Increase the per-function WARN_FUNC() rate limit from 1 to 2. If the
number of warnings for a given function goes beyond 2, print "skipping
duplicate warning(s)". This helps root out additional warnings in a
function that might be hiding behind the first one.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
tools/objtool/check.c | 2 +-
tools/objtool/include/objtool/elf.h | 2 +-
tools/objtool/include/objtool/warn.h | 14 +++++++++++---
3 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 6b9ad3afe389..3ddaefe97f55 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4528,7 +4528,7 @@ static int disas_warned_funcs(struct objtool_file *file)
char *funcs = NULL, *tmp;
for_each_sym(file, sym) {
- if (sym->warned) {
+ if (sym->warnings) {
if (!funcs) {
funcs = malloc(strlen(sym->name) + 1);
strcpy(funcs, sym->name);
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index d7e815c2fd15..223ac1c24b90 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -65,10 +65,10 @@ struct symbol {
u8 return_thunk : 1;
u8 fentry : 1;
u8 profiling_func : 1;
- u8 warned : 1;
u8 embedded_insn : 1;
u8 local_label : 1;
u8 frame_pointer : 1;
+ u8 warnings : 2;
struct list_head pv_target;
struct reloc *relocs;
};
diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
index ac04d3fe4dd9..6180288927fd 100644
--- a/tools/objtool/include/objtool/warn.h
+++ b/tools/objtool/include/objtool/warn.h
@@ -53,14 +53,22 @@ static inline char *offstr(struct section *sec, unsigned long offset)
free(_str); \
})
+#define WARN_LIMIT 2
+
#define WARN_INSN(insn, format, ...) \
({ \
struct instruction *_insn = (insn); \
- if (!_insn->sym || !_insn->sym->warned) \
+ BUILD_BUG_ON(WARN_LIMIT > 2); \
+ if (!_insn->sym || _insn->sym->warnings < WARN_LIMIT) { \
WARN_FUNC(format, _insn->sec, _insn->offset, \
##__VA_ARGS__); \
- if (_insn->sym) \
- _insn->sym->warned = 1; \
+ if (_insn->sym) \
+ _insn->sym->warnings++; \
+ } else if (_insn->sym && _insn->sym->warnings == WARN_LIMIT) { \
+ WARN_FUNC("skipping duplicate warning(s)", \
+ _insn->sec, _insn->offset); \
+ _insn->sym->warnings++; \
+ } \
})
#define BT_INSN(insn, format, ...) \
--
2.48.1On Fri, Mar 14, 2025 at 12:29:03PM -0700, Josh Poimboeuf wrote:
> Increase the per-function WARN_FUNC() rate limit from 1 to 2. If the
> number of warnings for a given function goes beyond 2, print "skipping
> duplicate warning(s)". This helps root out additional warnings in a
> function that might be hiding behind the first one.
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
> tools/objtool/check.c | 2 +-
> tools/objtool/include/objtool/elf.h | 2 +-
> tools/objtool/include/objtool/warn.h | 14 +++++++++++---
> 3 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> index 6b9ad3afe389..3ddaefe97f55 100644
> --- a/tools/objtool/check.c
> +++ b/tools/objtool/check.c
> @@ -4528,7 +4528,7 @@ static int disas_warned_funcs(struct objtool_file *file)
> char *funcs = NULL, *tmp;
>
> for_each_sym(file, sym) {
> - if (sym->warned) {
> + if (sym->warnings) {
> if (!funcs) {
> funcs = malloc(strlen(sym->name) + 1);
> strcpy(funcs, sym->name);
> diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
> index d7e815c2fd15..223ac1c24b90 100644
> --- a/tools/objtool/include/objtool/elf.h
> +++ b/tools/objtool/include/objtool/elf.h
> @@ -65,10 +65,10 @@ struct symbol {
> u8 return_thunk : 1;
> u8 fentry : 1;
> u8 profiling_func : 1;
> - u8 warned : 1;
> u8 embedded_insn : 1;
> u8 local_label : 1;
> u8 frame_pointer : 1;
> + u8 warnings : 2;
> struct list_head pv_target;
> struct reloc *relocs;
> };
> diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
> index ac04d3fe4dd9..6180288927fd 100644
> --- a/tools/objtool/include/objtool/warn.h
> +++ b/tools/objtool/include/objtool/warn.h
> @@ -53,14 +53,22 @@ static inline char *offstr(struct section *sec, unsigned long offset)
> free(_str); \
> })
>
> +#define WARN_LIMIT 2
