In preparation for klp-build, enable "classic" objtool to work on
livepatch modules:
- Avoid duplicate symbol/section warnings for prefix symbols and the
.static_call_sites and __mcount_loc sections which may have already
been extracted by klp diff.
- Add __klp_funcs to the IBT function pointer section whitelist.
- Prevent KLP symbols from getting incorrectly classified as cold
subfunctions.
Signed-off-by: Josh Poimboeuf <jpoim...@kernel.org>
---
tools/objtool/check.c | 52 ++++++++++++++++++++++---
tools/objtool/elf.c | 5 ++-
tools/objtool/include/objtool/elf.h | 1 +
tools/objtool/include/objtool/objtool.h | 2 +-
4 files changed, 53 insertions(+), 7 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 6a9ce090a2cde..ba591a325d52e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3,6 +3,7 @@
* Copyright (C) 2015-2017 Josh Poimboeuf <jpoim...@redhat.com>
*/
+#define _GNU_SOURCE /* memmem() */
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
@@ -611,6 +612,20 @@ static int init_pv_ops(struct objtool_file *file)
return 0;
}
+static bool is_livepatch_module(struct objtool_file *file)
+{
+ struct section *sec;
+
+ if (!opts.module)
+ return false;
+
+ sec = find_section_by_name(file->elf, ".modinfo");
+ if (!sec)
+ return false;
+
+ return memmem(sec->data->d_buf, sec_size(sec), "\0livepatch=Y", 12);
+}
+
static int create_static_call_sections(struct objtool_file *file)
{
struct static_call_site *site;
@@ -622,7 +637,14 @@ static int create_static_call_sections(struct objtool_file
*file)
sec = find_section_by_name(file->elf, ".static_call_sites");
if (sec) {
- WARN("file already has .static_call_sites section, skipping");
+ /*
+ * Livepatch modules may have already extracted the static call
+ * site entries to take advantage of vmlinux static call
+ * privileges.
+ */
+ if (!file->klp)
+ WARN("file already has .static_call_sites section,
skipping");
+
return 0;
}
@@ -666,7 +688,7 @@ static int create_static_call_sections(struct objtool_file
*file)
key_sym = find_symbol_by_name(file->elf, tmp);
if (!key_sym) {
- if (!opts.module) {
+ if (!opts.module || file->klp) {
ERROR("static_call: can't find static_call_key
symbol: %s", tmp);
return -1;
}
@@ -885,7 +907,13 @@ static int create_mcount_loc_sections(struct objtool_file
*file)
sec = find_section_by_name(file->elf, "__mcount_loc");
if (sec) {
- WARN("file already has __mcount_loc section, skipping");
+ /*
+ * Livepatch modules have already extracted their __mcount_loc
+ * entries to cover the !CONFIG_FTRACE_MCOUNT_USE_OBJTOOL case.
+ */
+ if (!file->klp)
+ WARN("file already has __mcount_loc section, skipping");
+
return 0;
}
@@ -2579,6 +2607,8 @@ static bool validate_branch_enabled(void)
static int decode_sections(struct objtool_file *file)
{
+ file->klp = is_livepatch_module(file);
+
mark_rodata(file);
if (init_pv_ops(file))
@@ -4254,6 +4284,9 @@ static bool ignore_unreachable_insn(struct objtool_file
*file, struct instructio
* - compiler cloned functions (*.cold, *.part0, etc)
* - asm functions created with inline asm or without SYM_FUNC_START()
*
+ * Also, the function may already have a prefix from a previous objtool run
+ * (livepatch extracted functions, or manually running objtool multiple times).
+ *
* So return 0 if the NOPs are missing or the function already has a prefix
* symbol.
*/
@@ -4276,6 +4309,14 @@ static int create_prefix_symbol(struct objtool_file
*file, struct symbol *func)
if (snprintf_check(name, SYM_NAME_LEN, "__pfx_%s", func->name))
return -1;
+ if (file->klp) {
+ struct symbol *pfx;
+
+ pfx = find_symbol_by_offset(func->sec, func->offset -
opts.prefix);
+ if (pfx && is_prefix_func(pfx) && !strcmp(pfx->name, name))
+ return 0;
+ }
+
insn = find_insn(file, func->sec, func->offset);
if (!insn) {
WARN("%s: can't find starting instruction", func->name);
@@ -4628,6 +4669,7 @@ static int validate_ibt(struct objtool_file *file)
!strncmp(sec->name, ".debug", 6) ||
!strcmp(sec->name, ".altinstructions") ||
!strcmp(sec->name, ".ibt_endbr_seal") ||
+ !strcmp(sec->name, ".kcfi_traps") ||
!strcmp(sec->name, ".orc_unwind_ip") ||
!strcmp(sec->name, ".retpoline_sites") ||
!strcmp(sec->name, ".smp_locks") ||
@@ -4637,12 +4679,12 @@ static int validate_ibt(struct objtool_file *file)
!strcmp(sec->name, "__bug_table") ||
!strcmp(sec->name, "__ex_table") ||
!strcmp(sec->name, "__jump_table") ||
+ !strcmp(sec->name, "__klp_funcs") ||
!strcmp(sec->name, "__mcount_loc") ||
- !strcmp(sec->name, ".kcfi_traps") ||
!strcmp(sec->name, ".llvm.call-graph-profile") ||
!strcmp(sec->name, ".llvm_bb_addr_map") ||
!strcmp(sec->name, "__tracepoints") ||
- strstr(sec->name, "__patchable_function_entries"))
+ !strcmp(sec->name, "__patchable_function_entries"))
continue;
for_each_reloc(sec->rsec, reloc)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 4bb7ce994b6a7..5feeefc7fc8f8 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -499,7 +499,10 @@ static int elf_add_symbol(struct elf *elf, struct symbol
*sym)
strstarts(sym->name, "__pi___cfi_")))
sym->prefix = 1;
- if (is_func_sym(sym) && strstr(sym->name, ".cold"))
+ if (strstarts(sym->name, ".klp.sym"))
+ sym->klp = 1;
+
+ if (!sym->klp && is_func_sym(sym) && strstr(sym->name, ".cold"))
sym->cold = 1;
sym->pfunc = sym->cfunc = sym;
diff --git a/tools/objtool/include/objtool/elf.h
b/tools/objtool/include/objtool/elf.h
index 60f844e43c5a2..21d8b825fd8f0 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -88,6 +88,7 @@ struct symbol {
u8 debug_checksum : 1;
u8 changed : 1;
u8 included : 1;
+ u8 klp : 1;
struct list_head pv_target;
struct reloc *relocs;
struct section *group_sec;
diff --git a/tools/objtool/include/objtool/objtool.h
b/tools/objtool/include/objtool/objtool.h
index 7f70b41d1b8db..f7051bbe0bcb2 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -28,7 +28,7 @@ struct objtool_file {
struct list_head mcount_loc_list;
struct list_head endbr_list;
struct list_head call_list;
- bool ignore_unreachables, hints, rodata;
+ bool ignore_unreachables, hints, rodata, klp;
unsigned int nr_endbr;
unsigned int nr_endbr_int;
--
2.50.0
