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SubjectRe: [PATCH v7 3/6] powerpc/perf: consolidate read_user_stack_32
Date
Michal Suchanek <msuchanek@suse.de> writes:

> 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 <msuchanek@suse.de>
> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> new patch in v6
> ---
> arch/powerpc/perf/callchain.c | 25 +++++++++----------------
> 1 file changed, 9 insertions(+), 16 deletions(-)
>
> diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
> index c84bbd4298a0..b7cdcce20280 100644
> --- a/arch/powerpc/perf/callchain.c
> +++ b/arch/powerpc/perf/callchain.c
> @@ -165,22 +165,6 @@ 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;
> -
> - pagefault_disable();
> - if (!__get_user_inatomic(*ret, ptr)) {
> - pagefault_enable();
> - return 0;
> - }
> - pagefault_enable();
> -
> - 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 : 0x100000000UL) - 32)
> @@ -295,6 +279,12 @@ static inline int current_is_64bit(void)
> }
>
> #else /* CONFIG_PPC64 */
> +static int read_user_stack_slow(void __user *ptr, void *buf, int nb)
> +{
> + return 0;
> +}
> +#endif /* CONFIG_PPC64 */

Ending the PPC64 else case here, and then restarting it below with an
ifndef means we end up with two parts of the file that define 32-bit
code, with a common chunk in the middle, which I dislike.

I'd rather you add the empty read_user_stack_slow() in the existing
#else section and then move read_user_stack_32() below the whole ifdef
PPC64/else/endif section.

Is there some reason that doesn't work?

cheers

> @@ -313,9 +303,12 @@ static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> rc = __get_user_inatomic(*ret, ptr);
> pagefault_enable();
>
> + if (IS_ENABLED(CONFIG_PPC64) && rc)
> + return read_user_stack_slow(ptr, ret, 4);
> return rc;
> }
>
> +#ifndef CONFIG_PPC64
> static inline void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
> struct pt_regs *regs)
> {
> --
> 2.22.0

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