> +
> #define WARN_INSN(insn, format, ...) \
> ({ \
> struct instruction *_insn = (insn); \
> - if (!_insn->sym || !_insn->sym->warned) \
> + BUILD_BUG_ON(WARN_LIMIT > 2); \
Shouldn't this be >3? Anyway, I think it would be clearer if the
coupling was more explicit, e.g:
diff --git i/tools/objtool/include/objtool/elf.h w/tools/objtool/include/objtool/elf.h
index 223ac1c24b90..a86e43d2056f 100644
--- i/tools/objtool/include/objtool/elf.h
+++ w/tools/objtool/include/objtool/elf.h
@@ -46,6 +46,8 @@ struct section {
struct reloc *relocs;
};
+#define STRUCT_SYMBOL_WARNING_BITS 2
+
struct symbol {
struct list_head list;
struct rb_node node;
@@ -68,7 +70,7 @@ struct symbol {
u8 embedded_insn : 1;
u8 local_label : 1;
u8 frame_pointer : 1;
- u8 warnings : 2;
+ u8 warnings : STRUCT_SYMBOL_WARNING_BITS;
struct list_head pv_target;
struct reloc *relocs;
};
diff --git i/tools/objtool/include/objtool/warn.h w/tools/objtool/include/objtool/warn.h
index e72b9d630551..2fba6866fd2d 100644
--- i/tools/objtool/include/objtool/warn.h
+++ w/tools/objtool/include/objtool/warn.h
@@ -56,6 +56,7 @@ static inline char *offstr(struct section *sec, unsigned long offset)
})
#define WARN_LIMIT 2
+static_assert(WARN_LIMIT < (1 << STRUCT_SYMBOL_WARNING_BITS), "symbol.warnings too small");
#define WARN_INSN(insn, format, ...) \
({
Or just drop the bitfield (surely it can't be that important to save a
byte here?) and use sizeof, e.g:
BUILD_BUG_ON(ilog2(WARN_LIMIT) > sizeof(_insn->sym->warnings));
On Mon, 17 Mar 2025, Brendan Jackman wrote:
> On Fri, Mar 14, 2025 at 12:29:03PM -0700, Josh Poimboeuf wrote:
> > Increase the per-function WARN_FUNC() rate limit from 1 to 2. If the
> > number of warnings for a given function goes beyond 2, print "skipping
> > duplicate warning(s)". This helps root out additional warnings in a
> > function that might be hiding behind the first one.
> >
> > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> > ---
> > tools/objtool/check.c | 2 +-
> > tools/objtool/include/objtool/elf.h | 2 +-
> > tools/objtool/include/objtool/warn.h | 14 +++++++++++---
> > 3 files changed, 13 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/objtool/check.c b/tools/objtool/check.c
> > index 6b9ad3afe389..3ddaefe97f55 100644
> > --- a/tools/objtool/check.c
> > +++ b/tools/objtool/check.c
> > @@ -4528,7 +4528,7 @@ static int disas_warned_funcs(struct objtool_file *file)
> > char *funcs = NULL, *tmp;
> >
> > for_each_sym(file, sym) {
> > - if (sym->warned) {
> > + if (sym->warnings) {
> > if (!funcs) {
> > funcs = malloc(strlen(sym->name) + 1);
> > strcpy(funcs, sym->name);
> > diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
> > index d7e815c2fd15..223ac1c24b90 100644
> > --- a/tools/objtool/include/objtool/elf.h
> > +++ b/tools/objtool/include/objtool/elf.h
> > @@ -65,10 +65,10 @@ struct symbol {
> > u8 return_thunk : 1;
> > u8 fentry : 1;
> > u8 profiling_func : 1;
> > - u8 warned : 1;
> > u8 embedded_insn : 1;
> > u8 local_label : 1;
> > u8 frame_pointer : 1;
> > + u8 warnings : 2;
> > struct list_head pv_target;
> > struct reloc *relocs;
> > };
> > diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
> > index ac04d3fe4dd9..6180288927fd 100644
> > --- a/tools/objtool/include/objtool/warn.h
> > +++ b/tools/objtool/include/objtool/warn.h
> > @@ -53,14 +53,22 @@ static inline char *offstr(struct section *sec, unsigned long offset)
> > free(_str); \
> > })
> >
> > +#define WARN_LIMIT 2
> > +
> > #define WARN_INSN(insn, format, ...) \
> > ({ \
> > struct instruction *_insn = (insn); \
> > - if (!_insn->sym || !_insn->sym->warned) \
> > + BUILD_BUG_ON(WARN_LIMIT > 2); \
>
> Shouldn't this be >3? Anyway, I think it would be clearer if the
> coupling was more explicit, e.g:
I think it is correct but I also think that the difference between bits
and the actual number of "allowed" warnings can be confusing.
