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kallsyms: cleanup code for appending the module buildid

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Put the code for appending the optional "buildid" into a helper function,
It makes __sprint_symbol() better readable.

Also print a warning when the "modname" is set and the "buildid" isn't. 
It might catch a situation when some lookup function in
kallsyms_lookup_buildid() does not handle the "buildid".

Use pr_*_once() to avoid an infinite recursion when the function is called
from printk().  The recursion is rather theoretical but better be on the
safe side.

Link: https://lkml.kernel.org/r/20251128135920.217303-5-pmladek@suse.com
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Aaron Tomlin <atomlin@atomlin.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Petr Mladek 2025-11-28 14:59:17 +01:00 committed by Andrew Morton
parent acfdbb4ab2
commit 8e81dac4cd
1 changed files with 33 additions and 9 deletions
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42
kernel/kallsyms.c
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@ -435,6 +435,37 @@ int lookup_symbol_name(unsigned long addr, char *symname)
return lookup_module_symbol_name(addr, symname);
}
#ifdef CONFIG_STACKTRACE_BUILD_ID
static int append_buildid(char *buffer, const char *modname,
const unsigned char *buildid)
{
if (!modname)
return 0;
if (!buildid) {
pr_warn_once("Undefined buildid for the module %s\n", modname);
return 0;
}
/* build ID should match length of sprintf */
#ifdef CONFIG_MODULES
static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
#endif
return sprintf(buffer, " %20phN", buildid);
}
#else /* CONFIG_STACKTRACE_BUILD_ID */
static int append_buildid(char *buffer, const char *modname,
const unsigned char *buildid)
{
return 0;
}
#endif /* CONFIG_STACKTRACE_BUILD_ID */
/* Look up a kernel symbol and return it in a text buffer. */
static int __sprint_symbol(char *buffer, unsigned long address,
int symbol_offset, int add_offset, int add_buildid)
@ -457,15 +488,8 @@ static int __sprint_symbol(char *buffer, unsigned long address,
if (modname) {
len += sprintf(buffer + len, " [%s", modname);
#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
if (add_buildid && buildid) {
/* build ID should match length of sprintf */
#if IS_ENABLED(CONFIG_MODULES)
static_assert(sizeof(typeof_member(struct module, build_id)) == 20);
#endif
len += sprintf(buffer + len, " %20phN", buildid);
}
#endif
if (add_buildid)
len += append_buildid(buffer + len, modname, buildid);
len += sprintf(buffer + len, "]");
}