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From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Michal Suchanek <msuchanek@suse.de>,
	linuxppc-dev@lists.ozlabs.org,
	Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpcs: perf: consolidate perf_callchain_user_64 and perf_callchain_user_32
Date: Tue, 7 Apr 2020 07:21:06 +0200	[thread overview]
Message-ID: <8786906b-edd5-e4a3-8286-33a05f39668c@c-s.fr> (raw)
In-Reply-To: <20200406210022.32265-1-msuchanek@suse.de>



Le 06/04/2020 à 23:00, Michal Suchanek a écrit :
> perf_callchain_user_64 and perf_callchain_user_32 are nearly identical.
> Consolidate into one function with thin wrappers.
> 
> Suggested-by: Nicholas Piggin <npiggin@gmail.com>
> Signed-off-by: Michal Suchanek <msuchanek@suse.de>
> ---
>   arch/powerpc/perf/callchain.h    | 24 +++++++++++++++++++++++-
>   arch/powerpc/perf/callchain_32.c | 21 ++-------------------
>   arch/powerpc/perf/callchain_64.c | 14 ++++----------
>   3 files changed, 29 insertions(+), 30 deletions(-)
> 
> diff --git a/arch/powerpc/perf/callchain.h b/arch/powerpc/perf/callchain.h
> index 7a2cb9e1181a..7540bb71cb60 100644
> --- a/arch/powerpc/perf/callchain.h
> +++ b/arch/powerpc/perf/callchain.h
> @@ -2,7 +2,7 @@
>   #ifndef _POWERPC_PERF_CALLCHAIN_H
>   #define _POWERPC_PERF_CALLCHAIN_H
>   
> -int read_user_stack_slow(void __user *ptr, void *buf, int nb);
> +int read_user_stack_slow(const void __user *ptr, void *buf, int nb);

Does the constification of ptr has to be in this patch ?
Wouldn't it be better to have it as a separate patch ?

>   void perf_callchain_user_64(struct perf_callchain_entry_ctx *entry,
>   			    struct pt_regs *regs);
>   void perf_callchain_user_32(struct perf_callchain_entry_ctx *entry,
> @@ -16,4 +16,26 @@ static inline bool invalid_user_sp(unsigned long sp)
>   	return (!sp || (sp & mask) || (sp > top));
>   }
>   
> +/*
> + * 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 inline int __read_user_stack(const void __user *ptr, void *ret,
> +				    size_t size)
> +{
> +	int rc;
> +
> +	if ((unsigned long)ptr > TASK_SIZE - size ||
> +			((unsigned long)ptr & (size - 1)))
> +		return -EFAULT;
> +	rc = probe_user_read(ret, ptr, size);
> +
> +	if (rc && IS_ENABLED(CONFIG_PPC64))

gcc is probably smart enough to deal with it efficiently, but it would
be more correct to test rc after checking CONFIG_PPC64.

> +		return read_user_stack_slow(ptr, ret, size);
> +
> +	return rc;
> +}
> +
>   #endif /* _POWERPC_PERF_CALLCHAIN_H */
> diff --git a/arch/powerpc/perf/callchain_32.c b/arch/powerpc/perf/callchain_32.c
> index 8aa951003141..1b4621f177e8 100644
> --- a/arch/powerpc/perf/callchain_32.c
> +++ b/arch/powerpc/perf/callchain_32.c
> @@ -31,26 +31,9 @@
>   
>   #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.
> - */
> -static int read_user_stack_32(unsigned int __user *ptr, unsigned int *ret)
> +static int read_user_stack_32(const 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;
> +	return __read_user_stack(ptr, ret, sizeof(*ret);
>   }
>   
>   /*
> diff --git a/arch/powerpc/perf/callchain_64.c b/arch/powerpc/perf/callchain_64.c
> index df1ffd8b20f2..55bbc25a54ed 100644
> --- a/arch/powerpc/perf/callchain_64.c
> +++ b/arch/powerpc/perf/callchain_64.c
> @@ -24,7 +24,7 @@
>    * interrupt context, so if the access faults, we read the page tables
>    * to find which page (if any) is mapped and access it directly.
>    */
> -int read_user_stack_slow(void __user *ptr, void *buf, int nb)
> +int read_user_stack_slow(const void __user *ptr, void *buf, int nb)
>   {
>   	int ret = -EFAULT;
>   	pgd_t *pgdir;
> @@ -65,16 +65,10 @@ 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_64(const unsigned long __user *ptr,
> +			      unsigned long *ret)
>   {
> -	if ((unsigned long)ptr > TASK_SIZE - sizeof(unsigned long) ||
> -	    ((unsigned long)ptr & 7))
> -		return -EFAULT;
> -
> -	if (!probe_user_read(ret, ptr, sizeof(*ret)))
> -		return 0;
> -
> -	return read_user_stack_slow(ptr, ret, 8);
> +	return __read_user_stack(ptr, ret, sizeof(*ret));
>   }
>   
>   /*
> 

