The '__unreachable' and '__func_stack_frame_non_standard' sections are
only used at compile time. They're discarded for vmlinux but they
should also be discarded for modules.
Since this is a recurring pattern, prefix the section names with
".discard.". It's a nice convention and vmlinux.lds.h already discards
such sections.
Also remove the 'a' (allocatable) flag from the __unreachable section
since it doesn't make sense for a discarded section.
Suggested-by: Linus Torvalds <torva...@linux-foundation.org>
Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead ends")
Signed-off-by: Josh Poimboeuf <jpoim...@redhat.com>
---
arch/x86/kernel/vmlinux.lds.S | 2 --
include/linux/compiler-gcc.h | 2 +-
include/linux/frame.h | 2 +-
scripts/mod/modpost.c | 1 +
scripts/module-common.lds | 5 ++++-
tools/objtool/builtin-check.c | 7 ++++---
6 files changed, 11 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index ad0118f..c74ae9c 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -345,8 +345,6 @@ SECTIONS
DISCARDS
/DISCARD/ : {
*(.eh_frame)
- *(__func_stack_frame_non_standard)
- *(__unreachable)
}
}
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index b6bb901..0efef9c 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -200,7 +200,7 @@
#ifdef CONFIG_STACK_VALIDATION
#define annotate_unreachable() ({ \
asm("%c0:\t\n" \
- ".pushsection __unreachable, \"a\"\t\n" \
+ ".pushsection .discard.unreachable\t\n" \
".long %c0b - .\t\n" \
".popsection\t\n" : : "i" (__LINE__)); \
})
diff --git a/include/linux/frame.h b/include/linux/frame.h
index e6baaba..d772c61 100644
--- a/include/linux/frame.h
+++ b/include/linux/frame.h
@@ -11,7 +11,7 @@
* For more information, see tools/objtool/Documentation/stack-validation.txt.
*/
#define STACK_FRAME_NON_STANDARD(func) \
- static void __used __section(__func_stack_frame_non_standard) \
+ static void __used __section(.discard.func_stack_frame_non_standard) \
*__func_stack_frame_non_standard_##func = func
#else /* !CONFIG_STACK_VALIDATION */
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 4dedd0d..30d752a 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -854,6 +854,7 @@ static const char *const section_white_list[] =
".cmem*", /* EZchip */
".fmt_slot*", /* EZchip */
".gnu.lto*",
+ ".discard.*",
NULL
};
diff --git a/scripts/module-common.lds b/scripts/module-common.lds
index 73a2c7d..cf7e52e 100644
--- a/scripts/module-common.lds
+++ b/scripts/module-common.lds
@@ -4,7 +4,10 @@
* combine them automatically.
*/
SECTIONS {
- /DISCARD/ : { *(.discard) }
+ /DISCARD/ : {
+ *(.discard)
+ *(.discard.*)
+ }
__ksymtab 0 : { *(SORT(___ksymtab+*)) }
__ksymtab_gpl 0 : { *(SORT(___ksymtab_gpl+*)) }
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 5fc52ee..bd12eb1 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -339,13 +339,14 @@ static int add_dead_ends(struct objtool_file *file)
struct instruction *insn;
bool found;
- sec = find_section_by_name(file->elf, ".rela__unreachable");
+ sec = find_section_by_name(file->elf, ".rela.discard.unreachable");
if (!sec)
return 0;
list_for_each_entry(rela, &sec->rela_list, list) {
if (rela->sym->type != STT_SECTION) {
- WARN("unexpected relocation symbol type in
.rela__unreachable");
+ WARN("unexpected relocation symbol type in %s",
+ sec->name);
return -1;
}
insn = find_insn(file, rela->sym->sec, rela->addend);
@@ -1272,7 +1273,7 @@ int cmd_check(int argc, const char **argv)
INIT_LIST_HEAD(&file.insn_list);
hash_init(file.insn_hash);
- file.whitelist = find_section_by_name(file.elf,
"__func_stack_frame_non_standard");
+ file.whitelist = find_section_by_name(file.elf,
".discard.func_stack_frame_non_standard");
file.rodata = find_section_by_name(file.elf, ".rodata");
file.ignore_unreachables = false;
file.c_file = find_section_by_name(file.elf, ".comment");
--
2.7.4
