Commit 0bb080ba authored by Alexandre Chartre's avatar Alexandre Chartre Committed by Peter Zijlstra
Browse files

objtool: Disassemble instruction on warning or backtrace 



When an instruction warning (WARN_INSN) or backtrace (BT_INSN) is issued,
disassemble the instruction to provide more context.

Signed-off-by: default avatarAlexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Link: https://patch.msgid.link/20251121095340.464045-8-alexandre.chartre@oracle.com
parent d4e13c21

tools/objtool/check.c

+30 −6
Original line number Diff line number Diff line
@@ -4792,11 +4792,34 @@ static void free_insns(struct objtool_file *file) 
		free(chunk->addr);

}



static struct disas_context *objtool_disas_ctx;



const char *objtool_disas_insn(struct instruction *insn)

{

	struct disas_context *dctx = objtool_disas_ctx;



	if (!dctx)

		return "";



	disas_insn(dctx, insn);

	return disas_result(dctx);

}



int check(struct objtool_file *file)

{

	struct disas_context *disas_ctx;

	struct disas_context *disas_ctx = NULL;

	int ret = 0, warnings = 0;



	/*

	 * If the verbose or backtrace option is used then we need a

	 * disassembly context to disassemble instruction or function

	 * on warning or backtrace.

	 */

	if (opts.verbose || opts.backtrace) {

		disas_ctx = disas_context_create(file);

		objtool_disas_ctx = disas_ctx;

	}



	arch_initial_func_cfi_state(&initial_func_cfi);

	init_cfi_state(&init_cfi);

	init_cfi_state(&func_cfi);
@@ -4936,11 +4959,12 @@ int check(struct objtool_file *file) 
	if (opts.verbose) {

		if (opts.werror && warnings)

			WARN("%d warning(s) upgraded to errors", warnings);

		disas_ctx = disas_context_create(file);

		if (disas_ctx) {

		disas_warned_funcs(disas_ctx);

			disas_context_destroy(disas_ctx);

	}



	if (disas_ctx) {

		disas_context_destroy(disas_ctx);

		objtool_disas_ctx = NULL;

	}



	free_insns(file);

tools/objtool/disas.c

+2 −3
Original line number Diff line number Diff line
@@ -303,7 +303,7 @@ void disas_context_destroy(struct disas_context *dctx) 
	free(dctx);

}



static char *disas_result(struct disas_context *dctx)

char *disas_result(struct disas_context *dctx)

{

	return dctx->result;

}
@@ -311,8 +311,7 @@ static char *disas_result(struct disas_context *dctx) 
/*

 * Disassemble a single instruction. Return the size of the instruction.

 */

static size_t disas_insn(struct disas_context *dctx,

			 struct instruction *insn)

size_t disas_insn(struct disas_context *dctx, struct instruction *insn)

{

	disassembler_ftype disasm = dctx->disassembler;

	struct disassemble_info *dinfo = &dctx->info;

tools/objtool/include/objtool/check.h

+2 −0
Original line number Diff line number Diff line
@@ -141,4 +141,6 @@ struct instruction *next_insn_same_sec(struct objtool_file *file, struct instruc 
	     insn && insn->offset < sym->offset + sym->len;		\

	     insn = next_insn_same_sec(file, insn))



const char *objtool_disas_insn(struct instruction *insn);



#endif /* _CHECK_H */

tools/objtool/include/objtool/disas.h

+13 −0
Original line number Diff line number Diff line
@@ -17,6 +17,8 @@ void disas_warned_funcs(struct disas_context *dctx); 
int disas_info_init(struct disassemble_info *dinfo,

		    int arch, int mach32, int mach64,

		    const char *options);

size_t disas_insn(struct disas_context *dctx, struct instruction *insn);

char *disas_result(struct disas_context *dctx);



#else /* DISAS */
@@ -38,6 +40,17 @@ static inline int disas_info_init(struct disassemble_info *dinfo, 
	return -1;

}



static inline size_t disas_insn(struct disas_context *dctx,

				struct instruction *insn)

{

	return -1;

}



static inline char *disas_result(struct disas_context *dctx)

{

	return NULL;

}



#endif /* DISAS */



#endif /* _DISAS_H */

tools/objtool/include/objtool/warn.h

+11 −5
Original line number Diff line number Diff line
@@ -77,9 +77,11 @@ static inline char *offstr(struct section *sec, unsigned long offset) 
#define WARN_INSN(insn, format, ...)					\

({									\

	struct instruction *_insn = (insn);				\

	if (!_insn->sym || !_insn->sym->warned)				\

	if (!_insn->sym || !_insn->sym->warned)	{			\

		WARN_FUNC(_insn->sec, _insn->offset, format,		\

			  ##__VA_ARGS__);				\

		BT_INSN(_insn, "");					\

	}								\

	if (_insn->sym)							\

		_insn->sym->warned = 1;					\

})
@@ -87,9 +89,13 @@ static inline char *offstr(struct section *sec, unsigned long offset) 
#define BT_INSN(insn, format, ...)				\

({								\

	if (opts.verbose || opts.backtrace) {			\

		struct instruction *_insn = (insn);		\

		char *_str = offstr(_insn->sec, _insn->offset); \

		WARN("  %s: " format, _str, ##__VA_ARGS__);	\

		struct instruction *__insn = (insn);		\

		char *_str = offstr(__insn->sec, __insn->offset); \

		const char *_istr = objtool_disas_insn(__insn);	\

		int _len;					\

		_len = snprintf(NULL, 0, "  %s: " format,  _str, ##__VA_ARGS__);	\

		_len = (_len < 50) ? 50 - _len : 0;		\

		WARN("  %s: " format "  %*s%s", _str, ##__VA_ARGS__, _len, "", _istr); \

		free(_str);						\

	}							\

})