Re: [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32
On Fri, Apr 03, 2020 at 05:13:25PM +1000, Nicholas Piggin wrote:
> Michal Suchánek's on March 25, 2020 5:38 am:
> > On Tue, Mar 24, 2020 at 06:48:20PM +1000, Nicholas Piggin wrote:
> >> Michal Suchanek's on March 19, 2020 10:19 pm:
> >> > There are two almost identical copies for 32bit and 64bit.
> >> >
> >> > The function is used only in 32bit code which will be split out in next
> >> > patch so consolidate to one function.
> >> >
> >> > Signed-off-by: Michal Suchanek
> >> > Reviewed-by: Christophe Leroy
> >> > ---
> >> > v6: new patch
> >> > v8: move the consolidated function out of the ifdef block.
> >> > v11: rebase on top of def0bfdbd603
> >> > ---
> >> > arch/powerpc/perf/callchain.c | 48 +--
> >> > 1 file changed, 24 insertions(+), 24 deletions(-)
> >> >
> >> > diff --git a/arch/powerpc/perf/callchain.c
> >> > b/arch/powerpc/perf/callchain.c
> >> > index cbc251981209..c9a78c6e4361 100644
> >> > --- a/arch/powerpc/perf/callchain.c
> >> > +++ b/arch/powerpc/perf/callchain.c
> >> > @@ -161,18 +161,6 @@ static int read_user_stack_64(unsigned long __user
> >> > *ptr, unsigned long *ret)
> >> > return read_user_stack_slow(ptr, ret, 8);
> >> > }
> >> >
> >> > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int
> >> > *ret)
> >> > -{
> >> > -if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> >> > -((unsigned long)ptr & 3))
> >> > -return -EFAULT;
> >> > -
> >> > -if (!probe_user_read(ret, ptr, sizeof(*ret)))
> >> > -return 0;
> >> > -
> >> > -return read_user_stack_slow(ptr, ret, 4);
> >> > -}
> >> > -
> >> > static inline int valid_user_sp(unsigned long sp, int is_64)
> >> > {
> >> > if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x1UL)
> >> > - 32)
> >> > @@ -277,19 +265,9 @@ static void perf_callchain_user_64(struct
> >> > perf_callchain_entry_ctx *entry,
> >> > }
> >> >
> >> > #else /* CONFIG_PPC64 */
> >> > -/*
> >> > - * On 32-bit we just access the address and let hash_page create a
> >> > - * HPTE if necessary, so there is no need to fall back to reading
> >> > - * the page tables. Since this is called at interrupt level,
> >> > - * do_page_fault() won't treat a DSI as a page fault.
> >> > - */
> >> > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int
> >> > *ret)
> >> > +static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
> >> > {
> >> > -if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> >> > -((unsigned long)ptr & 3))
> >> > -return -EFAULT;
> >> > -
> >> > -return probe_user_read(ret, ptr, sizeof(*ret));
> >> > +return 0;
> >> > }
> >> >
> >> > static inline void perf_callchain_user_64(struct
> >> > perf_callchain_entry_ctx *entry,
> >> > @@ -312,6 +290,28 @@ static inline int valid_user_sp(unsigned long sp,
> >> > int is_64)
> >> >
> >> > #endif /* CONFIG_PPC64 */
> >> >
> >> > +/*
> >> > + * On 32-bit we just access the address and let hash_page create a
> >> > + * HPTE if necessary, so there is no need to fall back to reading
> >> > + * the page tables. Since this is called at interrupt level,
> >> > + * do_page_fault() won't treat a DSI as a page fault.
> >> > + */
> >>
> >> The comment is actually probably better to stay in the 32-bit
> >> read_user_stack_slow implementation. Is that function defined
> >> on 32-bit purely so that you can use IS_ENABLED()? In that case
> > It documents the IS_ENABLED() and that's where it is. The 32bit
> > definition is only a technical detail.
