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objtool: Add functions to better name alternatives

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Add the disas_alt_name() and disas_alt_type_name() to provide a
name and a type name for an alternative. This will be used to
better name alternatives when tracing their execution.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://patch.msgid.link/20251121095340.464045-15-alexandre.chartre@oracle.com
This commit is contained in:
Alexandre Chartre
2025-11-21 10:53:24 +01:00
committed by Peter Zijlstra
parent d490aa2197
commit 9b580accac
2 changed files with 84 additions and 0 deletions
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72
tools/objtool/disas.c
View File

@@ -3,6 +3,8 @@
* Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
*/
#define _GNU_SOURCE
#include <objtool/arch.h>
#include <objtool/check.h>
#include <objtool/disas.h>
@@ -450,6 +452,76 @@ size_t disas_insn(struct disas_context *dctx, struct instruction *insn)
return disasm(insn->offset, &dctx->info);
}
/*
* Provide a name for the type of alternatives present at the
* specified instruction.
*
* An instruction can have alternatives with different types, for
* example alternative instructions and an exception table. In that
* case the name for the alternative instructions type is used.
*
* Return NULL if the instruction as no alternative.
*/
const char *disas_alt_type_name(struct instruction *insn)
{
struct alternative *alt;
const char *name;
name = NULL;
for (alt = insn->alts; alt; alt = alt->next) {
if (alt->type == ALT_TYPE_INSTRUCTIONS) {
name = "alternative";
break;
}
switch (alt->type) {
case ALT_TYPE_EX_TABLE:
name = "ex_table";
break;
case ALT_TYPE_JUMP_TABLE:
name = "jump_table";
break;
default:
name = "unknown";
break;
}
}
return name;
}
/*
* Provide a name for an alternative.
*/
char *disas_alt_name(struct alternative *alt)
{
char *str = NULL;
switch (alt->type) {
case ALT_TYPE_EX_TABLE:
str = strdup("EXCEPTION");
break;
case ALT_TYPE_JUMP_TABLE:
str = strdup("JUMP");
break;
case ALT_TYPE_INSTRUCTIONS:
/*
* This is a non-default group alternative. Create a unique
* name using the offset of the first original and alternative
* instructions.
*/
asprintf(&str, "ALTERNATIVE %lx.%lx",
alt->insn->alt_group->orig_group->first_insn->offset,
alt->insn->alt_group->first_insn->offset);
break;
}
return str;
}
/*
* Disassemble a function.
*/

12
tools/objtool/include/objtool/disas.h
View File

@@ -6,6 +6,7 @@
#ifndef _DISAS_H
#define _DISAS_H
struct alternative;
struct disas_context;
struct disassemble_info;
@@ -24,6 +25,8 @@ void disas_print_info(FILE *stream, struct instruction *insn, int depth,
void disas_print_insn(FILE *stream, struct disas_context *dctx,
struct instruction *insn, int depth,
const char *format, ...);
char *disas_alt_name(struct alternative *alt);
const char *disas_alt_type_name(struct instruction *insn);
#else /* DISAS */
@@ -61,6 +64,15 @@ static inline void disas_print_info(FILE *stream, struct instruction *insn,
static inline void disas_print_insn(FILE *stream, struct disas_context *dctx,
struct instruction *insn, int depth,
const char *format, ...) {}
static inline char *disas_alt_name(struct alternative *alt)
{
return NULL;
}
static inline const char *disas_alt_type_name(struct instruction *insn)
{
return NULL;
}
#endif /* DISAS */