[PATCH 04/11] objtool: Convert instrumentation_{begin,end}() to ANNOTATE

Peter Zijlstra
2023-12-04T09:40:32Z

include/linux/instrumentation.h | 11 +++-----
include/linux/objtool.h | 9 ++++--
include/linux/objtool_types.h | 2 +
tools/include/linux/objtool_types.h | 2 +
tools/objtool/check.c | 49 +++++++-----------------------------
5 files changed, 25 insertions(+), 48 deletions(-)

--- a/include/linux/instrumentation.h
+++ b/include/linux/instrumentation.h
@@ -4,14 +4,14 @@

#ifdef CONFIG_NOINSTR_VALIDATION

+#include <linux/objtool.h>
#include <linux/stringify.h>

/* Begin/end of an instrumentation safe region */
#define __instrumentation_begin(c) ({ \
asm volatile(__stringify(c) ": nop\n\t" \
- ".pushsection .discard.instr_begin\n\t" \
- ".long " __stringify(c) "b - .\n\t" \
- ".popsection\n\t" : : "i" (c)); \
+ __ASM_ANNOTATE(c, ANNOTYPE_INSTR_BEGIN) \
+ : : "i" (c)); \
})
#define instrumentation_begin() __instrumentation_begin(__COUNTER__)

@@ -48,9 +48,8 @@
*/
#define __instrumentation_end(c) ({ \
asm volatile(__stringify(c) ": nop\n\t" \
- ".pushsection .discard.instr_end\n\t" \
- ".long " __stringify(c) "b - .\n\t" \
- ".popsection\n\t" : : "i" (c)); \
+ __ASM_ANNOTATE(c, ANNOTYPE_INSTR_END) \
+ : : "i" (c)); \
})
#define instrumentation_end() __instrumentation_end(__COUNTER__)
#else /* !CONFIG_NOINSTR_VALIDATION */
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -51,13 +51,16 @@
".long 998b\n\t" \
".popsection\n\t"

-#define ASM_ANNOTATE(x) \
- "911:\n\t" \
+#define __ASM_ANNOTATE(s, x) \
".pushsection .discard.annotate,\"M\",@progbits,8\n\t" \
- ".long 911b - .\n\t" \
+ ".long " __stringify(s) "b - .\n\t" \
".long " __stringify(x) "\n\t" \
".popsection\n\t"

+#define ASM_ANNOTATE(x) \
+ "911:\n\t" \
+ __ASM_ANNOTATE(911, x)
+
#define ANNOTATE_NOENDBR ASM_ANNOTATE(ANNOTYPE_NOENDBR)

#else /* __ASSEMBLY__ */
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -59,5 +59,7 @@ struct unwind_hint {
*/
#define ANNOTYPE_NOENDBR 1
#define ANNOTYPE_RETPOLINE_SAFE 2
+#define ANNOTYPE_INSTR_BEGIN 3
+#define ANNOTYPE_INSTR_END 4

#endif /* _LINUX_OBJTOOL_TYPES_H */
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -59,5 +59,7 @@ struct unwind_hint {
*/
#define ANNOTYPE_NOENDBR 1
#define ANNOTYPE_RETPOLINE_SAFE 2
+#define ANNOTYPE_INSTR_BEGIN 3
+#define ANNOTYPE_INSTR_END 4

#endif /* _LINUX_OBJTOOL_TYPES_H */
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2367,48 +2367,19 @@ static int __annotate_retpoline_safe(int
return 0;
}

-static int read_instr_hints(struct objtool_file *file)
+static int __annotate_instr(int type, struct instruction *insn)
{
- struct section *rsec;
- struct instruction *insn;
- struct reloc *reloc;
-
- rsec = find_section_by_name(file->elf, ".rela.discard.instr_end");
- if (!rsec)
- return 0;
-
- for_each_reloc(rsec, reloc) {
- if (reloc->sym->type != STT_SECTION) {
- WARN("unexpected relocation symbol type in %s", rsec->name);
- return -1;
- }
-
- insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
- if (!insn) {
- WARN("bad .discard.instr_end entry");
- return -1;
- }
+ switch (type) {
+ case ANNOTYPE_INSTR_BEGIN:
+ insn->instr++;
+ break;

+ case ANNOTYPE_INSTR_END:
insn->instr--;
- }
-
- rsec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
- if (!rsec)
- return 0;
+ break;

- for_each_reloc(rsec, reloc) {
- if (reloc->sym->type != STT_SECTION) {
- WARN("unexpected relocation symbol type in %s", rsec->name);
- return -1;
- }
-
- insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
- if (!insn) {
- WARN("bad .discard.instr_begin entry");
- return -1;
- }
-
- insn->instr++;
+ default:
+ break;
}

return 0;
@@ -2654,7 +2625,7 @@ static int decode_sections(struct objtoo
if (ret)
return ret;

- ret = read_instr_hints(file);
+ ret = read_annotate(file, __annotate_instr);
if (ret)
return ret;