Revert "MFC r319873:"

This reverts commit 5dad0dd804a33b8a372d49fa342b24c67b1c2fb3.

27 files changed, 82 insertions, 123 deletions

diff --git a/sys/amd64/amd64/trap.c b/sys/amd64/amd64/trap.c
index d3adf65..e779ef2 100644
--- a/sys/amd64/amd64/trap.c
+++ b/sys/amd64/amd64/trap.c
@@ -829,18 +829,16 @@ dblfault_handler(struct trapframe *frame)
 }
 
 int
-cpu_fetch_syscall_args(struct thread *td)
+cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
 	struct trapframe *frame;
 	register_t *argp;
-	struct syscall_args *sa;
 	caddr_t params;
 	int reg, regcnt, error;
 
 	p = td->td_proc;
 	frame = td->td_frame;
-	sa = &td->td_sa;
 	reg = 0;
 	regcnt = 6;
 
@@ -891,6 +889,7 @@ cpu_fetch_syscall_args(struct thread *td)
 void
 amd64_syscall(struct thread *td, int traced)
 {
+	struct syscall_args sa;
 	int error;
 	ksiginfo_t ksi;
 
@@ -900,7 +899,7 @@ amd64_syscall(struct thread *td, int traced)
 		/* NOT REACHED */
 	}
 #endif
-	error = syscallenter(td);
+	error = syscallenter(td, &sa);
 
 	/*
 	 * Traced syscall.
@@ -916,16 +915,15 @@ amd64_syscall(struct thread *td, int traced)
 
 	KASSERT(PCB_USER_FPU(td->td_pcb),
 	    ("System call %s returning with kernel FPU ctx leaked",
-	     syscallname(td->td_proc, td->td_sa.code)));
+	     syscallname(td->td_proc, sa.code)));
 	KASSERT(td->td_pcb->pcb_save == get_pcb_user_save_td(td),
 	    ("System call %s returning with mangled pcb_save",
-	     syscallname(td->td_proc, td->td_sa.code)));
+	     syscallname(td->td_proc, sa.code)));
 	KASSERT(td->td_md.md_invl_gen.gen == 0,
 	    ("System call %s returning with leaked invl_gen %lu",
-	    syscallname(td->td_proc, td->td_sa.code),
-	    td->td_md.md_invl_gen.gen));
+	    syscallname(td->td_proc, sa.code), td->td_md.md_invl_gen.gen));
 
-	syscallret(td, error);
+	syscallret(td, error, &sa);
 
 	/*
 	 * If the user-supplied value of %rip is not a canonical
diff --git a/sys/amd64/cloudabi32/cloudabi32_sysvec.c b/sys/amd64/cloudabi32/cloudabi32_sysvec.c
index d5dd58c..abede1a 100644
--- a/sys/amd64/cloudabi32/cloudabi32_sysvec.c
+++ b/sys/amd64/cloudabi32/cloudabi32_sysvec.c
@@ -90,15 +90,11 @@ cloudabi32_proc_setregs(struct thread *td, struct image_params *imgp,
 }
 
 static int
-cloudabi32_fetch_syscall_args(struct thread *td)
+cloudabi32_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
-	struct trapframe *frame;
-	struct syscall_args *sa;
+	struct trapframe *frame = td->td_frame;
 	int error;
 
-	frame = td->td_frame;
-	sa = &td->td_sa;
-
 	/* Obtain system call number. */
 	sa->code = frame->tf_rax;
 	if (sa->code >= CLOUDABI32_SYS_MAXSYSCALL)
diff --git a/sys/amd64/cloudabi64/cloudabi64_sysvec.c b/sys/amd64/cloudabi64/cloudabi64_sysvec.c
index 679888b..84f0cb3 100644
--- a/sys/amd64/cloudabi64/cloudabi64_sysvec.c
+++ b/sys/amd64/cloudabi64/cloudabi64_sysvec.c
@@ -87,13 +87,9 @@ cloudabi64_proc_setregs(struct thread *td, struct image_params *imgp,
 }
 
 static int
-cloudabi64_fetch_syscall_args(struct thread *td)
+cloudabi64_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
-	struct trapframe *frame;
-	struct syscall_args *sa;
-
-	frame = td->td_frame;
-	sa = &td->td_sa;
+	struct trapframe *frame = td->td_frame;
 
