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.
Thanks!
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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