From: Al Viro <viro@ZenIV.linux.org.uk>
To: Ley Foon Tan <lftan@altera.com>
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-doc@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
lftan.linux@gmail.com, cltang@codesourcery.com
Subject: Re: [PATCH v4 04/29] nios2: Exception handling
Date: Wed, 8 Oct 2014 23:27:22 +0100 [thread overview]
Message-ID: <20141008222722.GJ7996@ZenIV.linux.org.uk> (raw)
In-Reply-To: <1412760595-3935-5-git-send-email-lftan@altera.com>
> +Lsignal_return:
> + ANDI32 r1, r10, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME
> + beq r1, r0, restore_all
> + mov r4, sp /* pt_regs */
> + SAVE_SWITCH_STACK
> + call do_notify_resume
> + beq r2, r0, no_work_pending
> + RESTORE_SWITCH_STACK
> + /* prepare restart syscall here without leaving kernel */
> + ldw r2, PT_R2(sp) /* reload syscall number in r2 */
> + ldw r4, PT_R4(sp) /* reload syscall arguments r4-r9 */
> + ldw r5, PT_R5(sp)
> + ldw r6, PT_R6(sp)
> + ldw r7, PT_R7(sp)
> + ldw r8, PT_R8(sp)
> + ldw r9, PT_R9(sp)
> + br local_restart /* restart syscall */
> +
> +no_work_pending:
> + RESTORE_SWITCH_STACK
> + br restore_all
Umm... Branch to no_work_pending will be usuall taken. How well does
branch predictor on that processor cope with such things?
Another thing is the point Richard made - multiple pending signals need to be
handled. IOW, that should be a branch to ret_from_exception, not restore_all.
next prev parent reply other threads:[~2014-10-08 22:27 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-08 9:29 [PATCH v4 00/29] nios2 Linux kernel port Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 01/29] asm-generic: add generic futex for !CONFIG_SMP Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 02/29] nios2: Assembly macros and definitions Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 03/29] nios2: Kernel booting and initialization Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 04/29] nios2: Exception handling Ley Foon Tan
2014-10-08 22:27 ` Al Viro [this message]
2014-10-09 8:31 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 05/29] nios2: Traps exception handling Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 06/29] nios2: Memory management Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 07/29] nios2: I/O Mapping Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 08/29] nios2: MMU Fault handling Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 09/29] nios2: Page table management Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 10/29] nios2: Process management Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 11/29] nios2: Cache handling Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 12/29] nios2: TLB handling Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 13/29] nios2: Interrupt handling Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 10:59 ` Thomas Gleixner
2014-10-08 10:59 ` Thomas Gleixner
2014-10-08 9:29 ` [PATCH v4 14/29] nios2: DMA mapping API Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 15/29] Add ELF machine define for Nios2 Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 16/29] nios2: ELF definitions Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 17/29] nios2: System calls handling Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-09 7:47 ` Tobias Klauser
2014-10-09 7:47 ` Tobias Klauser
2014-10-09 8:38 ` Ley Foon Tan
2014-10-09 8:38 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 18/29] nios2: Signal handling support Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 11:29 ` Richard Weinberger
2014-10-08 11:29 ` Richard Weinberger
2014-10-09 8:33 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 19/29] nios2: Library functions Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 20/29] nios2: Device tree support Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 21/29] nios2: Time keeping Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 10:44 ` Thomas Gleixner
2014-10-08 15:17 ` Arnd Bergmann
2014-10-08 15:17 ` Arnd Bergmann
2014-10-08 15:20 ` Thomas Gleixner
2014-10-08 15:20 ` Thomas Gleixner
2014-10-08 15:39 ` Arnd Bergmann
2014-10-08 15:39 ` Arnd Bergmann
2014-10-08 16:19 ` Thomas Gleixner
2014-10-08 16:19 ` Thomas Gleixner
2014-10-09 11:57 ` Arnd Bergmann
2014-10-09 11:57 ` Arnd Bergmann
2014-10-09 9:00 ` Ley Foon Tan
2014-10-09 9:00 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 22/29] nios2: Cpuinfo handling Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 23/29] nios2: Miscellaneous header files Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 24/29] nios2: Nios2 registers Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 25/29] nios2: Module support Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 26/29] nios2: ptrace support Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 27/29] MAINTAINERS: Add nios2 maintainer Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 28/29] Documentation: Add documentation for Nios2 architecture Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
2014-10-08 9:29 ` [PATCH v4 29/29] nios2: Build infrastructure Ley Foon Tan
2014-10-08 9:29 ` Ley Foon Tan
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