| Message ID | 20220824020548.62625-11-rmclure@linux.ibm.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | powerpc: Syscall wrapper and register clearing | expand |
On Wed Aug 24, 2022 at 12:05 PM AEST, Rohan McLure wrote: > Cause syscall handlers to be typed as follows when called indirectly > throughout the kernel. > > typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long, > unsigned long, unsigned long, unsigned long); The point is... better type checking? > > Since both 32 and 64-bit abis allow for at least the first six > machine-word length parameters to a function to be passed by registers, > even handlers which admit fewer than six parameters may be viewed as > having the above type. > > Fixup comparisons in VDSO to avoid pointer-integer comparison. Introduce > explicit cast on systems with SPUs. > > Signed-off-by: Rohan McLure <rmclure@linux.ibm.com> > --- > V1 -> V2: New patch. > V2 -> V3: Remove unnecessary cast from const syscall_fn to syscall_fn > --- > arch/powerpc/include/asm/syscall.h | 7 +++++-- > arch/powerpc/include/asm/syscalls.h | 1 + > arch/powerpc/kernel/systbl.c | 6 +++--- > arch/powerpc/kernel/vdso.c | 4 ++-- > arch/powerpc/platforms/cell/spu_callbacks.c | 6 +++--- > 5 files changed, 14 insertions(+), 10 deletions(-) > > diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h > index 25fc8ad9a27a..d2a8dfd5de33 100644 > --- a/arch/powerpc/include/asm/syscall.h > +++ b/arch/powerpc/include/asm/syscall.h > @@ -14,9 +14,12 @@ > #include <linux/sched.h> > #include <linux/thread_info.h> > > +typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long, > + unsigned long, unsigned long, unsigned long); > + > /* ftrace syscalls requires exporting the sys_call_table */ > -extern const unsigned long sys_call_table[]; > -extern const unsigned long compat_sys_call_table[]; > +extern const syscall_fn sys_call_table[]; > +extern const syscall_fn compat_sys_call_table[]; Ah you constify it in this patch. I think the previous patch should have kept the const, and it should keep the unsigned long type rather than use void *. Either that or do this patch first. > static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs) > { > diff --git a/arch/powerpc/include/asm/syscalls.h b/arch/powerpc/include/asm/syscalls.h > index 91417dee534e..e979b7593d2b 100644 > --- a/arch/powerpc/include/asm/syscalls.h > +++ b/arch/powerpc/include/asm/syscalls.h > @@ -8,6 +8,7 @@ > #include <linux/types.h> > #include <linux/compat.h> > > +#include <asm/syscall.h> > #ifdef CONFIG_PPC64 > #include <asm/syscalls_32.h> > #endif Is this necessary or should be in another patch? > diff --git a/arch/powerpc/kernel/systbl.c b/arch/powerpc/kernel/systbl.c > index 99ffdfef6b9c..b88a9c2a1f50 100644 > --- a/arch/powerpc/kernel/systbl.c > +++ b/arch/powerpc/kernel/systbl.c > @@ -21,10 +21,10 @@ > #define __SYSCALL(nr, entry) [nr] = __powerpc_##entry, > #define __powerpc_sys_ni_syscall sys_ni_syscall > #else > -#define __SYSCALL(nr, entry) [nr] = entry, > +#define __SYSCALL(nr, entry) [nr] = (void *) entry, > #endif Also perhaps this should have been in the prior pach and this pach should change the cast from void to syscall_fn ? > > -void *sys_call_table[] = { > +const syscall_fn sys_call_table[] = { > #ifdef CONFIG_PPC64 > #include <asm/syscall_table_64.h> > #else > @@ -35,7 +35,7 @@ void *sys_call_table[] = { > #ifdef CONFIG_COMPAT > #undef __SYSCALL_WITH_COMPAT > #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat) > -void *compat_sys_call_table[] = { > +const syscall_fn compat_sys_call_table[] = { > #include <asm/syscall_table_32.h> > }; > #endif /* CONFIG_COMPAT */ > diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c > index 0da287544054..080c9e7de0c0 100644 > --- a/arch/powerpc/kernel/vdso.c > +++ b/arch/powerpc/kernel/vdso.c > @@ -313,10 +313,10 @@ static void __init vdso_setup_syscall_map(void) > unsigned int i; > > for (i = 0; i < NR_syscalls; i++) { > - if (sys_call_table[i] != (unsigned long)&sys_ni_syscall) > + if (sys_call_table[i] != (void *)&sys_ni_syscall) > vdso_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); > if (IS_ENABLED(CONFIG_COMPAT) && > - compat_sys_call_table[i] != (unsigned long)&sys_ni_syscall) > + compat_sys_call_table[i] != (void *)&sys_ni_syscall) Also these. Thanks, Nick > vdso_data->compat_syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); > } > } > diff --git a/arch/powerpc/platforms/cell/spu_callbacks.c b/arch/powerpc/platforms/cell/spu_callbacks.c > index fe0d8797a00a..e780c14c5733 100644 > --- a/arch/powerpc/platforms/cell/spu_callbacks.c > +++ b/arch/powerpc/platforms/cell/spu_callbacks.c > @@ -34,15 +34,15 @@ > * mbind, mq_open, ipc, ... > */ > > -static void *spu_syscall_table[] = { > +static const syscall_fn spu_syscall_table[] = { > #define __SYSCALL_WITH_COMPAT(nr, entry, compat) __SYSCALL(nr, entry) > -#define __SYSCALL(nr, entry) [nr] = entry, > +#define __SYSCALL(nr, entry) [nr] = (void *) entry, > #include <asm/syscall_table_spu.h> > }; > > long spu_sys_callback(struct spu_syscall_block *s) > { > - long (*syscall)(u64 a1, u64 a2, u64 a3, u64 a4, u64 a5, u64 a6); > + syscall_fn syscall; > > if (s->nr_ret >= ARRAY_SIZE(spu_syscall_table)) { > pr_debug("%s: invalid syscall #%lld", __func__, s->nr_ret); > -- > 2.34.1
> On 12 Sep 2022, at 8:56 pm, Nicholas Piggin <npiggin@gmail.com> wrote: > > On Wed Aug 24, 2022 at 12:05 PM AEST, Rohan McLure wrote: >> Cause syscall handlers to be typed as follows when called indirectly >> throughout the kernel. >> >> typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long, >> unsigned long, unsigned long, unsigned long); > > The point is... better type checking? > >> >> Since both 32 and 64-bit abis allow for at least the first six >> machine-word length parameters to a function to be passed by registers, >> even handlers which admit fewer than six parameters may be viewed as >> having the above type. >> >> Fixup comparisons in VDSO to avoid pointer-integer comparison. Introduce >> explicit cast on systems with SPUs. >> >> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com> >> --- >> V1 -> V2: New patch. >> V2 -> V3: Remove unnecessary cast from const syscall_fn to syscall_fn >> --- >> arch/powerpc/include/asm/syscall.h | 7 +++++-- >> arch/powerpc/include/asm/syscalls.h | 1 + >> arch/powerpc/kernel/systbl.c | 6 +++--- >> arch/powerpc/kernel/vdso.c | 4 ++-- >> arch/powerpc/platforms/cell/spu_callbacks.c | 6 +++--- >> 5 files changed, 14 insertions(+), 10 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h >> index 25fc8ad9a27a..d2a8dfd5de33 100644 >> --- a/arch/powerpc/include/asm/syscall.h >> +++ b/arch/powerpc/include/asm/syscall.h >> @@ -14,9 +14,12 @@ >> #include <linux/sched.h> >> #include <linux/thread_info.h> >> >> +typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long, >> + unsigned long, unsigned long, unsigned long); >> + >> /* ftrace syscalls requires exporting the sys_call_table */ >> -extern const unsigned long sys_call_table[]; >> -extern const unsigned long compat_sys_call_table[]; >> +extern const syscall_fn sys_call_table[]; >> +extern const syscall_fn compat_sys_call_table[]; > > Ah you constify it in this patch. I think the previous patch should have > kept the const, and it should keep the unsigned long type rather than > use void *. Either that or do this patch first. > >> static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs) >> { >> diff --git a/arch/powerpc/include/asm/syscalls.h b/arch/powerpc/include/asm/syscalls.h >> index 91417dee534e..e979b7593d2b 100644 >> --- a/arch/powerpc/include/asm/syscalls.h >> +++ b/arch/powerpc/include/asm/syscalls.h >> @@ -8,6 +8,7 @@ >> #include <linux/types.h> >> #include <linux/compat.h> >> >> +#include <asm/syscall.h> >> #ifdef CONFIG_PPC64 >> #include <asm/syscalls_32.h> >> #endif > > Is this necessary