 	/* Obtain system call number. */
 	sa->code = frame->tf_rax;
diff --git a/sys/amd64/ia32/ia32_syscall.c b/sys/amd64/ia32/ia32_syscall.c
index c07b38c..6e96edd 100644
--- a/sys/amd64/ia32/ia32_syscall.c
+++ b/sys/amd64/ia32/ia32_syscall.c
@@ -105,18 +105,16 @@ ia32_set_syscall_retval(struct thread *td, int error)
 }
 
 int
-ia32_fetch_syscall_args(struct thread *td)
+ia32_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
 	struct trapframe *frame;
-	struct syscall_args *sa;
 	caddr_t params;
 	u_int32_t args[8], tmp;
 	int error, i;
 
 	p = td->td_proc;
 	frame = td->td_frame;
-	sa = &td->td_sa;
 
 	params = (caddr_t)frame->tf_rsp + sizeof(u_int32_t);
 	sa->code = frame->tf_rax;
@@ -177,6 +175,7 @@ void
 ia32_syscall(struct trapframe *frame)
 {
 	struct thread *td;
+	struct syscall_args sa;
 	register_t orig_tf_rflags;
 	int error;
 	ksiginfo_t ksi;
@@ -185,7 +184,7 @@ ia32_syscall(struct trapframe *frame)
 	td = curthread;
 	td->td_frame = frame;
 
-	error = syscallenter(td);
+	error = syscallenter(td, &sa);
 
 	/*
 	 * Traced syscall.
@@ -199,7 +198,7 @@ ia32_syscall(struct trapframe *frame)
 		trapsignal(td, &ksi);
 	}
 
-	syscallret(td, error);
+	syscallret(td, error, &sa);
 }
 
 static void
diff --git a/sys/amd64/linux/linux_sysvec.c b/sys/amd64/linux/linux_sysvec.c
index f77c2c9..6e12d41 100644
--- a/sys/amd64/linux/linux_sysvec.c
+++ b/sys/amd64/linux/linux_sysvec.c
@@ -126,7 +126,7 @@ static boolean_t linux_trans_osrel(const Elf_Note *note, int32_t *osrel);
 static void	linux_vdso_install(void *param);
 static void	linux_vdso_deinstall(void *param);
 static void	linux_set_syscall_retval(struct thread *td, int error);
-static int	linux_fetch_syscall_args(struct thread *td);
+static int	linux_fetch_syscall_args(struct thread *td, struct syscall_args *sa);
 static void	linux_exec_setregs(struct thread *td, struct image_params *imgp,
 		    u_long stack);
 static int	linux_vsyscall(struct thread *td);
@@ -217,15 +217,13 @@ translate_traps(int signal, int trap_code)
 }
 
 static int
-linux_fetch_syscall_args(struct thread *td)
+linux_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
 	struct trapframe *frame;
-	struct syscall_args *sa;
 
 	p = td->td_proc;
 	frame = td->td_frame;
-	sa = &td->td_sa;
 
 	sa->args[0] = frame->tf_rdi;
 	sa->args[1] = frame->tf_rsi;
diff --git a/sys/amd64/linux32/linux32_sysvec.c b/sys/amd64/linux32/linux32_sysvec.c
index ea849ba..c264f3a 100644
--- a/sys/amd64/linux32/linux32_sysvec.c
+++ b/sys/amd64/linux32/linux32_sysvec.c
@@ -725,15 +725,13 @@ linux_rt_sigreturn(struct thread *td, struct linux_rt_sigreturn_args *args)
 }
 
 static int
-linux32_fetch_syscall_args(struct thread *td)
+linux32_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
 	struct trapframe *frame;
-	struct syscall_args *sa;
 
 	p = td->td_proc;
 	frame = td->td_frame;
-	sa = &td->td_sa;
 
 	sa->args[0] = frame->tf_rbx;
 	sa->args[1] = frame->tf_rcx;
diff --git a/sys/arm/arm/syscall.c b/sys/arm/arm/syscall.c
index 8c33fff..1ff48ab 100644
--- a/sys/arm/arm/syscall.c
+++ b/sys/arm/arm/syscall.c
@@ -99,14 +99,12 @@ __FBSDID("$FreeBSD$");
 void swi_handler(struct trapframe *);
 
 int
-cpu_fetch_syscall_args(struct thread *td)
+cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
 	register_t *ap;
-	struct syscall_args *sa;
 	int error;
 