>
> Sorry for the late reply, busy trying to fix bugs in the C rewrite
> series. I don't think it is the right place, it should be in the
> ppc32 implementation detail.
Which does not exist anymore after the 32bit and 64bit part is split.
> ppc64 has an equivalent comment at the top of its read_user_stack functions.
>
> >> I would prefer to put a BUG() there which makes it self documenting.
> > Which will cause checkpatch complaints about introducing new BUG() which
> > is frowned on.
>
> It's fine in this case, that warning is about not introducing
> runtime bugs, but this wouldn't be.
>
> But... I actually don't like adding read_user_stack_slow on 32-bit
> and especially not just to make IS_ENABLED work.
That's to not break build at this point. Later the function is removed.
>
> IMO this would be better if you really want to consolidate it
>
> ---
>
> diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
> index cbc251981209..ca3a599b3f54 100644
> --- a/arch/powerpc/perf/callchain.c
> +++ b/arch/powerpc/perf/callchain.c
> @@ -108,7 +108,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx
> *entry, struct pt_regs *re
> * interrupt context, so if the access faults, we read the page tables
> * to find which page (if any) is mapped and access it directly.
> */
> -static int
Re: [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32
On Fri, Apr 03, 2020 at 09:26:27PM +1000, Nicholas Piggin wrote:
> Michal Suchánek's on April 3, 2020 8:52 pm:
> > Hello,
> >
> > there are 3 variants of the function
> >
> > read_user_stack_64
> >
> > 32bit read_user_stack_32
> > 64bit read_user_Stack_32
>
> Right.
>
> > On Fri, Apr 03, 2020 at 05:13:25PM +1000, Nicholas Piggin wrote:
> [...]
> >> #endif /* CONFIG_PPC64 */
> >>
> >> +static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> >> +{
> >> + return __read_user_stack(ptr, ret, sizeof(*ret));
> > Does not work for 64bit read_user_stack_32 ^ this should be 4.
> >
> > Other than that it should preserve the existing logic just fine.
>
> sizeof(int) == 4 on 64bit so it should work.
>
Right, the type is different for the 32bit and 64bit version.
Thanks
Michal
Re: [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32
Michal Suchánek's on April 3, 2020 8:52 pm:
> Hello,
>
> there are 3 variants of the function
>
> read_user_stack_64
>
> 32bit read_user_stack_32
> 64bit read_user_Stack_32
Right.
> On Fri, Apr 03, 2020 at 05:13:25PM +1000, Nicholas Piggin wrote:
[...]
>> #endif /* CONFIG_PPC64 */
>>
>> +static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
>> +{
>> +return __read_user_stack(ptr, ret, sizeof(*ret));
> Does not work for 64bit read_user_stack_32 ^ this should be 4.
>
> Other than that it should preserve the existing logic just fine.
sizeof(int) == 4 on 64bit so it should work.
Thanks,
Nick
Re: [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32
Hello,
there are 3 variants of the function
read_user_stack_64
32bit read_user_stack_32
64bit read_user_Stack_32
On Fri, Apr 03, 2020 at 05:13:25PM +1000, Nicholas Piggin wrote:
> Michal Suchánek's on March 25, 2020 5:38 am:
> > On Tue, Mar 24, 2020 at 06:48:20PM +1000, Nicholas Piggin wrote:
> >> Michal Suchanek's on March 19, 2020 10:19 pm:
> >> > There are two almost identical copies for 32bit and 64bit.
> >> >
> >> > The function is used only in 32bit code which will be split out in next
> >> > patch so consolidate to one function.
> >> >
> >> > Signed-off-by: Michal Suchanek
> >> > Reviewed-by: Christophe Leroy
> >> > ---
> >> > v6: new patch
> >> > v8: move the consolidated function out of the ifdef block.
