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linux(4): Simplify %r10 restoring on amd64

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Restore %r10 at system call entry to avoid doing this multiply times.

Differential Revision:	https://reviews.freebsd.org/D40154
MFC after:		1 month
This commit is contained in:
Dmitry Chagin 2023-05-28 17:06:23 +03:00
parent a463dd8108
commit 185bd9fa30
2 changed files with 3 additions and 9 deletions
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6
sys/amd64/linux/linux_machdep.c
View file

@ -350,12 +350,6 @@ linux_ptrace_getregs_machdep(struct thread *td, pid_t pid,
linux_msg(td, "PT_LWPINFO failed with error %d", error);
return (error);
}
if ((lwpinfo.pl_flags & PL_FLAG_SCE) != 0) {
/*
* Undo the mangling done in exception.S:fast_syscall_common().
*/
l_regset->r10 = l_regset->rcx;
}
if ((lwpinfo.pl_flags & (PL_FLAG_SCE | PL_FLAG_SCX)) != 0) {
/*
* In Linux, the syscall number - passed to the syscall

6
sys/amd64/linux/linux_sysvec.c
View file

@ -167,6 +167,9 @@ linux_fetch_syscall_args(struct thread *td)
else
sa->callp = &p->p_sysent->sv_table[sa->code];
/* Restore r10 earlier to avoid doing this multiply times. */
frame->tf_r10 = frame->tf_rcx;
td->td_retval[0] = 0;
return (0);
}
@ -181,7 +184,6 @@ linux_set_syscall_retval(struct thread *td, int error)
switch (error) {
case 0:
frame->tf_rax = td->td_retval[0];
frame->tf_r10 = frame->tf_rcx;
break;
case ERESTART:
@ -192,7 +194,6 @@ linux_set_syscall_retval(struct thread *td, int error)
*
*/
frame->tf_rip -= frame->tf_err;
frame->tf_r10 = frame->tf_rcx;
break;
case EJUSTRETURN:
@ -200,7 +201,6 @@ linux_set_syscall_retval(struct thread *td, int error)
default:
frame->tf_rax = bsd_to_linux_errno(error);
frame->tf_r10 = frame->tf_rcx;
break;
}