> diff --git i/tools/objtool/include/objtool/elf.h w/tools/objtool/include/objtool/elf.h
> index 223ac1c24b90..a86e43d2056f 100644
> --- i/tools/objtool/include/objtool/elf.h
> +++ w/tools/objtool/include/objtool/elf.h
> @@ -46,6 +46,8 @@ struct section {
> struct reloc *relocs;
> };
>
> +#define STRUCT_SYMBOL_WARNING_BITS 2
> +
> struct symbol {
> struct list_head list;
> struct rb_node node;
> @@ -68,7 +70,7 @@ struct symbol {
> u8 embedded_insn : 1;
> u8 local_label : 1;
> u8 frame_pointer : 1;
> - u8 warnings : 2;
> + u8 warnings : STRUCT_SYMBOL_WARNING_BITS;
> struct list_head pv_target;
> struct reloc *relocs;
> };
> diff --git i/tools/objtool/include/objtool/warn.h w/tools/objtool/include/objtool/warn.h
> index e72b9d630551..2fba6866fd2d 100644
> --- i/tools/objtool/include/objtool/warn.h
> +++ w/tools/objtool/include/objtool/warn.h
> @@ -56,6 +56,7 @@ static inline char *offstr(struct section *sec, unsigned long offset)
> })
>
> #define WARN_LIMIT 2
> +static_assert(WARN_LIMIT < (1 << STRUCT_SYMBOL_WARNING_BITS), "symbol.warnings too small");
>
> #define WARN_INSN(insn, format, ...) \
> ({
>
>
> Or just drop the bitfield (surely it can't be that important to save a
> byte here?) and use sizeof, e.g:
If I remember correctly, it is important. Josh and Peter spent quite some
time on optimizing the data structures in the past as every bit counts.
> BUILD_BUG_ON(ilog2(WARN_LIMIT) > sizeof(_insn->sym->warnings));
Miroslav
On Mon Mar 17, 2025 at 12:29 PM UTC, Miroslav Benes wrote:
> > > diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
> > > index ac04d3fe4dd9..6180288927fd 100644
> > > --- a/tools/objtool/include/objtool/warn.h
> > > +++ b/tools/objtool/include/objtool/warn.h
> > > @@ -53,14 +53,22 @@ static inline char *offstr(struct section *sec, unsigned long offset)
> > > free(_str); \
> > > })
> > >
> > > +#define WARN_LIMIT 2
> > > +
> > > #define WARN_INSN(insn, format, ...) \
> > > ({ \
> > > struct instruction *_insn = (insn); \
> > > - if (!_insn->sym || !_insn->sym->warned) \
> > > + BUILD_BUG_ON(WARN_LIMIT > 2); \
> >
> > Shouldn't this be >3? Anyway, I think it would be clearer if the
> > coupling was more explicit, e.g:
>
> I think it is correct but I also think that the difference between bits
> and the actual number of "allowed" warnings can be confusing.
Oh, yeah sorry I did not read this properly. So it's using
(1<<nbits)-2 as the "report that we're skipping duplicates" special
value.
So IMO we need something like:
/* Subtract one because the warnings==WARN_LIMIT is used to report skipped warnings. */
static_assert(WARN_LIMIT < (1 << STRUCT_SYMBOL_WARNING_BITS) - 1, "symbol.warnings too small");
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