> >> > v11: rebase on top of def0bfdbd603
> >> > ---
> >> > arch/powerpc/perf/callchain.c | 48 +--
> >> > 1 file changed, 24 insertions(+), 24 deletions(-)
> >> >
> >> > diff --git a/arch/powerpc/perf/callchain.c
> >> > b/arch/powerpc/perf/callchain.c
> >> > index cbc251981209..c9a78c6e4361 100644
> >> > --- a/arch/powerpc/perf/callchain.c
> >> > +++ b/arch/powerpc/perf/callchain.c
> >> > @@ -161,18 +161,6 @@ static int read_user_stack_64(unsigned long __user
> >> > *ptr, unsigned long *ret)
> >> > return read_user_stack_slow(ptr, ret, 8);
> >> > }
> >> >
> >> > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int
> >> > *ret)
> >> > -{
> >> > -if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> >> > -((unsigned long)ptr & 3))
> >> > -return -EFAULT;
> >> > -
> >> > -if (!probe_user_read(ret, ptr, sizeof(*ret)))
> >> > -return 0;
> >> > -
> >> > -return read_user_stack_slow(ptr, ret, 4);
> >> > -}
> >> > -
> >> > static inline int valid_user_sp(unsigned long sp, int is_64)
> >> > {
> >> > if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x1UL)
> >> > - 32)
> >> > @@ -277,19 +265,9 @@ static void perf_callchain_user_64(struct
> >> > perf_callchain_entry_ctx *entry,
> >> > }
> >> >
> >> > #else /* CONFIG_PPC64 */
> >> > -/*
> >> > - * On 32-bit we just access the address and let hash_page create a
> >> > - * HPTE if necessary, so there is no need to fall back to reading
> >> > - * the page tables. Since this is called at interrupt level,
> >> > - * do_page_fault() won't treat a DSI as a page fault.
> >> > - */
> >> > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int
> >> > *ret)
> >> > +static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
> >> > {
> >> > -if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> >> > -((unsigned long)ptr & 3))
> >> > -return -EFAULT;
> >> > -
> >> > -return probe_user_read(ret, ptr, sizeof(*ret));
> >> > +return 0;
> >> > }
> >> >
> >> > static inline void perf_callchain_user_64(struct
> >> > perf_callchain_entry_ctx *entry,
> >> > @@ -312,6 +290,28 @@ static inline int valid_user_sp(unsigned long sp,
> >> > int is_64)
> >> >
> >> > #endif /* CONFIG_PPC64 */
> >> >
> >> > +/*
> >> > + * On 32-bit we just access the address and let hash_page create a
> >> > + * HPTE if necessary, so there is no need to fall back to reading
> >> > + * the page tables. Since this is called at interrupt level,
> >> > + * do_page_fault() won't treat a DSI as a page fault.
> >> > + */
> >>
> >> The comment is actually probably better to stay in the 32-bit
> >> read_user_stack_slow implementation. Is that function defined
> >> on 32-bit purely so that you can use IS_ENABLED()? In that case
> > It documents the IS_ENABLED() and that's where it is. The 32bit
> > definition is only a technical detail.
>
> Sorry for the late reply, busy trying to fix bugs in the C rewrite
> series. I don't think it is the right place, it should be in the
> ppc32 implementation detail. ppc64 has an equivalent comment at the
> top of its read_user_stack functions.
>
> >> I would prefer to put a BUG() there which makes it self documenting.
> > Which will cause checkpatch complaints about introducing new BUG() which
> > is frowned on.
>
> It's fine in this case, that warning is about not introducing
> runtime bugs, but this wouldn't be.
>
> But... I actually don't like adding read_user_stack_slow on 32-bit
> and especially not just to make IS_ENABLED work.
>
> IMO this would be better if you really want to consolidate it
>
> ---
>
> diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
> index cbc251981209..ca3a599b3f54 100644
> --- a/arch/powerpc/perf/callchain.c
> +++ b/arch/powerpc/perf/callchain.c
> @@ -108,7 +108,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx
> *entry, struct pt_regs *re
> * interrupt context, so if the access faults, we read the page tables
> * to find which page (if any) is mapped and access it directly.
