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Always set td_errno to the error value of a system call.

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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.

Reviewed by:	kib
MFC after:	1 month
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D20898
This commit is contained in:
John Baldwin 2019-07-15 21:16:01 +00:00
parent 8a3cfbff92
commit 1af9474b26
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=350012
3 changed files with 21 additions and 17 deletions
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4
sys/kern/kern_thread.c
View File

@ -84,7 +84,7 @@ _Static_assert(offsetof(struct thread, td_pflags) == 0x104,
"struct thread KBI td_pflags");
_Static_assert(offsetof(struct thread, td_frame) == 0x478,
"struct thread KBI td_frame");
_Static_assert(offsetof(struct thread, td_emuldata) == 0x548,
_Static_assert(offsetof(struct thread, td_emuldata) == 0x540,
"struct thread KBI td_emuldata");
_Static_assert(offsetof(struct proc, p_flag) == 0xb0,
"struct proc KBI p_flag");
@ -102,7 +102,7 @@ _Static_assert(offsetof(struct thread, td_flags) == 0x98,
"struct thread KBI td_flags");
_Static_assert(offsetof(struct thread, td_pflags) == 0xa0,
"struct thread KBI td_pflags");
_Static_assert(offsetof(struct thread, td_frame) == 0x2ec,
_Static_assert(offsetof(struct thread, td_frame) == 0x2f0,
"struct thread KBI td_frame");
_Static_assert(offsetof(struct thread, td_emuldata) == 0x338,
"struct thread KBI td_emuldata");

31
sys/kern/subr_syscall.c
View File

@ -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;
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;

3
sys/sys/proc.h
View File

@ -303,6 +303,7 @@ struct thread {
void *td_su; /* (k) FFS SU private */
sbintime_t td_sleeptimo; /* (t) Sleep timeout. */
int td_rtcgen; /* (s) rtc_generation of abs. sleep */
int td_errno; /* (k) Error from last syscall. */
size_t td_vslock_sz; /* (k) amount of vslock-ed space */
struct kcov_info *td_kcov_info; /* (*) Kernel code coverage data */
#define td_endzero td_sigmask
@ -353,8 +354,6 @@ struct thread {
struct kaudit_record *td_ar; /* (k) Active audit record, if any. */
struct lpohead td_lprof[2]; /* (a) lock profiling objects. */
struct kdtrace_thread *td_dtrace; /* (*) DTrace-specific data. */
int td_errno; /* Error returned by last syscall. */
/* LP64 hole */
struct vnet *td_vnet; /* (k) Effective vnet. */
const char *td_vnet_lpush; /* (k) Debugging vnet push / pop. */
struct trapframe *td_intr_frame;/* (k) Frame of the current irq */