From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: linuxppc-dev@lists.ozlabs.org, "Christopher M. Riedl" <cmr@codefail.de>
Subject: Re: [PATCH 8/8] powerpc/signal64: Rewrite rt_sigreturn() to minimise uaccess switches
Date: Fri, 16 Oct 2020 16:07:38 +0200 [thread overview]
Message-ID: <bdc30b81-65bd-1cc0-b31a-61300e8c010a@csgroup.eu> (raw)
In-Reply-To: <20201015150159.28933-9-cmr@codefail.de>
Le 15/10/2020 à 17:01, Christopher M. Riedl a écrit :
> From: Daniel Axtens <dja@axtens.net>
>
> Add uaccess blocks and use the 'unsafe' versions of functions doing user
> access where possible to reduce the number of times uaccess has to be
> opened/closed.
>
> Signed-off-by: Daniel Axtens <dja@axtens.net>
> Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
> ---
> arch/powerpc/kernel/signal_64.c | 23 +++++++++++++++--------
> 1 file changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
> index 3b97e3681a8f..0f4ff7a5bfc1 100644
> --- a/arch/powerpc/kernel/signal_64.c
> +++ b/arch/powerpc/kernel/signal_64.c
> @@ -779,18 +779,22 @@ SYSCALL_DEFINE0(rt_sigreturn)
> */
> regs->msr &= ~MSR_TS_MASK;
>
> - if (__get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR]))
> + if (!user_read_access_begin(uc, sizeof(*uc)))
> goto badframe;
> +
> + unsafe_get_user(msr, &uc->uc_mcontext.gp_regs[PT_MSR], badframe_block);
> +
> if (MSR_TM_ACTIVE(msr)) {
> /* We recheckpoint on return. */
> struct ucontext __user *uc_transact;
>
> /* Trying to start TM on non TM system */
> if (!cpu_has_feature(CPU_FTR_TM))
> - goto badframe;
> + goto badframe_block;
> +
> + unsafe_get_user(uc_transact, &uc->uc_link, badframe_block);
> + user_read_access_end();
user_access_end() only in the if branch ?
>
> - if (__get_user(uc_transact, &uc->uc_link))
> - goto badframe;
> if (restore_tm_sigcontexts(current, &uc->uc_mcontext,
> &uc_transact->uc_mcontext))
> goto badframe;
> @@ -810,12 +814,13 @@ SYSCALL_DEFINE0(rt_sigreturn)
> * causing a TM bad thing.
> */
> current->thread.regs->msr &= ~MSR_TS_MASK;
> +
> +#ifndef CONFIG_PPC_TRANSACTIONAL_MEM
> if (!user_read_access_begin(uc, sizeof(*uc)))
The matching user_read_access_end() is not in the same #ifndef ? That's dirty and hard to follow.
Can you re-organise the code to avoid all those nesting ?
> - return -EFAULT;
> - if (__unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext)) {
> - user_read_access_end();
> goto badframe;
> - }
> +#endif
> + unsafe_restore_sigcontext(current, NULL, 1, &uc->uc_mcontext,
> + badframe_block);
> user_read_access_end();
> }
>
> @@ -825,6 +830,8 @@ SYSCALL_DEFINE0(rt_sigreturn)
> set_thread_flag(TIF_RESTOREALL);
> return 0;
>
> +badframe_block:
> + user_read_access_end();
> badframe:
> signal_fault(current, regs, "rt_sigreturn", uc);
>
>
Christophe
next prev parent reply other threads:[~2020-10-16 14:13 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-15 15:01 [PATCH 0/8] Improve signal performance on PPC64 with KUAP Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 1/8] powerpc/uaccess: Add unsafe_copy_from_user Christopher M. Riedl
2020-10-16 6:54 ` Christoph Hellwig
2020-10-16 13:18 ` Christophe Leroy
2020-10-16 13:17 ` Christophe Leroy
2020-10-20 3:00 ` Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx,fpr}_from_user() Christopher M. Riedl
2020-10-16 13:48 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx, fpr}_from_user() Christophe Leroy
2020-10-20 2:01 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx,fpr}_from_user() Christopher M. Riedl
2021-02-06 16:32 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx, fpr}_from_user() Christophe Leroy
2021-02-06 17:39 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx,fpr}_from_user() Christopher M. Riedl
2021-02-07 10:12 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx, fpr}_from_user() Christophe Leroy
2021-02-08 17:14 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx,fpr}_from_user() Christopher M. Riedl
2021-02-08 17:18 ` [PATCH 2/8] powerpc/signal: Add unsafe_copy_{vsx, fpr}_from_user() Christophe Leroy
2020-10-15 15:01 ` [PATCH 3/8] powerpc: Mark functions called inside uaccess blocks w/ 'notrace' Christopher M. Riedl
2020-10-16 6:56 ` Christoph Hellwig
2020-10-16 9:41 ` Peter Zijlstra
2020-10-20 7:34 ` Michael Ellerman
2020-10-16 7:02 ` Christophe Leroy
2020-10-20 1:59 ` Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 4/8] powerpc/signal64: Replace setup_sigcontext() w/ unsafe_setup_sigcontext() Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 5/8] powerpc/signal64: Replace restore_sigcontext() w/ unsafe_restore_sigcontext() Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 6/8] powerpc/signal64: Replace setup_trampoline() w/ unsafe_setup_trampoline() Christopher M. Riedl
2020-10-16 13:56 ` Christophe Leroy
2020-10-20 2:42 ` Christopher M. Riedl
2020-10-20 5:02 ` Christophe Leroy
2020-10-15 15:01 ` [PATCH 7/8] powerpc/signal64: Rewrite handle_rt_signal64() to minimise uaccess switches Christopher M. Riedl
2020-10-16 14:00 ` Christophe Leroy
2020-10-20 2:44 ` Christopher M. Riedl
2020-10-15 15:01 ` [PATCH 8/8] powerpc/signal64: Rewrite rt_sigreturn() " Christopher M. Riedl
2020-10-16 14:07 ` Christophe Leroy [this message]
2020-10-20 2:45 ` Christopher M. Riedl
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