> */
> -static int read_user_stack_slow(void __user
Re: [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32
Michal Suchánek's on March 25, 2020 5:38 am:
> On Tue, Mar 24, 2020 at 06:48:20PM +1000, Nicholas Piggin wrote:
>> Michal Suchanek's on March 19, 2020 10:19 pm:
>> > There are two almost identical copies for 32bit and 64bit.
>> >
>> > The function is used only in 32bit code which will be split out in next
>> > patch so consolidate to one function.
>> >
>> > Signed-off-by: Michal Suchanek
>> > Reviewed-by: Christophe Leroy
>> > ---
>> > v6: new patch
>> > v8: move the consolidated function out of the ifdef block.
>> > v11: rebase on top of def0bfdbd603
>> > ---
>> > arch/powerpc/perf/callchain.c | 48 +--
>> > 1 file changed, 24 insertions(+), 24 deletions(-)
>> >
>> > diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
>> > index cbc251981209..c9a78c6e4361 100644
>> > --- a/arch/powerpc/perf/callchain.c
>> > +++ b/arch/powerpc/perf/callchain.c
>> > @@ -161,18 +161,6 @@ static int read_user_stack_64(unsigned long __user
>> > *ptr, unsigned long *ret)
>> >return read_user_stack_slow(ptr, ret, 8);
>> > }
>> >
>> > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
>> > -{
>> > - if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
>> > - ((unsigned long)ptr & 3))
>> > - return -EFAULT;
>> > -
>> > - if (!probe_user_read(ret, ptr, sizeof(*ret)))
>> > - return 0;
>> > -
>> > - return read_user_stack_slow(ptr, ret, 4);
>> > -}
>> > -
>> > static inline int valid_user_sp(unsigned long sp, int is_64)
>> > {
>> >if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x1UL) - 32)
>> > @@ -277,19 +265,9 @@ static void perf_callchain_user_64(struct
>> > perf_callchain_entry_ctx *entry,
>> > }
>> >
>> > #else /* CONFIG_PPC64 */
>> > -/*
>> > - * On 32-bit we just access the address and let hash_page create a
>> > - * HPTE if necessary, so there is no need to fall back to reading
>> > - * the page tables. Since this is called at interrupt level,
>> > - * do_page_fault() won't treat a DSI as a page fault.
>> > - */
>> > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
>> > +static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
>> > {
>> > - if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
>> > - ((unsigned long)ptr & 3))
>> > - return -EFAULT;
>> > -
>> > - return probe_user_read(ret, ptr, sizeof(*ret));
>> > + return 0;
>> > }
>> >
>> > static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx
>> > *entry,
>> > @@ -312,6 +290,28 @@ static inline int valid_user_sp(unsigned long sp, int
>> > is_64)
>> >
>> > #endif /* CONFIG_PPC64 */
>> >
>> > +/*
>> > + * On 32-bit we just access the address and let hash_page create a
>> > + * HPTE if necessary, so there is no need to fall back to reading
>> > + * the page tables. Since this is called at interrupt level,
>> > + * do_page_fault() won't treat a DSI as a page fault.
>> > + */
>>
>> The comment is actually probably better to stay in the 32-bit
>> read_user_stack_slow implementation. Is that function defined
>> on 32-bit purely so that you can use IS_ENABLED()? In that case
> It documents the IS_ENABLED() and that's where it is. The 32bit
> definition is only a technical detail.
Sorry for the late reply, busy trying to fix bugs in the C rewrite
series. I don't think it is the right place, it should be in the
ppc32 implementation detail. ppc64 has an equivalent comment at the
top of its read_user_stack functions.
>> I would prefer to put a BUG() there which makes it self documenting.
