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Message-Id: <dcd3ceffd15a54822c6183e5766d21ad06082b45.1650300597.git.jpoimboe@redhat.com>
Date: Mon, 18 Apr 2022 09:50:43 -0700
From: Josh Poimboeuf <jpoimboe@...hat.com>
To: x86@...nel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
linux-kernel@...r.kernel.org, Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH v2 24/25] objtool: Remove --lto and --vmlinux in favor of --link
The '--lto' option is a confusing way of telling objtool to do stack
validation despite it being a linked object. It's no longer needed now
that an explicit '--stackval' option exists. The '--vmlinux' option is
also redundant.
Remove both options in favor of a straightforward '--link' option which
identifies a linked object.
Also, implicitly set '--link' with a warning if the user forgets to do
so and we can tell that it's a linked object. This makes it easier for
manual vmlinux runs.
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
scripts/Makefile.build | 4 ++-
scripts/link-vmlinux.sh | 8 ++---
tools/objtool/builtin-check.c | 39 +++++++++++++++++++++---
tools/objtool/check.c | 40 +++++++++----------------
tools/objtool/elf.c | 3 ++
tools/objtool/include/objtool/builtin.h | 3 +-
tools/objtool/include/objtool/elf.h | 12 +++++++-
7 files changed, 70 insertions(+), 39 deletions(-)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 6c206a1bab97..ac8167227bc0 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -229,7 +229,7 @@ objtool := $(objtree)/tools/objtool/objtool
objtool_args = \
$(if $(CONFIG_HAVE_JUMP_LABEL_HACK), --hacks=jump_label) \
$(if $(CONFIG_HAVE_NOINSTR_HACK), --hacks=noinstr) \
- $(if $(CONFIG_X86_KERNEL_IBT), --lto --ibt) \
+ $(if $(CONFIG_X86_KERNEL_IBT), --ibt) \
$(if $(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL), --mcount) \
$(if $(CONFIG_UNWINDER_ORC), --orc) \
$(if $(CONFIG_RETPOLINE), --retpoline) \
@@ -237,6 +237,7 @@ objtool_args = \
$(if $(CONFIG_STACK_VALIDATION), --stackval) \
$(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call) \
$(if $(CONFIG_X86_SMAP), --uaccess) \
+ $(if $(linked-object), --link) \
$(if $(part-of-module), --module) \
$(if $(CONFIG_GCOV_KERNEL), --no-unreachable)
@@ -306,6 +307,7 @@ quiet_cmd_cc_prelink_modules = LD [M] $@
# modules into native code
$(obj)/%.prelink.o: objtool-enabled = y
$(obj)/%.prelink.o: part-of-module := y
+$(obj)/%.prelink.o: linked-object := y
$(obj)/%.prelink.o: $(obj)/%.o FORCE
$(call if_changed,cc_prelink_modules)
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index fce4f41816cd..eb9324f07f3d 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -114,8 +114,8 @@ objtool_link()
if is_enabled CONFIG_LTO_CLANG || is_enabled CONFIG_X86_KERNEL_IBT; then
- # Don't perform vmlinux validation unless explicitly requested,
- # but run objtool on vmlinux.o now that we have an object file.
+ # For LTO and IBT, objtool doesn't run on individual
+ # translation units. Run everything on vmlinux instead.
