Re: [PATCH 2/2] alpha/ptrace: Add missing switch_stack frames
From: Al Viro <viro@zeniv.linux.org.uk>
Date: 2021-06-16 20:29:06
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linux-arch, linux-m68k, lkml
Possibly related (same subject, not in this thread)
- 2021-06-16 · Re: [PATCH 2/2] alpha/ptrace: Add missing switch_stack frames · Al Viro <viro@zeniv.linux.org.uk>
- 2021-06-16 · Re: [PATCH 2/2] alpha/ptrace: Add missing switch_stack frames · Al Viro <viro@zeniv.linux.org.uk>
- 2021-06-16 · Re: [PATCH 2/2] alpha/ptrace: Add missing switch_stack frames · Eric W. Biederman <hidden>
- 2021-06-16 · Re: [PATCH 2/2] alpha/ptrace: Add missing switch_stack frames · Eric W. Biederman <hidden>
On Wed, Jun 16, 2021 at 08:25:35PM +0000, Al Viro wrote:
On Wed, Jun 16, 2021 at 01:32:50PM -0500, Eric W. Biederman wrote:quoted
-.macro fork_like name +.macro allregs name .align 4 .globl alpha_\name .ent alpha_\name + .cfi_startproc alpha_\name: .prologue 0 - bsr $1, do_switch_stack + SAVE_SWITCH_STACK jsr $26, sys_\name - ldq $26, 56($sp) - lda $sp, SWITCH_STACK_SIZE($sp) + RESTORE_SWITCH_STACKNo. You've just added one hell of an overhead to fork(2), for no reason whatsoever. sys_fork() et.al. does *NOT* modify the callee-saved registers; it's plain C. So this change is complete BS.quoted
+allregs exit +allregs exit_groupDetails, please - what exactly makes exit(2) different from e.g. open(2)?
Ah... PTRACE_EVENT_EXIT garbage, fortunately having no counterparts in case of open(2)... Still, WTF would you want to restore callee-saved registers for in case of exit(2)?