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Date: Wed, 12 Apr 2023 12:03:20 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: linux-kernel@...r.kernel.org,
Peter Zijlstra <peterz@...radead.org>,
Miroslav Benes <mbenes@...e.cz>
Subject: [PATCH v2 5/9] objtool: Add verbose option for disassembling affected functions
When a warning is associated with a function, add an option to
disassemble that function.
This makes it easier for reporters to submit the information needed to
diagnose objtool warnings.
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
tools/objtool/Documentation/objtool.txt | 5 ++
tools/objtool/builtin-check.c | 5 ++
tools/objtool/check.c | 77 +++++++++++++++++++++++++
tools/objtool/include/objtool/builtin.h | 1 +
4 files changed, 88 insertions(+)
diff --git a/tools/objtool/Documentation/objtool.txt b/tools/objtool/Documentation/objtool.txt
index 8e53fc6735ef..4d6c5acde7a3 100644
--- a/tools/objtool/Documentation/objtool.txt
+++ b/tools/objtool/Documentation/objtool.txt
@@ -244,6 +244,11 @@ To achieve the validation, objtool enforces the following rules:
Objtool warnings
----------------
+NOTE: When requesting help with an objtool warning, please recreate with
+OBJTOOL_VERBOSE=1 (e.g., "make OBJTOOL_VERBOSE=1") and send the full
+output, including any disassembly below the warning, to the objtool
+maintainers.
+
For asm files, if you're getting an error which doesn't make sense,
first make sure that the affected code follows the above rules.
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 7c175198d09f..5e21cfb7661d 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -93,6 +93,7 @@ static const struct option check_options[] = {
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('v', "verbose", &opts.verbose, "verbose warnings"),
OPT_END(),
};
@@ -118,6 +119,10 @@ int cmd_parse_options(int argc, const char **argv, const char * const usage[])
parse_options(envc, envv, check_options, env_usage, 0);
}
+ env = getenv("OBJTOOL_VERBOSE");
+ if (env && !strcmp(env, "1"))
+ opts.verbose = true;
+
argc = parse_options(argc, argv, check_options, usage, 0);
if (argc != 1)
usage_with_options(usage, check_options);
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index d1d47baa252c..bc9dd69c9a45 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4509,6 +4509,81 @@ static int validate_reachable_instructions(struct objtool_file *file)
return warnings;
}
+/* 'funcs' is a space-separated list of function names */
+static int disas_funcs(const char *funcs)
+{
+ const char *objdump_str, *cross_compile;
+ int size, ret;
+ char *cmd;
+
+ cross_compile = getenv("CROSS_COMPILE");
+
+ objdump_str = "%sobjdump -wdr %s | gawk -M -v _funcs='%s' '"
+ "BEGIN { split(_funcs, funcs); }"
+ "/^$/ { func_match = 0; }"
+ "/<.*>:/ { "
+ "f = gensub(/.*<(.*)>:/, \"\\\\1\", 1);"
+ "for (i in funcs) {"
+ "if (funcs[i] == f) {"
+ "func_match = 1;"
+ "base = strtonum(\"0x\" $1);"
+ "break;"
+ "}"
+ "}"
+ "}"
+ "{"
+ "if (func_match) {"
+ "addr = strtonum(\"0x\" $1);"
+ "printf(\"%%04x \", addr - base);"
+ "print;"
+ "}"
+ "}' 1>&2";
+
+ /* fake snprintf() to calculate the size */
+ size = snprintf(NULL, 0, objdump_str, cross_compile, objname, funcs) + 1;
+ if (size <= 0) {
+ WARN("objdump string size calculation failed");
+ return -1;
+ }
+
+ cmd = malloc(size);
+
+ /* real snprintf() */
+ snprintf(cmd, size, objdump_str, cross_compile, objname, funcs);
+ ret = system(cmd);
+ if (ret) {
+ WARN("disassembly failed: %d", ret);
+ return -1;
+ }
+
+ return 0;
+}
+
+static int disas_warned_funcs(struct objtool_file *file)
+{
+ struct symbol *sym;
+ char *funcs = NULL, *tmp;
+
+ for_each_sym(file, sym) {
+ if (sym->warned) {
+ if (!funcs) {
+ funcs = malloc(strlen(sym->name) + 1);
+ strcpy(funcs, sym->name);
+ } else {
+ tmp = malloc(strlen(funcs) + strlen(sym->name) + 2);
+ sprintf(tmp, "%s %s", funcs, sym->name);
+ free(funcs);
+ funcs = tmp;
+ }
+ }
+ }
+
+ if (funcs)
+ disas_funcs(funcs);
+
+ return 0;
+}
+
int check(struct objtool_file *file)
{
int ret, warnings = 0;
@@ -4646,6 +4721,8 @@ int check(struct objtool_file *file)
warnings += ret;
}
+ if (opts.verbose)
+ disas_warned_funcs(file);
if (opts.stats) {
printf("nr_insns_visited: %ld\n", nr_insns_visited);
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 2a108e648b7a..fcca6662c8b4 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -37,6 +37,7 @@ struct opts {
bool no_unreachable;
bool sec_address;
bool stats;
+ bool verbose;
};
extern struct opts opts;
--
2.39.2
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