if is_enabled CONFIG_HAVE_JUMP_LABEL_HACK; then
objtoolopt="${objtoolopt} --hacks=jump_label"
@@ -156,8 +156,6 @@ objtool_link()
if is_enabled CONFIG_X86_SMAP; then
objtoolopt="${objtoolopt} --uaccess"
fi
-
- objtoolopt="${objtoolopt} --lto"
fi
if is_enabled CONFIG_NOINSTR_VALIDATION; then
@@ -170,7 +168,7 @@ objtool_link()
objtoolopt="${objtoolopt} --no-unreachable"
fi
- objtoolopt="${objtoolopt} --vmlinux"
+ objtoolopt="${objtoolopt} --link"
info OBJTOOL ${1}
tools/objtool/objtool ${objtoolopt} ${1}
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 1803a63147e4..f4c3a5091737 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -9,6 +9,11 @@
#include <objtool/builtin.h>
#include <objtool/objtool.h>
+#define ERROR(format, ...) \
+ fprintf(stderr, \
+ "error: objtool: " format "\n", \
+ ##__VA_ARGS__)
+
struct opts opts;
static const char * const check_usage[] = {
@@ -73,12 +78,11 @@ const struct option check_options[] = {
OPT_BOOLEAN(0, "backtrace", &opts.backtrace, "unwind on error"),
OPT_BOOLEAN(0, "backup", &opts.backup, "create .orig files before modification"),
OPT_BOOLEAN(0, "dry-run", &opts.dryrun, "don't write modifications"),
- OPT_BOOLEAN(0, "lto", &opts.lto, "whole-archive like runs"),
+ OPT_BOOLEAN(0, "link", &opts.link, "object is a linked object"),
OPT_BOOLEAN(0, "module", &opts.module, "object is part of a kernel module"),
OPT_BOOLEAN(0, "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),
OPT_BOOLEAN(0, "sec-address", &opts.sec_address, "print section addresses in warnings"),
OPT_BOOLEAN(0, "stats", &opts.stats, "print statistics"),
- OPT_BOOLEAN(0, "vmlinux", &opts.vmlinux, "vmlinux.o validation"),
OPT_END(),
};
@@ -124,7 +128,7 @@ static bool opts_valid(void)
opts.static_call ||
opts.uaccess) {
if (opts.dump_orc) {
- fprintf(stderr, "--dump can't be combined with other options\n");
+ ERROR("--dump can't be combined with other options");
return false;
}
@@ -134,10 +138,34 @@ static bool opts_valid(void)
if (opts.dump_orc)
return true;
- fprintf(stderr, "At least one command required\n");
+ ERROR("At least one command required");
return false;
}
+static bool link_opts_valid(struct objtool_file *file)
+{
+ if (opts.link)
+ return true;
+
+ if (has_multiple_files(file->elf)) {
+ ERROR("Linked object detected, forcing --link");
+ opts.link = true;
+ return true;
+ }
+
+ if (opts.noinstr) {
+ ERROR("--noinstr requires --link");
+ return false;
+ }
+
+ if (opts.ibt) {
+ ERROR("--ibt requires --link");
+ return false;
+ }
+
+ return true;
+}
+
int objtool_run(int argc, const char **argv)
{
const char *objname;
@@ -157,6 +185,9 @@ int objtool_run(int argc, const char **argv)
if (!file)
return 1;
+ if (!link_opts_valid(file))
+ return 1;
+
ret = check(file);
if (ret)
return ret;
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 6a7b5fa3fe1b..60b6a2a712b5 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -264,7 +264,8 @@ static void init_cfi_state(struct cfi_state *cfi)
cfi->drap_offset = -1;
}
-static void init_insn_state(struct insn_state *state, struct section *sec)
+static void init_insn_state(struct objtool_file *file, struct insn_state *state,
+ struct section *sec)
{
memset(state, 0, sizeof(*state));
init_cfi_state(&state->cfi);
@@ -274,7 +275,7 @@ static void init_insn_state(struct insn_state *state, struct section *sec)
* not correctly determine insn->call_dest->sec (external symbols do
* not have a section).
*/
- if (opts.vmlinux && opts.noinstr && sec)
+ if (opts.link && opts.noinstr && sec)
state->noinstr = sec->noinstr;
}
@@ -3406,7 +3407,7 @@ static int validate_unwind_hints(struct objtool_file *file, struct section *sec)
if (!file->hints)
return 0;
- init_insn_state(&state, sec);
+ init_insn_state(file, &state, sec);
if (sec) {
insn = find_insn(file, sec, 0);
@@ -3492,14 +3493,14 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
return true;
/*
- * Whole archive runs might encounder dead code from weak symbols.