> Which will cause checkpatch complaints about introducing new BUG() which
> is frowned on.
It's fine in this case, that warning is about not introducing
runtime bugs, but this wouldn't be.
But... I actually don't like adding read_user_stack_slow on 32-bit
and especially not just to make IS_ENABLED work.
IMO this would be better if you really want to consolidate it
---
diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
index cbc251981209..ca3a599b3f54 100644
--- a/arch/powerpc/perf/callchain.c
+++ b/arch/powerpc/perf/callchain.c
@@ -108,7 +108,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx
*entry, struct pt_regs *re
* interrupt context, so if the access faults, we read the page tables
* to find which page (if any) is mapped and access it directly.
*/
-static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
+static int read_user_stack_slow(const void __user *ptr, void *buf, int nb)
{
int ret = -EFAULT;
pgd_t *pgdir;
@@ -149,28 +149,21 @@ static int read_user_stack_slow(void __user *ptr, void
*buf, int nb)
return ret;
}
-static int read_user_stack_64(unsigned long __user *ptr, unsigned long *ret)
+static int __read_user_stack(const void __user *ptr, void *ret, size_t size)
{
- if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) ||
- ((unsigned
Re: [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32
On Tue, Mar 24, 2020 at 06:48:20PM +1000, Nicholas Piggin wrote:
> Michal Suchanek's on March 19, 2020 10:19 pm:
> > There are two almost identical copies for 32bit and 64bit.
> >
> > The function is used only in 32bit code which will be split out in next
> > patch so consolidate to one function.
> >
> > Signed-off-by: Michal Suchanek
> > Reviewed-by: Christophe Leroy
> > ---
> > v6: new patch
> > v8: move the consolidated function out of the ifdef block.
> > v11: rebase on top of def0bfdbd603
> > ---
> > arch/powerpc/perf/callchain.c | 48 +--
> > 1 file changed, 24 insertions(+), 24 deletions(-)
> >
> > diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
> > index cbc251981209..c9a78c6e4361 100644
> > --- a/arch/powerpc/perf/callchain.c
> > +++ b/arch/powerpc/perf/callchain.c
> > @@ -161,18 +161,6 @@ static int read_user_stack_64(unsigned long __user
> > *ptr, unsigned long *ret)
> > return read_user_stack_slow(ptr, ret, 8);
> > }
> >
> > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> > -{
> > - if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> > - ((unsigned long)ptr & 3))
> > - return -EFAULT;
> > -
> > - if (!probe_user_read(ret, ptr, sizeof(*ret)))
> > - return 0;
> > -
> > - return read_user_stack_slow(ptr, ret, 4);
> > -}
> > -
> > static inline int valid_user_sp(unsigned long sp, int is_64)
> > {
> > if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x1UL) - 32)
> > @@ -277,19 +265,9 @@ static void perf_callchain_user_64(struct
> > perf_callchain_entry_ctx *entry,
> > }
> >
> > #else /* CONFIG_PPC64 */
> > -/*
> > - * On 32-bit we just access the address and let hash_page create a
> > - * HPTE if necessary, so there is no need to fall back to reading
> > - * the page tables. Since this is called at interrupt level,
> > - * do_page_fault() won't treat a DSI as a page fault.
> > - */
> > -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> > +static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
> > {
> > - if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> > - ((unsigned long)ptr & 3))
> > - return -EFAULT;
> > -
> > - return probe_user_read(ret, ptr, sizeof(*ret));
> > + return 0;
> > }
> >
> > static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx
> > *entry,
> > @@ -312,6 +290,28 @@ static inline int valid_user_sp(unsigned long sp, int
> > is_64)
> >
> > #endif /* CONFIG_PPC64 */
> >
> > +/*
> > + * On 32-bit we just access the address and let hash_page create a
> > + * HPTE if necessary, so there is no need to fall back to reading
> > + * the page tables. Since this is called at interrupt level,
> > + * do_page_fault() won't treat a DSI as a page fault.
