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Re: [PATCH v6 02/16] linux-user/host/ppc64: Use r11 for signal_pending a
From: |
Peter Maydell |
Subject: |
Re: [PATCH v6 02/16] linux-user/host/ppc64: Use r11 for signal_pending address |
Date: |
Mon, 29 Nov 2021 11:01:29 +0000 |
On Tue, 23 Nov 2021 at 17:40, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> We don't need a register that can live across the syscall;
> we only need a register that can live until the syscall.
What about the case where:
* we execute the sc instruction (r11 trashed)
* the syscall is one that from the host kernel point of
view is restartable
* the kernel arranges to restart the syscall by rewinding the
PC to point to the start of the 'sc' instruction
* our rewind_if_in_safe_syscall() rewinds PC further to
point at safe_syscall_start
* we want to use r11 again, but it was trashed in step 1
?
Put another way, this patch is effectively a revert of
commit 5d9f3ea081721, which was a fix to an observed bug.
-- PMM
- [PATCH for-7.0 v6 00/16] linux-user: simplify safe signal handling, Richard Henderson, 2021/11/23
- [PATCH v6 02/16] linux-user/host/ppc64: Use r11 for signal_pending address, Richard Henderson, 2021/11/23
- Re: [PATCH v6 02/16] linux-user/host/ppc64: Use r11 for signal_pending address,
Peter Maydell <=
- [PATCH v6 01/16] linux-user: Untabify all safe-syscall.inc.S, Richard Henderson, 2021/11/23
- [PATCH v6 03/16] linux-user: Move syscall error detection into safe_syscall_base, Richard Henderson, 2021/11/23
- [PATCH v6 04/16] linux-user/host/mips: Add safe-syscall.inc.S, Richard Henderson, 2021/11/23
- [PATCH v6 05/16] linux-user/host/sparc64: Add safe-syscall.inc.S, Richard Henderson, 2021/11/23