+ * Whole archive runs might encounter dead code from weak symbols.
* This is where the linker will have dropped the weak symbol in
* favour of a regular symbol, but leaves the code in place.
*
* In this case we'll find a piece of code (whole function) that is not
* covered by a !section symbol. Ignore them.
*/
- if (!insn->func && opts.lto) {
+ if (opts.link && !insn->func) {
int size = find_symbol_hole_containing(insn->sec, insn->offset);
unsigned long end = insn->offset + size;
@@ -3621,7 +3622,7 @@ static int validate_section(struct objtool_file *file, struct section *sec)
if (func->type != STT_FUNC)
continue;
- init_insn_state(&state, sec);
+ init_insn_state(file, &state, sec);
set_func_state(&state.cfi);
warnings += validate_symbol(file, sec, func, &state);
@@ -3630,7 +3631,7 @@ static int validate_section(struct objtool_file *file, struct section *sec)
return warnings;
}
-static int validate_vmlinux_functions(struct objtool_file *file)
+static int validate_noinstr_sections(struct objtool_file *file)
{
struct section *sec;
int warnings = 0;
@@ -3891,16 +3892,6 @@ int check(struct objtool_file *file)
{
int ret, warnings = 0;
- if (opts.lto && !(opts.vmlinux || opts.module)) {
- fprintf(stderr, "--lto requires: --vmlinux or --module\n");
- return 1;
- }
-
- if (opts.ibt && !opts.lto) {
- fprintf(stderr, "--ibt requires: --lto\n");
- return 1;
- }
-
arch_initial_func_cfi_state(&initial_func_cfi);
init_cfi_state(&init_cfi);
init_cfi_state(&func_cfi);
@@ -3921,15 +3912,6 @@ int check(struct objtool_file *file)
if (list_empty(&file->insn_list))
goto out;
- if (opts.vmlinux && !opts.lto) {
- ret = validate_vmlinux_functions(file);
- if (ret < 0)
- goto out;
-
- warnings += ret;
- goto out;
- }
-
if (opts.retpoline) {
ret = validate_retpoline(file);
if (ret < 0)
@@ -3954,6 +3936,12 @@ int check(struct objtool_file *file)
goto out;
warnings += ret;
}
+
+ } else if (opts.noinstr) {
+ ret = validate_noinstr_sections(file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
}
if (opts.ibt) {
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index f7b2ad27bb1c..41fea838aeba 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -377,6 +377,9 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
sym->type = GELF_ST_TYPE(sym->sym.st_info);
sym->bind = GELF_ST_BIND(sym->sym.st_info);
+ if (sym->type == STT_FILE)
+ elf->num_files++;
+
sym->offset = sym->sym.st_value;
sym->len = sym->sym.st_size;
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index f3a1a754b5c4..280ea18b7f2b 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -28,12 +28,11 @@ struct opts {
bool backtrace;
bool backup;
bool dryrun;
- bool lto;
+ bool link;
bool module;
bool no_unreachable;
bool sec_address;
bool stats;
- bool vmlinux;
};
extern struct opts opts;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 22ba7e2b816e..9bb1e20c4462 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -86,7 +86,7 @@ struct elf {
int fd;
bool changed;
char *name;
- unsigned int text_size;
+ unsigned int text_size, num_files;
struct list_head sections;
int symbol_bits;
@@ -131,6 +131,16 @@ static inline u32 reloc_hash(struct reloc *reloc)
return sec_offset_hash(reloc->sec, reloc->offset);
}
+/*
+ * Try to see if it's a whole archive (vmlinux.o or module).
+ *
+ * Note this will miss the case where a module only has one source file.
+ */
+static inline bool has_multiple_files(struct elf *elf)
+{
+ return elf->num_files > 1;
+}
+
struct elf *elf_open_read(const char *name, int flags);
struct section *elf_create_section(struct elf *elf, const char *name, unsigned int sh_flags, size_t entsize, int nr);
--
2.34.1
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