Commit 2652f9a4 authored by Jens Remus's avatar Jens Remus Committed by Peter Zijlstra
Browse files

unwind_user/fp: Use dummies instead of ifdef 



This simplifies the code.   unwind_user_next_fp() does not need to
return -EINVAL if config option HAVE_UNWIND_USER_FP is disabled, as
unwind_user_start() will then not select this unwind method and
unwind_user_next() will therefore not call it.

Provide (1) a dummy definition of ARCH_INIT_USER_FP_FRAME, if the unwind
user method HAVE_UNWIND_USER_FP is not enabled, (2) a common fallback
definition of unwind_user_at_function_start() which returns false, and
(3) a common dummy definition of ARCH_INIT_USER_FP_ENTRY_FRAME.

Note that enabling the config option HAVE_UNWIND_USER_FP without
defining ARCH_INIT_USER_FP_FRAME triggers a compile error, which is
helpful when implementing support for this unwind user method in an
architecture.  Enabling the config option when providing an arch-
specific unwind_user_at_function_start() definition makes it necessary
to also provide an arch-specific ARCH_INIT_USER_FP_ENTRY_FRAME
definition.

Signed-off-by: default avatarJens Remus <jremus@linux.ibm.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251208160352.1363040-3-jremus@linux.ibm.com
parent 2d6ad925

arch/x86/include/asm/unwind_user.h

+1 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ static inline bool unwind_user_at_function_start(struct pt_regs *regs) 
{

	return is_uprobe_at_func_entry(regs);

}

#define unwind_user_at_function_start unwind_user_at_function_start



#endif /* CONFIG_HAVE_UNWIND_USER_FP */

include/linux/unwind_user.h

+16 −2
Original line number Diff line number Diff line
@@ -5,8 +5,22 @@ 
#include <linux/unwind_user_types.h>

#include <asm/unwind_user.h>



#ifndef ARCH_INIT_USER_FP_FRAME

 #define ARCH_INIT_USER_FP_FRAME

#ifndef CONFIG_HAVE_UNWIND_USER_FP



#define ARCH_INIT_USER_FP_FRAME(ws)



#endif



#ifndef ARCH_INIT_USER_FP_ENTRY_FRAME

#define ARCH_INIT_USER_FP_ENTRY_FRAME(ws)

#endif



#ifndef unwind_user_at_function_start

static inline bool unwind_user_at_function_start(struct pt_regs *regs)

{

	return false;

}

#define unwind_user_at_function_start unwind_user_at_function_start

#endif



int unwind_user(struct unwind_stacktrace *trace, unsigned int max_entries);

kernel/unwind/user.c

+0 −4
Original line number Diff line number Diff line
@@ -67,7 +67,6 @@ static int unwind_user_next_common(struct unwind_user_state *state, 


static int unwind_user_next_fp(struct unwind_user_state *state)

{

#ifdef CONFIG_HAVE_UNWIND_USER_FP

	struct pt_regs *regs = task_pt_regs(current);



	if (state->topmost && unwind_user_at_function_start(regs)) {
@@ -81,9 +80,6 @@ static int unwind_user_next_fp(struct unwind_user_state *state) 
		ARCH_INIT_USER_FP_FRAME(state->ws)

	};

	return unwind_user_next_common(state, &fp_frame);

#else

	return -EINVAL;

#endif

}



static int unwind_user_next(struct unwind_user_state *state)