Author: jhb
Date: Mon Apr 27 04:47:02 2020
New Revision: 360363
URL: https://svnweb.freebsd.org/changeset/base/360363
Log:
MFC 350012: Always set td_errno to the error value of a system call.
Early errors prior to a system call did not set td_errno. This commit
sets td_errno for all errors during syscallenter(). As a result,
syscallret() can now always use td_errno without checking TDP_NERRNO.
Compared to the original commit, this change preserves the ABI of
struct thread and instead adds explicit zero'ing of td_errno.
Modified:
stable/12/sys/compat/linux/linux_fork.c
stable/12/sys/kern/kern_fork.c
stable/12/sys/kern/kern_kthread.c
stable/12/sys/kern/kern_thr.c
stable/12/sys/kern/subr_syscall.c
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/compat/linux/linux_fork.c
==============================================================================
--- stable/12/sys/compat/linux/linux_fork.c Mon Apr 27 03:57:17 2020
(r360362)
+++ stable/12/sys/compat/linux/linux_fork.c Mon Apr 27 04:47:02 2020
(r360363)
@@ -310,6 +310,7 @@ linux_clone_thread(struct thread *td, struct linux_clo
bzero(&newtd->td_startzero,
__rangeof(struct thread, td_startzero, td_endzero));
newtd->td_pflags2 = 0;
+ newtd->td_errno = 0;
bcopy(&td->td_startcopy, &newtd->td_startcopy,
__rangeof(struct thread, td_startcopy, td_endcopy));
Modified: stable/12/sys/kern/kern_fork.c
==============================================================================
--- stable/12/sys/kern/kern_fork.c Mon Apr 27 03:57:17 2020
(r360362)
+++ stable/12/sys/kern/kern_fork.c Mon Apr 27 04:47:02 2020
(r360363)
@@ -490,6 +490,7 @@ do_fork(struct thread *td, struct fork_req *fr, struct
bzero(&td2->td_startzero,
__rangeof(struct thread, td_startzero, td_endzero));
td2->td_pflags2 = 0;
+ td2->td_errno = 0;
bcopy(&td->td_startcopy, &td2->td_startcopy,
__rangeof(struct thread, td_startcopy, td_endcopy));
Modified: stable/12/sys/kern/kern_kthread.c
==============================================================================
--- stable/12/sys/kern/kern_kthread.c Mon Apr 27 03:57:17 2020
(r360362)
+++ stable/12/sys/kern/kern_kthread.c Mon Apr 27 04:47:02 2020
(r360363)
@@ -284,6 +284,7 @@ kthread_add(void (*func)(void *), void *arg, struct pr
bzero(&newtd->td_startzero,
__rangeof(struct thread, td_startzero, td_endzero));
newtd->td_pflags2 = 0;
+ newtd->td_errno = 0;
bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
__rangeof(struct thread, td_startcopy, td_endcopy));
Modified: stable/12/sys/kern/kern_thr.c
==============================================================================
--- stable/12/sys/kern/kern_thr.c Mon Apr 27 03:57:17 2020
(r360362)
+++ stable/12/sys/kern/kern_thr.c Mon Apr 27 04:47:02 2020
(r360363)
@@ -236,6 +236,7 @@ thread_create(struct thread *td, struct rtprio *rtp,
bzero(&newtd->td_startzero,
__rangeof(struct thread, td_startzero, td_endzero));
newtd->td_pflags2 = 0;
+ newtd->td_errno = 0;
bcopy(&td->td_startcopy, &newtd->td_startcopy,
__rangeof(struct thread, td_startcopy, td_endcopy));
newtd->td_proc = td->td_proc;
Modified: stable/12/sys/kern/subr_syscall.c
==============================================================================
--- stable/12/sys/kern/subr_syscall.c Mon Apr 27 03:57:17 2020
(r360362)
+++ stable/12/sys/kern/subr_syscall.c Mon Apr 27 04:47:02 2020
(r360363)
@@ -85,8 +85,10 @@ syscallenter(struct thread *td)
(uintptr_t)td, "pid:%d", td->td_proc->p_pid, "arg0:%p", sa->args[0],
"arg1:%p", sa->args[1], "arg2:%p", sa->args[2]);
- if (error != 0)
+ if (error != 0) {
+ td->td_errno = error;
goto retval;
+ }
STOPEVENT(p, S_SCE, sa->narg);
if ((p->p_flag & P_TRACED) != 0) {
@@ -105,8 +107,10 @@ syscallenter(struct thread *td)
if (KTRPOINT(td, KTR_SYSCALL))
ktrsyscall(sa->code, sa->narg, sa->args);
#endif
- if (error != 0)
+ if (error != 0) {
+ td->td_errno = error;
goto retval;
+ }
}
#ifdef CAPABILITY_MODE
@@ -116,14 +120,16 @@ syscallenter(struct thread *td)
*/
if (IN_CAPABILITY_MODE(td) &&
!(sa->callp->sy_flags & SYF_CAPENABLED)) {
- error = ECAPMODE;
+ td->td_errno = error = ECAPMODE;
goto retval;
}
#endif
error = syscall_thread_enter(td, sa->callp);
- if (error != 0)
+ if (error != 0) {
+ td->td_errno = error;
goto retval;
+ }
#ifdef KDTRACE_HOOKS
/* Give the syscall:::entry DTrace probe a chance to fire. */
@@ -131,6 +137,9 @@ syscallenter(struct thread *td)
(*systrace_probe_func)(sa, SYSTRACE_ENTRY, 0);
#endif
+ /* Let system calls set td_errno directly. */
+ td->td_pflags &= ~TDP_NERRNO;
+
AUDIT_SYSCALL_ENTER(sa->code, td);
error = (sa->callp->sy_call)(td, sa->args);
AUDIT_SYSCALL_EXIT(error, td);
@@ -162,12 +171,12 @@ syscallenter(struct thread *td)
}
static inline void
-syscallret(struct thread *td, int error)
+syscallret(struct thread *td, int error __unused)
{
struct proc *p, *p2;
struct syscall_args *sa;
ksiginfo_t ksi;
- int traced, error1;
+ int traced;
KASSERT((td->td_pflags & TDP_FORKING) == 0,
("fork() did not clear TDP_FORKING upon completion"));
@@ -176,12 +185,10 @@ syscallret(struct thread *td, int error)
sa = &td->td_sa;
if ((trap_enotcap || (p->p_flag2 & P2_TRAPCAP) != 0) &&
IN_CAPABILITY_MODE(td)) {
- error1 = (td->td_pflags & TDP_NERRNO) == 0 ? error :
- td->td_errno;
- if (error1 == ENOTCAPABLE || error1 == ECAPMODE) {
+ if (td->td_errno == ENOTCAPABLE || td->td_errno == ECAPMODE) {
ksiginfo_init_trap(&ksi);
ksi.ksi_signo = SIGTRAP;
- ksi.ksi_errno = error1;
+ ksi.ksi_errno = td->td_errno;
ksi.ksi_code = TRAP_CAP;
trapsignal(td, &ksi);
}
@@ -194,11 +201,9 @@ syscallret(struct thread *td, int error)
#ifdef KTRACE
if (KTRPOINT(td, KTR_SYSRET)) {
- ktrsysret(sa->code, (td->td_pflags & TDP_NERRNO) == 0 ?
- error : td->td_errno, td->td_retval[0]);
+ ktrsysret(sa->code, td->td_errno, td->td_retval[0]);
}
#endif
- td->td_pflags &= ~TDP_NERRNO;
if (p->p_flag & P_TRACED) {
traced = 1;
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