On 02/06/17 01:30, Ramsay Jones wrote:
>
>
> On 01/06/17 21:27, Luc Van Oostenryck wrote:
>> By default, sparse will warn if memcpy() (or memset(),
>> copy_from_user(), copy_to_user()) is called with a very large
>> static byte-count.
>>
>> But the limit is currently fixed at 100000, which may be fine
>> for some uses but not for others. For example, this value is
>> too low for sparse to be used on the git tree where, for example,
>> some array used to sort the index is cleared with memset().
>>
>> Change this by making the limit configurable via a new flag:
>> -fmemcpy-max-count.
>>
>> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
>> ---
>> lib.c | 16 ++++++++++++++++
>> lib.h | 1 +
>> sparse.1 | 10 ++++++++++
>> sparse.c | 3 +--
>> 4 files changed, 28 insertions(+), 2 deletions(-)
>>
>> diff --git a/lib.c b/lib.c
>> index 90fd2b494..1378cc243 100644
>> --- a/lib.c
>> +++ b/lib.c
>> @@ -256,6 +256,7 @@ int dbg_dead = 0;
>>
>> int fmem_report = 0;
>> int fdump_linearize;
>> +unsigned long fmemcpy_max_count = 100000;
>>
>> int preprocess_only;
>>
>> @@ -670,6 +671,19 @@ static char **handle_switch_O(char *arg, char **next)
>> return next;
>> }
>>
>> +static char **handle_switch_fmemcpy_max_count(char *arg, char **next)
>> +{
>> + unsigned long val;
>> + char *end;
>> +
>> + val = strtoul(arg, &end, 0);
>> + if (*end != '\0' || end == arg)
>> + die("error: missing argument to \"-fmemcpy-max-count=\"");
>> +
>> + fmemcpy_max_count = val;
>> + return next;
>> +}
>> +
>> static char **handle_switch_ftabstop(char *arg, char **next)
>> {
>> char *end;
>> @@ -713,6 +727,8 @@ static char **handle_switch_f(char *arg, char **next)
>> return handle_switch_ftabstop(arg+8, next);
>> if (!strncmp(arg, "dump-", 5))
>> return handle_switch_fdump(arg+5, next);
>> + if (!strncmp(arg, "memcpy-max-count=", 17))
>> + return handle_switch_fmemcpy_max_count(arg+17, next);
>>
>> /* handle switches w/ arguments above, boolean and only boolean below */
>> if (handle_simple_switch(arg, "mem-report", &fmem_report))
>> diff --git a/lib.h b/lib.h
>> index 8090fe247..b7cb451e0 100644
>> --- a/lib.h
>> +++ b/lib.h
>> @@ -143,6 +143,7 @@ extern int dbg_dead;
>>
>> extern int fmem_report;
>> extern int fdump_linearize;
>> +extern unsigned long fmemcpy_max_count;
>>
>> extern int arch_m64;
>>
>> diff --git a/sparse.1 b/sparse.1
>> index efbd78d01..932ac82ef 100644
>> --- a/sparse.1
>> +++ b/sparse.1
>> @@ -216,6 +216,9 @@ Warn about call of \fBmemset()\fR, \fBmemset()\fR, \fBcopy_from_user()\fR, or
>>
>> Sparse issues these warnings by default. To turn them off, use
>> \fB\-Wno\-memcpy\-max\-count\fR.
>> +
>> +The limit can be changed with \fB\-fmemcpy\-max\-count=COUNT\fR,
>> +the default being \fB100000\fR.
>> .
>> .TP
>> .B \-Wnon\-pointer\-null
>> @@ -364,6 +367,13 @@ Report some statistics about memory allocation used by the tool.
>> .
>> .SH OTHER OPTIONS
>> .TP
>> +.B \-fmemcpy-limit=COUNT
>> +By default, sparse will warn if \fBmemcpy()\fR (or \fBmemset()\fR,
>> +\fBcopy_from_user()\fR, copy_to_user()\fR) is called with a very large
>> +(known at compile-time) byte-count. COUNT is the value under which
>> +no such warning will be given. The default limit is 100000.
>> +.
>> +.TP
>
> So, in addition to -Wno-memcpy-max-count, you could turn the warning
> off with just -fmemcpy-limit=0. cool.
heh, so I obviously didn't read the code! Ahem. :-D
Thanks again.
ATB,
Ramsay Jones
>> .B \-ftabstop=WIDTH
>> Set the distance between tab stops. This helps sparse report correct
>> column numbers in warnings or errors. If the value is less than 1 or
>> diff --git a/sparse.c b/sparse.c
>> index aa5979f1a..bceacd94e 100644
>> --- a/sparse.c
>> +++ b/sparse.c
>> @@ -153,8 +153,7 @@ static void check_byte_count(struct instruction *insn, pseudo_t count)
>> return;
>> if (count->type == PSEUDO_VAL) {
>> unsigned long long val = count->value;
>> - if (Wmemcpy_max_count && val > 100000ULL)
>> -
>> + if (Wmemcpy_max_count && val > fmemcpy_max_count)
>> warning(insn->pos, "%s with byte count of %llu",
>> show_ident(insn->func->sym->ident), val);
>> return;
>>
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