Re: [PATCH 2/2] alpha/ptrace: Add missing switch_stack frames
From: Eric W. Biederman <hidden>
Date: 2021-06-16 20:47:40
Also in:
linux-alpha, linux-arch, 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 · Eric W. Biederman <hidden>
- 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 · [PATCH 2/2] alpha/ptrace: Add missing switch_stack frames · Eric W. Biederman <hidden>
Al Viro [off-list ref] writes:
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.
Fork already saves the registers, all I did was restore them. Which
makes a debugger that modifies them in
PTRACE_EVENT_{FORK,VFORK,CLONE,VFORK_DONE} work.
quoted
+allregs exit +allregs exit_groupDetails, please - what exactly makes exit(2) different from e.g. open(2)?
PTRACE_EVENT_EXIT. Eric