6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Josh Poimboeuf jpoimboe@kernel.org
[ Upstream commit 7c977393b8277ed319e92e4b598b26598c9d30c0 ]
If 'regs' points to a local stack variable, prepare_frametrace() stores all registers to the stack. This confuses objtool as it expects them to be restored from the stack later.
The stores don't affect stack tracing, so use unwind hints to hide them from objtool.
Fixes the following warnings:
arch/loongarch/kernel/traps.o: warning: objtool: show_stack+0xe0: stack state mismatch: reg1[22]=-1+0 reg2[22]=-2-160 arch/loongarch/kernel/traps.o: warning: objtool: show_stack+0xe0: stack state mismatch: reg1[23]=-1+0 reg2[23]=-2-152
Fixes: cb8a2ef0848c ("LoongArch: Add ORC stack unwinder support") Reported-by: kernel test robot lkp@intel.com Tested-by: Tiezhu Yang yangtiezhu@loongson.cn Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Ingo Molnar mingo@kernel.org Cc: Linus Torvalds torvalds@linux-foundation.org Link: https://lore.kernel.org/r/270cadd8040dda74db2307f23497bb68e65db98d.174348153... Closes: https://lore.kernel.org/oe-kbuild-all/202503280703.OARM8SrY-lkp@intel.com/ Signed-off-by: Sasha Levin sashal@kernel.org --- arch/loongarch/include/asm/stacktrace.h | 3 +++ arch/loongarch/include/asm/unwind_hints.h | 10 +++++++++- 2 files changed, 12 insertions(+), 1 deletion(-)
diff --git a/arch/loongarch/include/asm/stacktrace.h b/arch/loongarch/include/asm/stacktrace.h index f23adb15f418f..fc8b64773794a 100644 --- a/arch/loongarch/include/asm/stacktrace.h +++ b/arch/loongarch/include/asm/stacktrace.h @@ -8,6 +8,7 @@ #include <asm/asm.h> #include <asm/ptrace.h> #include <asm/loongarch.h> +#include <asm/unwind_hints.h> #include <linux/stringify.h>
enum stack_type { @@ -43,6 +44,7 @@ int get_stack_info(unsigned long stack, struct task_struct *task, struct stack_i static __always_inline void prepare_frametrace(struct pt_regs *regs) { __asm__ __volatile__( + UNWIND_HINT_SAVE /* Save $ra */ STORE_ONE_REG(1) /* Use $ra to save PC */ @@ -80,6 +82,7 @@ static __always_inline void prepare_frametrace(struct pt_regs *regs) STORE_ONE_REG(29) STORE_ONE_REG(30) STORE_ONE_REG(31) + UNWIND_HINT_RESTORE : "=m" (regs->csr_era) : "r" (regs->regs) : "memory"); diff --git a/arch/loongarch/include/asm/unwind_hints.h b/arch/loongarch/include/asm/unwind_hints.h index a01086ad9ddea..2c68bc72736c9 100644 --- a/arch/loongarch/include/asm/unwind_hints.h +++ b/arch/loongarch/include/asm/unwind_hints.h @@ -23,6 +23,14 @@ UNWIND_HINT sp_reg=ORC_REG_SP type=UNWIND_HINT_TYPE_CALL .endm
-#endif /* __ASSEMBLY__ */ +#else /* !__ASSEMBLY__ */ + +#define UNWIND_HINT_SAVE \ + UNWIND_HINT(UNWIND_HINT_TYPE_SAVE, 0, 0, 0) + +#define UNWIND_HINT_RESTORE \ + UNWIND_HINT(UNWIND_HINT_TYPE_RESTORE, 0, 0, 0) + +#endif /* !__ASSEMBLY__ */
#endif /* _ASM_LOONGARCH_UNWIND_HINTS_H */