From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com,
jpoimboe@redhat.com, andrew.cooper3@citrix.com
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
ndesaulniers@google.com, keescook@chromium.org,
samitolvanen@google.com, mark.rutland@arm.com,
alyssa.milburn@intel.com, mbenes@suse.cz, rostedt@goodmis.org,
mhiramat@kernel.org, alexei.starovoitov@gmail.com
Subject: [PATCH v3 37/39] objtool: Optionally WARN about unused ANNOTATE_NOENDBR
Date: Thu, 03 Mar 2022 12:23:58 +0100 [thread overview]
Message-ID: <20220303112827.210703687@infradead.org> (raw)
In-Reply-To: 20220303112321.422525803@infradead.org
Separate option because this option is somewhat prone to false
positives since a bunch of symbols/annotations are not correctly
#ifdef'ed, presumably to avoid clutter.
Can be manually ran on allmodconfig builds using OBJTOOL_ARGS.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
tools/objtool/builtin-check.c | 3 +-
tools/objtool/check.c | 45 +++++++++++++++++++++++++++++---
tools/objtool/include/objtool/builtin.h | 2 -
tools/objtool/include/objtool/check.h | 3 +-
4 files changed, 46 insertions(+), 7 deletions(-)
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -21,7 +21,7 @@
bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
lto, vmlinux, mcount, noinstr, backup, sls, dryrun,
- ibt;
+ ibt, ibt_warn;
static const char * const check_usage[] = {
"objtool check [<options>] file.o",
@@ -49,6 +49,7 @@ const struct option check_options[] = {
OPT_BOOLEAN('S', "sls", &sls, "validate straight-line-speculation"),
OPT_BOOLEAN(0, "dry-run", &dryrun, "don't write the modifications"),
OPT_BOOLEAN(0, "ibt", &ibt, "validate ENDBR placement"),
+ OPT_BOOLEAN(0, "ibt-warn", &ibt_warn, "warn about unused ANNOTATE_ENDBR"),
OPT_END(),
};
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1814,6 +1814,19 @@ static void set_func_state(struct cfi_st
state->stack_size = initial_func_cfi.cfa.offset;
}
+static bool insn_is_endbr(struct instruction *insn)
+{
+ if (insn->type == INSN_ENDBR)
+ return true;
+
+ if (insn->noendbr) {
+ insn->noendbr_hit = 1;
+ return true;
+ }
+
+ return false;
+}
+
static int read_unwind_hints(struct objtool_file *file)
{
struct cfi_state cfi = init_cfi;
@@ -1860,8 +1873,7 @@ static int read_unwind_hints(struct objt
if (ibt && hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
- if (sym && sym->bind == STB_GLOBAL &&
- insn->type != INSN_ENDBR && !insn->noendbr) {
+ if (sym && sym->bind == STB_GLOBAL && !insn_is_endbr(insn)) {
WARN_FUNC("UNWIND_HINT_IRET_REGS without ENDBR",
insn->sec, insn->offset);
}
@@ -3146,7 +3158,7 @@ static void validate_ibt_dest(struct obj
return;
}
- if (dest->noendbr)
+ if (insn_is_endbr(dest))
return;
warn_noendbr("", insn->sec, insn->offset, dest);
@@ -3687,7 +3699,7 @@ static int validate_ibt(struct objtool_f
struct instruction *dest;
dest = validate_ibt_reloc(file, reloc);
- if (is_data && dest && !dest->noendbr) {
+ if (is_data && dest && !insn_is_endbr(dest)) {
warn_noendbr("data ", reloc->sym->sec,
reloc->sym->offset + reloc->addend,
dest);
@@ -3695,6 +3707,31 @@ static int validate_ibt(struct objtool_f
}
}
+ if (ibt_warn) {
+ struct symbol *hypercall_page = find_symbol_by_name(file->elf, "hypercall_page");
+ struct instruction *insn;
+
+ for_each_insn(file, insn) {
+ if (!insn->noendbr || insn->noendbr_hit)
+ continue;
+
+ if (hypercall_page) {
+ /*
+ * The Xen hypercall page contains many
+ * hypercalls (and unused slots) that are never
+ * indirectly called. Still every slot has an
+ * annotation. Suppress complaints.
