| Message ID | 20180308132225.13229-1-steve@sk2.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Mar 8, 2018 at 5:22 AM, Stephen Kitt <steve@sk2.org> wrote: > In preparation to enabling -Wvla, remove VLAs and replace them with > fixed-length arrays instead. > > The arrays fixed here, using the number of constant sections, aren't > really VLAs, but they appear so to the compiler. Since we know at > build-time how many critical sections there are, we might as well use > a pre-processor-level constant instead. > > This was prompted by https://lkml.org/lkml/2018/3/7/621 > > Signed-off-by: Stephen Kitt <steve@sk2.org> > --- > drivers/scsi/aic7xxx/aic79xx_core.c | 8 ++++---- > drivers/scsi/aic7xxx/aic79xx_seq.h_shipped | 3 +-- > drivers/scsi/aic7xxx/aic7xxx_core.c | 8 ++++---- > drivers/scsi/aic7xxx/aic7xxx_seq.h_shipped | 3 +-- > drivers/scsi/aic7xxx/aicasm/aicasm.c | 6 ++++-- > 5 files changed, 14 insertions(+), 14 deletions(-) > > diff --git a/drivers/scsi/aic7xxx/aic79xx_core.c b/drivers/scsi/aic7xxx/aic79xx_core.c > index b560f396ee99..034f4eebb160 100644 > --- a/drivers/scsi/aic7xxx/aic79xx_core.c > +++ b/drivers/scsi/aic7xxx/aic79xx_core.c > @@ -9338,9 +9338,9 @@ ahd_dumpseq(struct ahd_softc* ahd) > static void > ahd_loadseq(struct ahd_softc *ahd) > { > - struct cs cs_table[num_critical_sections]; > - u_int begin_set[num_critical_sections]; > - u_int end_set[num_critical_sections]; > + struct cs cs_table[NUM_CRITICAL_SECTIONS]; > + u_int begin_set[NUM_CRITICAL_SECTIONS]; > + u_int end_set[NUM_CRITICAL_SECTIONS]; > const struct patch *cur_patch; > u_int cs_count; > u_int cur_cs; > @@ -9456,7 +9456,7 @@ ahd_loadseq(struct ahd_softc *ahd) > * Move through the CS table until we find a CS > * that might apply to this instruction. > */ > - for (; cur_cs < num_critical_sections; cur_cs++) { > + for (; cur_cs < NUM_CRITICAL_SECTIONS; cur_cs++) { > if (critical_sections[cur_cs].end <= i) { > if (begin_set[cs_count] == TRUE > && end_set[cs_count] == FALSE) { > diff --git a/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped b/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped > index 4b51e232392f..20fb9ca9e271 100644 > --- a/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped > +++ b/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped > @@ -1186,5 +1186,4 @@ static const struct cs { > { 759, 763 } > }; > > -static const int num_critical_sections = sizeof(critical_sections) > - / sizeof(*critical_sections); > +#define NUM_CRITICAL_SECTIONS 14 The compiler doesn't treat "const" as a literal, hence the need to change this. However, you can still use the sizeof (actually, this is exactly ARRAY_SIZE()). Perhaps: #define NUM_CRITICAL_SECTIONS ARRAY_SIZE(critical_sections) ? Otherwise, looks great! -Kees
On Thu, 8 Mar 2018 11:52:25 -0800, Kees Cook <keescook@chromium.org> wrote: > On Thu, Mar 8, 2018 at 5:22 AM, Stephen Kitt <steve@sk2.org> wrote: > > -static const int num_critical_sections = sizeof(critical_sections) > > - / sizeof(*critical_sections); > > +#define NUM_CRITICAL_SECTIONS 14 > > The compiler doesn't treat "const" as a literal, hence the need to > change this. However, you can still use the sizeof (actually, this is > exactly ARRAY_SIZE()). Perhaps: > > #define NUM_CRITICAL_SECTIONS ARRAY_SIZE(critical_sections) > > ? > > Otherwise, looks great! Thanks, v2 incoming... Regards, Stephen
diff --git a/drivers/scsi/aic7xxx/aic79xx_core.c b/drivers/scsi/aic7xxx/aic79xx_core.c index b560f396ee99..034f4eebb160 100644 --- a/drivers/scsi/aic7xxx/aic79xx_core.c +++ b/drivers/scsi/aic7xxx/aic79xx_core.c @@ -9338,9 +9338,9 @@ ahd_dumpseq(struct ahd_softc* ahd) static void ahd_loadseq(struct ahd_softc *ahd) { - struct cs cs_table[num_critical_sections]; - u_int begin_set[num_critical_sections]; - u_int end_set[num_critical_sections]; + struct cs cs_table[NUM_CRITICAL_SECTIONS]; + u_int begin_set[NUM_CRITICAL_SECTIONS]; + u_int end_set[NUM_CRITICAL_SECTIONS]; const struct patch *cur_patch; u_int cs_count; u_int cur_cs; @@ -9456,7 +9456,7 @@ ahd_loadseq(struct ahd_softc *ahd) * Move through the CS table until we find a CS * that might apply to this instruction. */ - for (; cur_cs < num_critical_sections; cur_cs++) { + for (; cur_cs < NUM_CRITICAL_SECTIONS; cur_cs++) { if (critical_sections[cur_cs].end <= i) { if (begin_set[cs_count] == TRUE && end_set[cs_count] == FALSE) { diff --git a/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped b/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped index 4b51e232392f..20fb9ca9e271 100644 --- a/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped +++ b/drivers/scsi/aic7xxx/aic79xx_seq.h_shipped @@ -1186,5 +1186,4 @@ static const struct cs { { 759, 763 } }; -static const int num_critical_sections = sizeof(critical_sections) - / sizeof(*critical_sections); +#define NUM_CRITICAL_SECTIONS 14 diff --git a/drivers/scsi/aic7xxx/aic7xxx_core.c b/drivers/scsi/aic7xxx/aic7xxx_core.c index 6612ff3b2e83..e97eceacf522 100644 --- a/drivers/scsi/aic7xxx/aic7xxx_core.c +++ b/drivers/scsi/aic7xxx/aic7xxx_core.c @@ -6848,9 +6848,9 @@ ahc_dumpseq(struct ahc_softc* ahc) static int ahc_loadseq(struct ahc_softc *ahc) { - struct cs cs_table[num_critical_sections]; - u_int begin_set[num_critical_sections]; - u_int end_set[num_critical_sections]; + struct cs cs_table[NUM_CRITICAL_SECTIONS]; + u_int begin_set[NUM_CRITICAL_SECTIONS]; + u_int end_set[NUM_CRITICAL_SECTIONS]; const struct patch *cur_patch; u_int cs_count; u_int cur_cs; @@ -6915,7 +6915,7 @@ ahc_loadseq(struct ahc_softc *ahc) * Move through the CS table until we find a CS * that might apply to this instruction. */ - for (; cur_cs < num_critical_sections; cur_cs++) { + for (; cur_cs < NUM_CRITICAL_SECTIONS; cur_cs++) { if (critical_sections[cur_cs].end <= i) { if (begin_set[cs_count] == TRUE && end_set[cs_count] == FALSE) { diff --git a/drivers/scsi/aic7xxx/aic7xxx_seq.h_shipped b/drivers/scsi/aic7xxx/aic7xxx_seq.h_shipped index 07e93fbae706..d814f1d6b820 100644 --- a/drivers/scsi/aic7xxx/aic7xxx_seq.h_shipped +++ b/drivers/scsi/aic7xxx/aic7xxx_seq.h_shipped @@ -1304,5 +1304,4 @@ static const struct cs { { 875, 877 } }; -static const int num_critical_sections = sizeof(critical_sections) - / sizeof(*critical_sections); +#define NUM_CRITICAL_SECTIONS 7 diff --git a/drivers/scsi/aic7xxx/aicasm/aicasm.c b/drivers/scsi/aic7xxx/aicasm/aicasm.c index 21ac265280bf..bdffe84221ce 100644 --- a/drivers/scsi/aic7xxx/aicasm/aicasm.c +++ b/drivers/scsi/aic7xxx/aicasm/aicasm.c @@ -353,6 +353,7 @@ output_code() critical_section_t *cs; symbol_node_t *cur_node; int instrcount; + int num_critical_sections; instrcount = 0; fprintf(ofile, @@ -440,19 +441,20 @@ output_code() " uint16_t end;\n" "} critical_sections[] = {\n"); + num_critical_sections = 0; for (cs = TAILQ_FIRST(&cs_tailq); cs != NULL; cs = TAILQ_NEXT(cs, links)) { fprintf(ofile, "%s\t{ %d, %d }", cs == TAILQ_FIRST(&cs_tailq) ? "" : ",\n", cs->begin_addr, cs->end_addr); + num_critical_sections++; } fprintf(ofile, "\n};\n\n"); fprintf(ofile, -"static const int num_critical_sections = sizeof(critical_sections)\n" -" / sizeof(*critical_sections);\n"); + "#define NUM_CRITICAL_SECTIONS %d\n", num_critical_sections); fprintf(stderr, "%s: %d instructions used\n", appname, instrcount); }
In preparation to enabling -Wvla, remove VLAs and replace them with fixed-length arrays instead. The arrays fixed here, using the number of constant sections, aren't really VLAs, but they appear so to the compiler. Since we know at build-time how many critical sections there are, we might as well use a pre-processor-level constant instead. This was prompted by https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Stephen Kitt <steve@sk2.org> --- drivers/scsi/aic7xxx/aic79xx_core.c | 8 ++++---- drivers/scsi/aic7xxx/aic79xx_seq.h_shipped | 3 +-- drivers/scsi/aic7xxx/aic7xxx_core.c | 8 ++++---- drivers/scsi/aic7xxx/aic7xxx_seq.h_shipped | 3 +-- drivers/scsi/aic7xxx/aicasm/aicasm.c | 6 ++++-- 5 files changed, 14 insertions(+), 14 deletions(-)