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From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org, Michal Suchanek <msuchanek@suse.de>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Allison Randal <allison@lohutok.net>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Thiago Jung Bauermann <bauerman@linux.ibm.com>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Claudio Carvalho <cclaudio@linux.ibm.com>,
	Christophe Leroy <christophe.leroy@c-s.fr>,
	"David S. Miller" <davem@davemloft.net>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Eric Richter <erichte@linux.ibm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Gustavo Luiz Duarte <gustavold@linux.ibm.com>,
	Hari Bathini <hbathini@linux.ibm.com>,
	Jordan Niethe <jniethe5@gmail.com>, Jiri Olsa <jolsa@redhat.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	Mark Rutland <mark.rutland@arm.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
	Michael Neuling <mikey@neuling.org>,
	Ingo Molnar <mingo@redhat.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Namhyung Kim <namhyung@kernel.org>,
	Nayna Jain <nayna@linux.ibm.com>,
	Paul Mackerras <paulus@samba.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Rob Herring <robh@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32
Date: Tue, 24 Mar 2020 18:48:20 +1000	[thread overview]
Message-ID: <1585039473.da4762n2s0.astroid@bobo.none> (raw)
In-Reply-To: <184347595442b4ca664613008a09e8cea7188c36.1584620202.git.msuchanek@suse.de>

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 <msuchanek@suse.de>
> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
> 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 : 0x100000000UL) - 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
> 
> 

  reply	other threads:[~2020-03-24  8:48 UTC|newest]

Thread overview: 53+ 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 [this message]
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
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
2020-03-19 11:52 [PATCH v11 0/8] Disable compat cruft on ppc64le v11 Michal Suchanek
2020-03-19 11:52 ` [PATCH v11 3/8] powerpc/perf: consolidate read_user_stack_32 Michal Suchanek

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