Commit 7c977393 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Ingo Molnar
Browse files

objtool/loongarch: Add unwind hints in prepare_frametrace() 



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: cb8a2ef0 ("LoongArch: Add ORC stack unwinder support")
Reported-by: default avatarkernel test robot <lkp@intel.com>
Tested-by: default avatarTiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/270cadd8040dda74db2307f23497bb68e65db98d.1743481539.git.jpoimboe@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202503280703.OARM8SrY-lkp@intel.com/
parent 6309a5c4

arch/loongarch/include/asm/stacktrace.h

+3 −0
Original line number Diff line number Diff line
@@ -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");

arch/loongarch/include/asm/unwind_hints.h

+9 −1
Original line number Diff line number Diff line
@@ -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 */