or should be in another patch? Good spot. This belongs in the patch that produces systbl.c. > >> diff --git a/arch/powerpc/kernel/systbl.c b/arch/powerpc/kernel/systbl.c >> index 99ffdfef6b9c..b88a9c2a1f50 100644 >> --- a/arch/powerpc/kernel/systbl.c >> +++ b/arch/powerpc/kernel/systbl.c >> @@ -21,10 +21,10 @@ >> #define __SYSCALL(nr, entry) [nr] = __powerpc_##entry, >> #define __powerpc_sys_ni_syscall sys_ni_syscall >> #else >> -#define __SYSCALL(nr, entry) [nr] = entry, >> +#define __SYSCALL(nr, entry) [nr] = (void *) entry, >> #endif > > Also perhaps this should have been in the prior pach and this pach > should change the cast from void to syscall_fn ? This cast to (void *) kicks in when casting functions with six or fewer parameters to six-parameter type accepting and returning u64. Sadly I can’t find a way to avoid -Wcast-function-type even with (__force syscall_fn) short of an ugly casti to void* here. Any suggestions? > >> >> -void *sys_call_table[] = { >> +const syscall_fn sys_call_table[] = { >> #ifdef CONFIG_PPC64 >> #include <asm/syscall_table_64.h> >> #else >> @@ -35,7 +35,7 @@ void *sys_call_table[] = { >> #ifdef CONFIG_COMPAT >> #undef __SYSCALL_WITH_COMPAT >> #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat) >> -void *compat_sys_call_table[] = { >> +const syscall_fn compat_sys_call_table[] = { >> #include <asm/syscall_table_32.h> >> }; >> #endif /* CONFIG_COMPAT */ >> diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c >> index 0da287544054..080c9e7de0c0 100644 >> --- a/arch/powerpc/kernel/vdso.c >> +++ b/arch/powerpc/kernel/vdso.c >> @@ -313,10 +313,10 @@ static void __init vdso_setup_syscall_map(void) >> unsigned int i; >> >> for (i = 0; i < NR_syscalls; i++) { >> - if (sys_call_table[i] != (unsigned long)&sys_ni_syscall) >> + if (sys_call_table[i] != (void *)&sys_ni_syscall) >> vdso_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); >> if (IS_ENABLED(CONFIG_COMPAT) && >> - compat_sys_call_table[i] != (unsigned long)&sys_ni_syscall) >> + compat_sys_call_table[i] != (void *)&sys_ni_syscall) > > Also these. > > Thanks, > Nick > >> vdso_data->compat_syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); >> } >> } >> diff --git a/arch/powerpc/platforms/cell/spu_callbacks.c b/arch/powerpc/platforms/cell/spu_callbacks.c >> index fe0d8797a00a..e780c14c5733 100644 >> --- a/arch/powerpc/platforms/cell/spu_callbacks.c >> +++ b/arch/powerpc/platforms/cell/spu_callbacks.c >> @@ -34,15 +34,15 @@ >> * mbind, mq_open, ipc, ... >> */ >> >> -static void *spu_syscall_table[] = { >> +static const syscall_fn spu_syscall_table[] = { >> #define __SYSCALL_WITH_COMPAT(nr, entry, compat) __SYSCALL(nr, entry) >> -#define __SYSCALL(nr, entry) [nr] = entry, >> +#define __SYSCALL(nr, entry) [nr] = (void *) entry, >> #include <asm/syscall_table_spu.h> >> }; >> >> long spu_sys_callback(struct spu_syscall_block *s) >> { >> - long (*syscall)(u64 a1, u64 a2, u64 a3, u64 a4, u64 a5, u64 a6); >> + syscall_fn syscall; >> >> if (s->nr_ret >= ARRAY_SIZE(spu_syscall_table)) { >> pr_debug("%s: invalid syscall #%lld", __func__, s->nr_ret); >> -- >> 2.34.1
On Thu Sep 15, 2022 at 3:45 PM AEST, Rohan McLure wrote: > > > > On 12 Sep 2022, at 8:56 pm, Nicholas Piggin <npiggin@gmail.com> wrote: > > > > On Wed Aug 24, 2022 at 12:05 PM AEST, Rohan McLure wrote: > >> Cause syscall handlers to be typed as follows when called indirectly > >> throughout the kernel. > >> > >> typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long, > >> unsigned long, unsigned long, unsigned long); > > > > The point is... better type checking? > > > >> > >> Since both 32 and 64-bit abis allow for at least the first six > >> machine-word length parameters to a function to be passed by registers, > >> even handlers which admit fewer than six parameters may be viewed as > >> having the above type. > >> > >> Fixup comparisons in VDSO to avoid pointer-integer comparison. Introduce > >> explicit cast on systems with SPUs. > >> > >> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com> > >> --- > >> V1 -> V2: New patch. > >> V2 -> V3: Remove unnecessary cast from const syscall_fn to syscall_fn > >> --- > >> arch/powerpc/include/asm/syscall.h | 7 +++++-- > >> arch/powerpc/include/asm/syscalls.h | 1 + > >> arch/powerpc/kernel/systbl.c | 6 +++--- > >> arch/powerpc/kernel/vdso.c | 4 ++-- > >> arch/powerpc/platforms/cell/spu_callbacks.c | 6 +++--- > >> 5 files changed, 14 insertions(+), 10 deletions(-) > >> > >> diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h > >> index 25fc8ad9a27a..d2a8dfd5de33 100644 > >> --- a/arch/powerpc/include/asm/syscall.h > >> +++ b/arch/powerpc/include/asm/syscall.h > >> @@ -14,9 +14,12 @@ > >> #include <linux/sched.h> > >> #include <linux/thread_info.h> > >> > >> +typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long, > >> + unsigned long, unsigned long, unsigned long); > >> + > >> /* ftrace syscalls requires exporting the sys_call_table */ > >> -extern const unsigned long sys_call_table[]; > >> -extern const unsigned long compat_sys_call_table[]; > >> +extern const syscall_fn sys_call_table[]; > >> +extern const syscall_fn compat_sys_call_table[]; > > > > Ah you constify it in this patch. I think the previous patch should have > > kept the const, and it should keep the unsigned long type rather than > > use void *. Either that or do this patch first. > > > >> static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs) > >> { > >> diff --git a/arch/powerpc/include/asm/syscalls.h b/arch/powerpc/include/asm/syscalls.h > >> index 91417dee534e..e979b7593d2b 100644 > >> --- a/arch/powerpc/include/asm/syscalls.h > >> +++ b/arch/powerpc/include/asm/syscalls.h > >> @@ -8,6 +8,7 @@ > >> #include <linux/types.h> > >> #include <linux/compat.h> > >> > >> +#include <asm/syscall.h> > >> #ifdef CONFIG_PPC64 > >> #include <asm/syscalls_32.h> > >> #endif > > > > Is this necessary or should be in another patch? > > Good spot. This belongs in the patch that produces systbl.c. > > > > >> diff --git a/arch/powerpc/kernel/systbl.c b/arch/powerpc/kernel/systbl.c > >> index 99ffdfef6b9c..b88a9c2a1f50 100644 > >> --- a/arch/powerpc/kernel/systbl.c > >> +++ b/arch/powerpc/kernel/systbl.c > >> @@ -21,10 +21,10 @@ > >> #define __SYSCALL(nr, entry) [nr] = __powerpc_##entry, > >> #define __powerpc_sys_ni_syscall sys_ni_syscall > >> #else > >> -#define __SYSCALL(nr, entry) [nr] = entry, > >> +#define __SYSCALL(nr, entry) [nr] = (void *) entry, > >> #endif > > > > Also perhaps this should have been in the prior pach and this pach > > should change the cast from void to syscall_fn ? > > This cast to (void *) kicks in when casting functions with six or fewer Right, I was just wondering if it needs to be in the previous patch because that's where you changed the type from unsigned long to void *. Maybe there's some reason it's not required, I didn't entirely follow all the macro expansion. > parameters to six-parameter type accepting and returning u64. Sadly I can’t > find a way to avoid -Wcast-function-type even with (__force syscall_fn) short > of an ugly casti to void* here. Any suggestions? Ah okay. I think __force is a sparse specific attribute. Not sure if gcc/clang can do it. There is a diag thing which maybe can turn off warnings selectively, but if (void *) is turning off the warning selectively then there would be no benefit to using it :) That's fine to keep using void *. Thanks, Nick
diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h index 25fc8ad9a27a..d2a8dfd5de33 100644 --- a/arch/powerpc/include/asm/syscall.h +++ b/arch/powerpc/include/asm/syscall.h @@ -14,9 +14,12 @@ #include <linux/sched.h> #include <linux/thread_info.h> +typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long, + unsigned long, unsigned long, unsigned long); + /* ftrace syscalls requires exporting the sys_call_table */ -extern const unsigned long sys_call_table[]; -extern const unsigned long compat_sys_call_table[]; +extern const syscall_fn sys_call_table[]; +extern const syscall_fn compat_sys_call_table[]; static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs) { diff --git a/arch/powerpc/include/asm/syscalls.h b/arch/powerpc/include/asm/syscalls.h index 91417dee534e..e979b7593d2b 100644 --- a/arch/powerpc/include/asm/syscalls.h +++ b/arch/powerpc/include/asm/syscalls.h @@ -8,6 +8,7 @@ #include <linux/types.h> #include <linux/compat.h> +#include <asm/syscall.h> #ifdef CONFIG_PPC64 #include <asm/syscalls_32.h> #endif diff --git a/arch/powerpc/kernel/systbl.c b/arch/powerpc/kernel/systbl.c index 99ffdfef6b9c..b88a9c2a1f50 100644 --- a/arch/powerpc/kernel/systbl.c +++ b/arch/powerpc/kernel/systbl.c @@ -21,10 +21,10 @@ #define __SYSCALL(nr, entry) [nr] = __powerpc_##entry, #define __powerpc_sys_ni_syscall sys_ni_syscall #else -#define __SYSCALL(nr, entry) [nr] = entry, +#define __SYSCALL(nr, entry) [nr] = (void *) entry, #endif -void *sys_call_table[] = { +const syscall_fn sys_call_table[] = { #ifdef CONFIG_PPC64 #include <asm/syscall_table_64.h> #else @@ -35,7 +35,7 @@ void *sys_call_table[] = { #ifdef CONFIG_COMPAT #undef __SYSCALL_WITH_COMPAT #define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat) -void *compat_sys_call_table[] = { +const syscall_fn compat_sys_call_table[] = { #include <asm/syscall_table_32.h> }; #endif /* CONFIG_COMPAT */ diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c index 0da287544054..080c9e7de0c0 100644 --- a/arch/powerpc/kernel/vdso.c +++ b/arch/powerpc/kernel/vdso.c @@ -313,10 +313,10 @@ static void __init vdso_setup_syscall_map(void) unsigned int i; for (i = 0; i < NR_syscalls; i++) { - if (sys_call_table[i] != (unsigned long)&sys_ni_syscall) + if (sys_call_table[i] != (void *)&sys_ni_syscall) vdso_data->syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); if (IS_ENABLED(CONFIG_COMPAT) && - compat_sys_call_table[i] != (unsigned long)&sys_ni_syscall) + compat_sys_call_table[i] != (void *)&sys_ni_syscall) vdso_data->compat_syscall_map[i >> 5] |= 0x80000000UL >> (i & 0x1f); } } diff --git a/arch/powerpc/platforms/cell/spu_callbacks.c b/arch/powerpc/platforms/cell/spu_callbacks.c index fe0d8797a00a..e780c14c5733 100644 --- a/arch/powerpc/platforms/cell/spu_callbacks.c +++ b/arch/powerpc/platforms/cell/spu_callbacks.c @@ -34,15 +34,15 @@ * mbind, mq_open, ipc, ... */ -static void *spu_syscall_table[] = { +static const syscall_fn spu_syscall_table[] = { #define __SYSCALL_WITH_COMPAT(nr, entry, compat) __SYSCALL(nr, entry) -#define __SYSCALL(nr, entry) [nr] = entry, +#define __SYSCALL(nr, entry) [nr] = (void *) entry, #include <asm/syscall_table_spu.h> }; long spu_sys_callback(struct spu_syscall_block *s) { - long (*syscall)(u64 a1, u64 a2, u64 a3, u64 a4, u64 a5, u64 a6); + syscall_fn syscall; if (s->nr_ret >= ARRAY_SIZE(spu_syscall_table)) { pr_debug("%s: invalid syscall #%lld", __func__, s->nr_ret);
Cause syscall handlers to be typed as follows when called indirectly throughout the kernel. typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); Since both 32 and 64-bit abis allow for at least the first six machine-word length parameters to a function to be passed by registers, even handlers which admit fewer than six parameters may be viewed as having the above type. Fixup comparisons in VDSO to avoid pointer-integer comparison. Introduce explicit cast on systems with SPUs. Signed-off-by: Rohan McLure <rmclure@linux.ibm.com> --- V1 -> V2: New patch. V2 -> V3: Remove unnecessary cast from const syscall_fn to syscall_fn --- arch/powerpc/include/asm/syscall.h | 7 +++++-- arch/powerpc/include/asm/syscalls.h | 1 + arch/powerpc/kernel/systbl.c | 6 +++--- arch/powerpc/kernel/vdso.c | 4 ++-- arch/powerpc/platforms/cell/spu_callbacks.c | 6 +++--- 5 files changed, 14 insertions(+), 10 deletions(-)