Christophe

  reply	other threads:[~2020-04-07  5:21 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200225173541.1549955-1-npiggin@gmail.com>
2020-03-19 12:19 ` [PATCH v11 0/8] Disable compat cruft on ppc64le v11 Michal Suchanek
2020-03-19 12:19   ` [PATCH v11 1/8] powerpc: Add back __ARCH_WANT_SYS_LLSEEK macro Michal Suchanek
2020-03-19 12:19   ` [PATCH v11 2/8] powerpc: move common register copy functions from signal_32.c to signal.c Michal Suchanek
2020-03-19 12:19   ` [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32 Michal Suchanek
2020-03-24  8:48     ` Nicholas Piggin
2020-03-24 19:38       ` Michal Suchánek
2020-04-03  7:13         ` Nicholas Piggin
2020-04-03 10:52           ` Michal Suchánek
2020-04-03 11:26             ` Nicholas Piggin
2020-04-03 11:51               ` Michal Suchánek
2020-04-06 20:52           ` Michal Suchánek
2020-04-06 21:00           ` [PATCH] powerpcs: perf: consolidate perf_callchain_user_64 and perf_callchain_user_32 Michal Suchanek
2020-04-07  5:21             ` Christophe Leroy [this message]
2020-04-09 11:22               ` Michal Suchánek
2020-03-19 12:19   ` [PATCH v11 4/8] powerpc/perf: consolidate valid_user_sp Michal Suchanek
2020-03-19 12:19   ` [PATCH v11 5/8] powerpc/64: make buildable without CONFIG_COMPAT Michal Suchanek
2020-03-24  8:54     ` Nicholas Piggin
2020-03-24 19:30       ` Michal Suchánek
2020-04-03  7:16         ` Nicholas Piggin
2020-03-19 12:19   ` [PATCH v11 6/8] powerpc/64: Make COMPAT user-selectable disabled on littleendian by default Michal Suchanek
2020-03-19 12:19   ` [PATCH v11 7/8] powerpc/perf: split callchain.c by bitness Michal Suchanek
2020-03-19 12:19   ` [PATCH v11 8/8] MAINTAINERS: perf: Add pattern that matches ppc perf to the perf entry Michal Suchanek
2020-03-19 13:37     ` Andy Shevchenko
2020-03-19 14:00       ` Michal Suchánek
2020-03-19 14:26         ` Andy Shevchenko
2020-03-19 17:03     ` Joe Perches
2020-03-19 12:36   ` [PATCH v11 0/8] Disable compat cruft on ppc64le v11 Christophe Leroy
2020-03-19 14:01     ` Michal Suchánek
2020-04-03  7:25   ` Nicholas Piggin
2020-04-03  7:26     ` Christophe Leroy
2020-04-03  9:43       ` Nicholas Piggin
2020-04-05  0:40         ` Michael Ellerman
2020-03-20 10:20 ` [PATCH v12 0/8] Disable compat cruft on ppc64le v12 Michal Suchanek
2020-03-20 10:20   ` [PATCH v12 1/8] powerpc: Add back __ARCH_WANT_SYS_LLSEEK macro Michal Suchanek
2020-03-20 10:20   ` [PATCH v12 2/8] powerpc: move common register copy functions from signal_32.c to signal.c Michal Suchanek
2020-03-20 10:20   ` [PATCH v12 3/8] powerpc/perf: consolidate read_user_stack_32 Michal Suchanek
2020-03-20 10:20   ` [PATCH v12 4/8] powerpc/perf: consolidate valid_user_sp -> invalid_user_sp Michal Suchanek
2020-03-20 10:20   ` [PATCH v12 5/8] powerpc/64: make buildable without CONFIG_COMPAT Michal Suchanek
2020-04-07  5:50     ` Christophe Leroy
2020-04-07  9:57       ` Michal Suchánek
2020-03-20 10:20   ` [PATCH v12 6/8] powerpc/64: Make COMPAT user-selectable disabled on littleendian by default Michal Suchanek
2020-03-20 10:20   ` [PATCH v12 7/8] powerpc/perf: split callchain.c by bitness Michal Suchanek
2020-03-20 10:20   ` [PATCH v12 8/8] MAINTAINERS: perf: Add pattern that matches ppc perf to the perf entry Michal Suchanek
2020-03-20 10:33     ` Andy Shevchenko
2020-03-20 11:23       ` Michal Suchánek
2020-03-20 12:42         ` Andy Shevchenko
2020-03-20 14:42           ` Joe Perches
2020-03-20 16:28             ` Michal Suchánek
2020-03-20 16:31             ` Andy Shevchenko
2020-03-20 16:42               ` Michal Suchánek
2020-03-20 16:47                 ` Andy Shevchenko
2020-03-20 21:36               ` Joe Perches

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