9a63a..b0279b9411785 100644
--- a/tools/include/nolibc/arch-loongarch.h
+++ b/tools/include/nolibc/arch-loongarch.h
@@ -172,7 +172,7 @@ const unsigned long *_auxv __attribute__((weak));
#endif
/* startup code */
-void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
#ifdef _NOLIBC_STACKPROTECTOR
diff --git a/tools/include/nolibc/arch-mips.h b/tools/include/nolibc/arch-mips.h
index f031cf9dbf31f..67c5d79971107 100644
--- a/tools/include/nolibc/arch-mips.h
+++ b/tools/include/nolibc/arch-mips.h
@@ -182,7 +182,7 @@ char **environ __attribute__((weak));
const unsigned long *_auxv __attribute__((weak));
/* startup code, note that it's called __start on MIPS */
-void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector __start(void)
+void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector __start(void)
{
__asm__ volatile (
/*".set nomips16\n"*/
diff --git a/tools/include/nolibc/arch-riscv.h b/tools/include/nolibc/arch-riscv.h
index 6da31dcd2e737..cefefc2e93f18 100644
--- a/tools/include/nolibc/arch-riscv.h
+++ b/tools/include/nolibc/arch-riscv.h
@@ -180,7 +180,7 @@ char **environ __attribute__((weak));
const unsigned long *_auxv __attribute__((weak));
/* startup code */
-void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
".option push\n"
diff --git a/tools/include/nolibc/arch-s390.h b/tools/include/nolibc/arch-s390.h
index 293801221678c..ed2c33b2de68b 100644
--- a/tools/include/nolibc/arch-s390.h
+++ b/tools/include/nolibc/arch-s390.h
@@ -166,7 +166,7 @@ char **environ __attribute__((weak));
const unsigned long *_auxv __attribute__((weak));
/* startup code */
-void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
"lg %r2,0(%r15)\n" /* argument count */
diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h
index 2a08bd75ff63b..1bbd95f652330 100644
--- a/tools/include/nolibc/arch-x86_64.h
+++ b/tools/include/nolibc/arch-x86_64.h
@@ -190,7 +190,7 @@ const unsigned long *_auxv __attribute__((weak));
* 2) The deepest stack frame should be zero (the %rbp).
*
*/
-void __attribute__((weak, noreturn, optimize("omit-frame-pointer"))) __no_stack_protector _start(void)
+void __attribute__((weak, noreturn, optimize("Os", "omit-frame-pointer"))) __no_stack_protector _start(void)
{
__asm__ volatile (
#ifdef _NOLIBC_STACKPROTECTOR
