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Subject[tip:core/objtool] objtool: Only print one warning per function
Commit-ID:  1bcb58a099938c33acda78b212ed67b06b3359ef
Gitweb: http://git.kernel.org/tip/1bcb58a099938c33acda78b212ed67b06b3359ef
Author: Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Wed, 9 Mar 2016 00:07:01 -0600
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 9 Mar 2016 10:48:10 +0100

objtool: Only print one warning per function

When objtool discovers an issue, it's very common for it to flood the
terminal with a lot of duplicate warnings. For example:

warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch
warning: objtool: rtlwifi_rate_mapping()+0x2f3: frame pointer state mismatch
warning: objtool: rtlwifi_rate_mapping()+0x2ff: frame pointer state mismatch
warning: objtool: rtlwifi_rate_mapping()+0x30b: frame pointer state mismatch
...

The first warning is usually all you need. Change it to only warn once
per function.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Bernd Petrovitsch <bernd@petrovitsch.priv.at>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris J Arges <chris.j.arges@canonical.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Pedro Alves <palves@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/c47f3ca38aa01e2a9b6601f9e38efd414c3f3c18.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
tools/objtool/builtin-check.c | 48 ++++++++++++++++++++++---------------------
1 file changed, 25 insertions(+), 23 deletions(-)

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index bfeee22..7515cb2 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -800,7 +800,7 @@ static int validate_branch(struct objtool_file *file,
struct instruction *insn;
struct section *sec;
unsigned char state;
- int ret, warnings = 0;
+ int ret;

insn = first;
sec = insn->sec;
@@ -809,7 +809,7 @@ static int validate_branch(struct objtool_file *file,
if (insn->alt_group && list_empty(&insn->alts)) {
WARN_FUNC("don't know how to handle branch to middle of alternative instruction group",
sec, insn->offset);
- warnings++;
+ return 1;
}

while (1) {
@@ -817,10 +817,10 @@ static int validate_branch(struct objtool_file *file,
if (frame_state(insn->state) != frame_state(state)) {
WARN_FUNC("frame pointer state mismatch",
sec, insn->offset);
- warnings++;
+ return 1;
}

- return warnings;
+ return 0;
}

/*
@@ -828,14 +828,15 @@ static int validate_branch(struct objtool_file *file,
* the next function.
*/
if (is_fentry_call(insn) && (state & STATE_FENTRY))
- return warnings;
+ return 0;

insn->visited = true;
insn->state = state;

list_for_each_entry(alt, &insn->alts, list) {
ret = validate_branch(file, alt->insn, state);
- warnings += ret;
+ if (ret)
+ return 1;
}

switch (insn->type) {
@@ -845,7 +846,7 @@ static int validate_branch(struct objtool_file *file,
if (state & STATE_FP_SAVED) {
WARN_FUNC("duplicate frame pointer save",
sec, insn->offset);
- warnings++;
+ return 1;
}
state |= STATE_FP_SAVED;
}
@@ -856,7 +857,7 @@ static int validate_branch(struct objtool_file *file,
if (state & STATE_FP_SETUP) {
WARN_FUNC("duplicate frame pointer setup",
sec, insn->offset);
- warnings++;
+ return 1;
}
state |= STATE_FP_SETUP;
}
@@ -875,9 +876,9 @@ static int validate_branch(struct objtool_file *file,
if (!nofp && has_modified_stack_frame(insn)) {
WARN_FUNC("return without frame pointer restore",
sec, insn->offset);
- warnings++;
+ return 1;
}
- return warnings;
+ return 0;

case INSN_CALL:
if (is_fentry_call(insn)) {
@@ -887,16 +888,16 @@ static int validate_branch(struct objtool_file *file,

ret = dead_end_function(file, insn->call_dest);
if (ret == 1)
- return warnings;
+ return 0;
if (ret == -1)
- warnings++;
+ return 1;

/* fallthrough */
case INSN_CALL_DYNAMIC:
if (!nofp && !has_valid_stack_frame(insn)) {
WARN_FUNC("call without frame pointer save/setup",
sec, insn->offset);
- warnings++;
+ return 1;
}
break;

@@ -905,15 +906,16 @@ static int validate_branch(struct objtool_file *file,
if (insn->jump_dest) {
ret = validate_branch(file, insn->jump_dest,
state);
- warnings += ret;
+ if (ret)
+ return 1;
} else if (has_modified_stack_frame(insn)) {
WARN_FUNC("sibling call from callable instruction with changed frame pointer",
sec, insn->offset);
- warnings++;
+ return 1;
} /* else it's a sibling call */

if (insn->type == INSN_JUMP_UNCONDITIONAL)
- return warnings;
+ return 0;

break;

@@ -922,13 +924,13 @@ static int validate_branch(struct objtool_file *file,
has_modified_stack_frame(insn)) {
WARN_FUNC("sibling call from callable instruction with changed frame pointer",
sec, insn->offset);
- warnings++;
+ return 1;
}

- return warnings;
+ return 0;

case INSN_BUG:
- return warnings;
+ return 0;

default:
break;
@@ -937,12 +939,11 @@ static int validate_branch(struct objtool_file *file,
insn = next_insn_same_sec(file, insn);
if (!insn) {
WARN("%s: unexpected end of section", sec->name);
- warnings++;
- return warnings;
+ return 1;
}
}

- return warnings;
+ return 0;
}

static bool is_gcov_insn(struct instruction *insn)
@@ -1055,7 +1056,8 @@ static int validate_functions(struct objtool_file *file)
if (insn->visited)
continue;

- if (!ignore_unreachable_insn(func, insn)) {
+ if (!ignore_unreachable_insn(func, insn) &&
+ !warnings) {
WARN_FUNC("function has unreachable instruction", insn->sec, insn->offset);
warnings++;
}
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