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objtool/klp: Disable unsupported pr_debug() usage

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Instead of erroring out on unsupported pr_debug() (e.g., when patching a
module), issue a warning and make it inert, similar to how unsupported
tracepoints are currently handled.

Reviewed-and-tested-by: Song Liu <song@kernel.org>
Link: https://patch.msgid.link/3a7db3a5b7d4abf9b2534803a74e2e7231322738.1770759954.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
This commit is contained in:
Josh Poimboeuf
2026-02-10 13:50:10 -08:00
parent f9fb44b0ec
commit e476bb277c
1 changed files with 15 additions and 8 deletions
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23
tools/objtool/klp-diff.c
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@@ -1334,18 +1334,18 @@ static bool should_keep_special_sym(struct elf *elf, struct symbol *sym)
* be applied after static branch/call init, resulting in code corruption.
*
* Validate a special section entry to avoid that. Note that an inert
* tracepoint is harmless enough, in that case just skip the entry and print a
* warning. Otherwise, return an error.
* tracepoint or pr_debug() is harmless enough, in that case just skip the
* entry and print a warning. Otherwise, return an error.
*
* This is only a temporary limitation which will be fixed when livepatch adds
* support for submodules: fully self-contained modules which are embedded in
* the top-level livepatch module's data and which can be loaded on demand when
* their corresponding to-be-patched module gets loaded. Then klp relocs can
* be retired.
* TODO: This is only a temporary limitation which will be fixed when livepatch
* adds support for submodules: fully self-contained modules which are embedded
* in the top-level livepatch module's data and which can be loaded on demand
* when their corresponding to-be-patched module gets loaded. Then klp relocs
* can be retired.
*
* Return:
* -1: error: validation failed
* 1: warning: tracepoint skipped
* 1: warning: disabled tracepoint or pr_debug()
* 0: success
*/
static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym)
@@ -1403,6 +1403,13 @@ static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym
continue;
}
if (strstr(reloc->sym->name, "__UNIQUE_ID_ddebug_")) {
WARN("%s: disabling unsupported pr_debug()",
code_sym->name);
ret = 1;
continue;
}
ERROR("%s+0x%lx: unsupported static branch key %s. Use static_key_enabled() instead",
code_sym->name, code_offset, reloc->sym->name);
return -1;