From: Nicholas Piggin <npiggin@gmail.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Michael Ellerman <mpe@ellerman.id.au>,
msuchanek@suse.de, Paul Mackerras <paulus@samba.org>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v5 19/22] powerpc/syscall: Optimise checks in beginning of system_call_exception()
Date: Tue, 09 Feb 2021 12:06:05 +1000 [thread overview]
Message-ID: <1612836170.502t0sssvi.astroid@bobo.none> (raw)
In-Reply-To: <3e48bb439357c6f72ae4343bf93bd29f0980eeb1.1612796617.git.christophe.leroy@csgroup.eu>
Excerpts from Christophe Leroy's message of February 9, 2021 1:10 am:
> Combine all tests of regs->msr into a single logical one.
Okay by me unless we choose to do the config option and put these all
under it. I think I would prefer that because sometimes the registers
are in a state you can't easily see what the values in the expression
were. In this case it doesn't matter so much because they should be in
regs in the interrupt frame.
Thanks,
Nick
>
> Before the patch:
>
> 0: 81 6a 00 84 lwz r11,132(r10)
> 4: 90 6a 00 88 stw r3,136(r10)
> 8: 69 60 00 02 xori r0,r11,2
> c: 54 00 ff fe rlwinm r0,r0,31,31,31
> 10: 0f 00 00 00 twnei r0,0
> 14: 69 63 40 00 xori r3,r11,16384
> 18: 54 63 97 fe rlwinm r3,r3,18,31,31
> 1c: 0f 03 00 00 twnei r3,0
> 20: 69 6b 80 00 xori r11,r11,32768
> 24: 55 6b 8f fe rlwinm r11,r11,17,31,31
> 28: 0f 0b 00 00 twnei r11,0
>
> After the patch:
>
> 0: 81 6a 00 84 lwz r11,132(r10)
> 4: 90 6a 00 88 stw r3,136(r10)
> 8: 7d 6b 58 f8 not r11,r11
> c: 71 6b c0 02 andi. r11,r11,49154
> 10: 0f 0b 00 00 twnei r11,0
>
> 6 cycles less on powerpc 8xx (328 => 322 cycles).
>
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
> arch/powerpc/kernel/interrupt.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c
> index 55e1aa18cdb9..8c38e8c95be2 100644
> --- a/arch/powerpc/kernel/interrupt.c
> +++ b/arch/powerpc/kernel/interrupt.c
> @@ -28,6 +28,7 @@ notrace long system_call_exception(long r3, long r4, long r5,
> unsigned long r0, struct pt_regs *regs)
> {
> syscall_fn f;
> + unsigned long expected_msr;
>
> regs->orig_gpr3 = r3;
>
> @@ -39,10 +40,13 @@ notrace long system_call_exception(long r3, long r4, long r5,
>
> trace_hardirqs_off(); /* finish reconciling */
>
> + expected_msr = MSR_PR;
> if (!IS_ENABLED(CONFIG_BOOKE) && !IS_ENABLED(CONFIG_40x))
> - BUG_ON(!(regs->msr & MSR_RI));
> - BUG_ON(!(regs->msr & MSR_PR));
> - BUG_ON(arch_irq_disabled_regs(regs));
> + expected_msr |= MSR_RI;
> + if (IS_ENABLED(CONFIG_PPC32))
> + expected_msr |= MSR_EE;
> + BUG_ON((regs->msr & expected_msr) ^ expected_msr);
> + BUG_ON(IS_ENABLED(CONFIG_PPC64) && arch_irq_disabled_regs(regs));
>
> #ifdef CONFIG_PPC_PKEY
> if (mmu_has_feature(MMU_FTR_PKEY)) {
> --
> 2.25.0
>
>
next prev parent reply other threads:[~2021-02-09 2:07 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-08 15:10 [PATCH v5 00/22] powerpc/32: Implement C syscall entry/exit Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 01/22] powerpc/32s: Add missing call to kuep_lock on syscall entry Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 02/22] powerpc/32: Always enable data translation " Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 03/22] powerpc/32: On syscall entry, enable instruction translation at the same time as data Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 04/22] powerpc/32: Reorder instructions to avoid using CTR in syscall entry Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 05/22] powerpc/irq: Add helper to set regs->softe Christophe Leroy