> > + */
>
> The comment is actually probably better to stay in the 32-bit
> read_user_stack_slow implementation. Is that function defined
> on 32-bit purely so that you can use IS_ENABLED()? In that case
It documents the IS_ENABLED() and that's where it is. The 32bit
definition is only a technical detail.
> I would prefer to put a BUG() there which makes it self documenting.
Which will cause checkpatch complaints about introducing new BUG() which
is frowned on.
Thanks
Michal
Re: [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32
Michal Suchanek's on March 19, 2020 10:19 pm:
> There are two almost identical copies for 32bit and 64bit.
>
> The function is used only in 32bit code which will be split out in next
> patch so consolidate to one function.
>
> Signed-off-by: Michal Suchanek
> Reviewed-by: Christophe Leroy
> ---
> v6: new patch
> v8: move the consolidated function out of the ifdef block.
> v11: rebase on top of def0bfdbd603
> ---
> arch/powerpc/perf/callchain.c | 48 +--
> 1 file changed, 24 insertions(+), 24 deletions(-)
>
> diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
> index cbc251981209..c9a78c6e4361 100644
> --- a/arch/powerpc/perf/callchain.c
> +++ b/arch/powerpc/perf/callchain.c
> @@ -161,18 +161,6 @@ static int read_user_stack_64(unsigned long __user *ptr,
> unsigned long *ret)
> return read_user_stack_slow(ptr, ret, 8);
> }
>
> -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> -{
> - if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> - ((unsigned long)ptr & 3))
> - return -EFAULT;
> -
> - if (!probe_user_read(ret, ptr, sizeof(*ret)))
> - return 0;
> -
> - return read_user_stack_slow(ptr, ret, 4);
> -}
> -
> static inline int valid_user_sp(unsigned long sp, int is_64)
> {
> if (!sp || (sp & 7) || sp > (is_64 ? TASK_SIZE : 0x1UL) - 32)
> @@ -277,19 +265,9 @@ static void perf_callchain_user_64(struct
> perf_callchain_entry_ctx *entry,
> }
>
> #else /* CONFIG_PPC64 */
> -/*
> - * On 32-bit we just access the address and let hash_page create a
> - * HPTE if necessary, so there is no need to fall back to reading
> - * the page tables. Since this is called at interrupt level,
> - * do_page_fault() won't treat a DSI as a page fault.
> - */
> -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> +static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
> {
> - if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> - ((unsigned long)ptr & 3))
> - return -EFAULT;
> -
> - return probe_user_read(ret, ptr, sizeof(*ret));
> + return 0;
> }
>
> static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx
> *entry,
> @@ -312,6 +290,28 @@ static inline int valid_user_sp(unsigned long sp, int
> is_64)
>
> #endif /* CONFIG_PPC64 */
>
> +/*
> + * On 32-bit we just access the address and let hash_page create a
> + * HPTE if necessary, so there is no need to fall back to reading
> + * the page tables. Since this is called at interrupt level,
> + * do_page_fault() won't treat a DSI as a page fault.
> + */
The comment is actually probably better to stay in the 32-bit
read_user_stack_slow implementation. Is that function defined
on 32-bit purely so that you can use IS_ENABLED()? In that case
I would prefer to put a BUG() there which makes it self documenting.
Thanks,
Nick
> +static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> +{
> + int rc;
> +
> + if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned int) ||
> + ((unsigned long)ptr & 3))
> + return -EFAULT;
> +
> + rc = probe_user_read(ret, ptr, sizeof(*ret));
> +
> + if (IS_ENABLED(CONFIG_PPC64) && rc)
> + return read_user_stack_slow(ptr, ret, 4);
> +
> + return rc;
> +}
> +
> /*
> * Layout for non-RT signal frames
> */
> --
> 2.23.0
>
>
