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| author | Tiezhu Yang <yangtiezhu@loongson.cn> | 2025-10-02 17:38:57 +0300 |
|---|---|---|
| committer | Huacai Chen <chenhuacai@loongson.cn> | 2025-10-02 17:38:57 +0300 |
| commit | abb2a5572264b425e6dd9c213b735a82ab0ca68a (patch) | |
| tree | 776759c7c1d927b0515f98addf97afc23e980570 | |
| parent | 2b5f6638204cc0e0f6ecd55b963ebb895ec61f3b (diff) | |
| download | linux-abb2a5572264b425e6dd9c213b735a82ab0ca68a.tar.xz | |
LoongArch: Add cflag -fno-isolate-erroneous-paths-dereference
Currently, when compiling with GCC, there is no "break 7" instruction
for zero division due to using the option -mno-check-zero-division, but
the compiler still generates "break 0" instruction for zero division.
Here is a simple example:
$ cat test.c
int div(int a)
{
return a / 0;
}
$ gcc -O2 -S test.c -o test.s
GCC generates "break 0" on LoongArch and "ud2" on x86, objtool decodes
"ud2" as INSN_BUG for x86, so decode "break 0" as INSN_BUG can fix the
objtool warnings for LoongArch, but this is not the intention.
When decoding "break 0" as INSN_TRAP in the previous commit, the aim is
to handle "break 0" as a trap. The generated "break 0" for zero division
by GCC is not proper, it should generate a break instruction with proper
bug type, so add the GCC option -fno-isolate-erroneous-paths-dereference
to avoid generating the unexpected "break 0" instruction for now.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/r/202509200413.7uihAxJ5-lkp@intel.com/
Fixes: baad7830ee9a ("objtool/LoongArch: Mark types based on break immediate code")
Suggested-by: WANG Rui <wangrui@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
| -rw-r--r-- | arch/loongarch/Makefile | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile index ae419e32f22e..f2a585b4a937 100644 --- a/arch/loongarch/Makefile +++ b/arch/loongarch/Makefile @@ -129,7 +129,7 @@ KBUILD_RUSTFLAGS_KERNEL += -Crelocation-model=pie LDFLAGS_vmlinux += -static -pie --no-dynamic-linker -z notext $(call ld-option, --apply-dynamic-relocs) endif -cflags-y += $(call cc-option, -mno-check-zero-division) +cflags-y += $(call cc-option, -mno-check-zero-division -fno-isolate-erroneous-paths-dereference) ifndef CONFIG_KASAN cflags-y += -fno-builtin-memcpy -fno-builtin-memmove -fno-builtin-memset |