2021-02-09 1:11 ` Nicholas Piggin
2021-02-09 5:57 ` Christophe Leroy
2021-02-09 7:47 ` Nicholas Piggin
2021-02-09 6:18 ` Christophe Leroy
2021-02-09 7:49 ` Nicholas Piggin
2021-03-05 8:54 ` Christophe Leroy
2021-03-08 8:47 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 06/22] powerpc/irq: Rework helpers that manipulate MSR[EE/RI] Christophe Leroy
2021-02-09 1:14 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 07/22] powerpc/irq: Add stub irq_soft_mask_return() for PPC32 Christophe Leroy
2021-02-09 1:19 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 08/22] powerpc/syscall: Rename syscall_64.c into interrupt.c Christophe Leroy
2021-02-09 1:19 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 09/22] powerpc/syscall: Make interrupt.c buildable on PPC32 Christophe Leroy
2021-02-09 1:27 ` Nicholas Piggin
2021-02-09 6:02 ` Christophe Leroy
2021-02-09 7:50 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 10/22] powerpc/syscall: Use is_compat_task() Christophe Leroy
2021-02-09 1:29 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 11/22] powerpc/syscall: Save r3 in regs->orig_r3 Christophe Leroy
2021-02-09 1:29 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 12/22] powerpc/syscall: Change condition to check MSR_RI Christophe Leroy
2021-02-09 1:36 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 13/22] powerpc/32: Always save non volatile GPRs at syscall entry Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 14/22] powerpc/syscall: implement system call entry/exit logic in C for PPC32 Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 15/22] powerpc/32: Remove verification of MSR_PR on syscall in the ASM entry Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 16/22] powerpc/syscall: Avoid stack frame in likely part of system_call_exception() Christophe Leroy
2021-02-09 1:55 ` Nicholas Piggin
2021-02-09 16:13 ` Christophe Leroy
2021-02-10 1:56 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 17/22] powerpc/syscall: Do not check unsupported scv vector on PPC32 Christophe Leroy
2021-02-09 2:00 ` Nicholas Piggin
2021-02-09 6:13 ` Christophe Leroy
2021-02-09 7:56 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 18/22] powerpc/syscall: Remove FULL_REGS verification in system_call_exception Christophe Leroy
2021-02-09 2:02 ` Nicholas Piggin
2021-02-09 14:31 ` Christophe Leroy
2021-02-10 1:57 ` Nicholas Piggin
2021-02-08 15:10 ` [PATCH v5 19/22] powerpc/syscall: Optimise checks in beginning of system_call_exception() Christophe Leroy
2021-02-09 2:06 ` Nicholas Piggin [this message]
2021-02-09 14:32 ` Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 20/22] powerpc/syscall: Avoid storing 'current' in another pointer Christophe Leroy
2021-02-09 2:36 ` Nicholas Piggin
2021-02-09 13:50 ` Segher Boessenkool
2021-02-09 14:31 ` David Laight
2021-02-09 17:03 ` Christophe Leroy
2021-02-09 17:16 ` David Laight
2021-02-10 2:00 ` Nicholas Piggin
2021-02-10 8:45 ` Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 21/22] powerpc/32: Remove the counter in global_dbcr0 Christophe Leroy
2021-02-08 15:10 ` [PATCH v5 22/22] powerpc/32: Handle bookE debugging in C in syscall entry/exit Christophe Leroy
2021-02-09 1:03 ` [PATCH v5 00/22] powerpc/32: Implement C " Nicholas Piggin
2021-02-12 0:19 ` Michael Ellerman
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