+ */
+ if (insn->sec == hypercall_page->sec &&
+ insn->offset >= hypercall_page->offset &&
+ insn->offset < hypercall_page->offset + hypercall_page->len)
+ continue;
+ }
+
+ WARN_FUNC("unused ANNOTATE_NOENDBR", insn->sec, insn->offset);
+ }
+ }
+
return 0;
}
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -10,7 +10,7 @@
extern const struct option check_options[];
extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats,
lto, vmlinux, mcount, noinstr, backup, sls, dryrun,
- ibt;
+ ibt, ibt_warn;
extern int cmd_parse_options(int argc, const char **argv, const char * const usage[]);
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -51,7 +51,8 @@ struct instruction {
ignore_alts : 1,
hint : 1,
retpoline_safe : 1,
- noendbr : 1;
+ noendbr : 1,
+ noendbr_hit : 1;
/* 2 bit hole */
s8 instr;
u8 visited;
next prev parent reply other threads:[~2022-03-03 11:33 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-03 11:23 [PATCH v3 00/39] x86: Kernel IBT Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 01/39] static_call: Avoid building empty .static_call_sites Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 02/39] x86/module: Fix the paravirt vs alternative order Peter Zijlstra
2022-03-08 13:58 ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 03/39] objtool: Add --dry-run Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 04/39] x86/ibt: Base IBT bits Peter Zijlstra
2022-03-07 11:17 ` Peter Zijlstra
2022-03-07 12:25 ` Joao Moreira
2022-03-07 18:19 ` Nick Desaulniers
2022-03-03 11:23 ` [PATCH v3 05/39] x86/ibt: Add ANNOTATE_NOENDBR Peter Zijlstra
2022-03-04 18:59 ` Josh Poimboeuf
2022-03-04 20:22 ` Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 06/39] x86/text-patching: Make text_gen_insn() play nice with ANNOTATE_NOENDBR Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 07/39] x86/ibt,paravirt: Use text_gen_insn() for paravirt_patch() Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 08/39] x86/entry: Cleanup PARAVIRT Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 09/39] x86/entry,xen: Early rewrite of restore_regs_and_return_to_kernel() Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 10/39] x86/ibt,xen: Sprinkle the ENDBR Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 11/39] x86/ibt,entry: Sprinkle ENDBR dust Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 12/39] x86/linkage: Add ENDBR to SYM_FUNC_START*() Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 13/39] x86/ibt,paravirt: Sprinkle ENDBR Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 14/39] x86/ibt,crypto: Add ENDBR for the jump-table entries Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 15/39] x86/ibt,kvm: Add ENDBR to fastops Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 16/39] x86/ibt,ftrace: Search for __fentry__ location Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 17/39] x86/livepatch: Validate " Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 18/39] x86/ibt,ftrace: Make function-graph play nice Peter Zijlstra
2022-03-04 17:51 ` Josh Poimboeuf
2022-03-04 19:48 ` Peter Zijlstra
2022-03-04 21:03 ` Josh Poimboeuf
2022-03-04 21:44 ` Peter Zijlstra
2022-03-04 22:05 ` Josh Poimboeuf
2022-03-04 23:08 ` David Laight
2022-03-03 11:23 ` [PATCH v3 19/39] x86/ibt,kprobes: Cure sym+0 equals fentry woes Peter Zijlstra
2022-03-07 9:44 ` Masami Hiramatsu
2022-03-03 11:23 ` [PATCH v3 20/39] x86/ibt,bpf: Add ENDBR instructions to prologue and trampoline Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 21/39] x86/ibt,ftrace: Add ENDBR to samples/ftrace Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 22/39] x86/ibt: Add IBT feature, MSR and #CP handling Peter Zijlstra
2022-03-04 17:57 ` Josh Poimboeuf
2022-03-04 20:38 ` Peter Zijlstra
2022-03-04 18:07 ` Josh Poimboeuf
2022-03-04 20:39 ` Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 23/39] x86/alternative: Simplify int3_selftest_ip Peter Zijlstra
2022-03-04 18:02 ` Josh Poimboeuf
2022-03-04 18:09 ` Josh Poimboeuf
2022-03-03 11:23 ` [PATCH v3 24/39] x86/ibt: Disable IBT around firmware Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 25/39] x86/bugs: Disable Retpoline when IBT Peter Zijlstra
2022-03-04 17:39 ` Josh Poimboeuf
2022-03-03 11:23 ` [PATCH v3 26/39] x86/ibt: Annotate text references Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 27/39] x86/ibt,ftrace: Annotate ftrace code patching Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 28/39] x86/ibt,sev: Annotations Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 29/39] x86/ibt: Dont generate ENDBR in .discard.text Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 30/39] x86/ibt: Ensure module init/exit points have references Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 31/39] objtool: Rename --duplicate to --lto Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 32/39] Kbuild: Allow whole module objtool runs Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 33/39] objtool: Read the NOENDBR annotation Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 34/39] objtool: Have WARN_FUNC fall back to sym+off Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 35/39] objtool: Add IBT/ENDBR decoding Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 36/39] objtool: Validate IBT assumptions Peter Zijlstra
2022-03-03 11:23 ` Peter Zijlstra [this message]
2022-03-04 18:27 ` [PATCH v3 37/39] objtool: Optionally WARN about unused ANNOTATE_NOENDBR Josh Poimboeuf
2022-03-03 11:23 ` [PATCH v3 38/39] objtool: Find unused ENDBR instructions Peter Zijlstra
2022-03-03 11:24 ` [PATCH v3 39/39] x86/alternative: Use .ibt_endbr_seal to seal indirect calls Peter Zijlstra
2022-03-04 19:09 ` [PATCH v3 00/39] x86: Kernel IBT Josh Poimboeuf
2022-03-04 20:22 ` Peter Zijlstra
2022-03-04 21:39 ` Peter Zijlstra
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