-	sa = &td->td_sa;
 	sa->code = td->td_frame->tf_r7;
 	ap = &td->td_frame->tf_r0;
 	if (sa->code == SYS_syscall) {
@@ -143,14 +141,15 @@ cpu_fetch_syscall_args(struct thread *td)
 static void
 syscall(struct thread *td, struct trapframe *frame)
 {
+	struct syscall_args sa;
 	int error;
 
-	td->td_sa.nap = 4;
+	sa.nap = 4;
 
-	error = syscallenter(td);
+	error = syscallenter(td, &sa);
 	KASSERT(error != 0 || td->td_ar == NULL,
 	    ("returning from syscall with td_ar set!"));
-	syscallret(td, error);
+	syscallret(td, error, &sa);
 }
 
 void
diff --git a/sys/arm/cloudabi32/cloudabi32_sysvec.c b/sys/arm/cloudabi32/cloudabi32_sysvec.c
index a0bebcc..100fa47 100644
--- a/sys/arm/cloudabi32/cloudabi32_sysvec.c
+++ b/sys/arm/cloudabi32/cloudabi32_sysvec.c
@@ -67,15 +67,11 @@ cloudabi32_proc_setregs(struct thread *td, struct image_params *imgp,
 }
 
 static int
-cloudabi32_fetch_syscall_args(struct thread *td)
+cloudabi32_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
-	struct trapframe *frame;
-	struct syscall_args *sa;
+	struct trapframe *frame = td->td_frame;
 	int error;
 
-	frame = td->td_frame;
-	sa = &td->td_sa;
-
 	/* Obtain system call number. */
 	sa->code = frame->tf_r12;
 	if (sa->code >= CLOUDABI32_SYS_MAXSYSCALL)
diff --git a/sys/arm64/arm64/trap.c b/sys/arm64/arm64/trap.c
index bb9fe75..d7209de1 100644
--- a/sys/arm64/arm64/trap.c
+++ b/sys/arm64/arm64/trap.c
@@ -92,17 +92,15 @@ call_trapsignal(struct thread *td, int sig, int code, void *addr)
 }
 
 int
-cpu_fetch_syscall_args(struct thread *td)
+cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
 	register_t *ap;
-	struct syscall_args *sa;
 	int nap;
 
 	nap = 8;
 	p = td->td_proc;
 	ap = td->td_frame->tf_x;
-	sa = &td->td_sa;
 
 	sa->code = td->td_frame->tf_x[8];
 
@@ -134,11 +132,12 @@ cpu_fetch_syscall_args(struct thread *td)
 static void
 svc_handler(struct thread *td, struct trapframe *frame)
 {
+	struct syscall_args sa;
 	int error;
 
 	if ((frame->tf_esr & ESR_ELx_ISS_MASK) == 0) {
-		error = syscallenter(td);
-		syscallret(td, error);
+		error = syscallenter(td, &sa);
+		syscallret(td, error, &sa);
 	} else {
 		call_trapsignal(td, SIGILL, ILL_ILLOPN, (void *)frame->tf_elr);
 		userret(td, frame);
diff --git a/sys/arm64/cloudabi64/cloudabi64_sysvec.c b/sys/arm64/cloudabi64/cloudabi64_sysvec.c
index f6e75f5..fbad0ba 100644
--- a/sys/arm64/cloudabi64/cloudabi64_sysvec.c
+++ b/sys/arm64/cloudabi64/cloudabi64_sysvec.c
@@ -67,15 +67,11 @@ cloudabi64_proc_setregs(struct thread *td, struct image_params *imgp,
 }
 
 static int
-cloudabi64_fetch_syscall_args(struct thread *td)
+cloudabi64_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
-	struct trapframe *frame;
-	struct syscall_args *sa;
+	struct trapframe *frame = td->td_frame;
 	int i;
 
-	frame = td->td_frame;
-	sa = &td->td_sa;
-
 	/* Obtain system call number. */
 	sa->code = frame->tf_x[8];
 	if (sa->code >= CLOUDABI64_SYS_MAXSYSCALL)
diff --git a/sys/compat/ia32/ia32_util.h b/sys/compat/ia32/ia32_util.h
index 41aad4e..6b5f9a1 100644
--- a/sys/compat/ia32/ia32_util.h
+++ b/sys/compat/ia32/ia32_util.h
@@ -50,7 +50,7 @@
 #define	IA32_MAXVMEM	0			/* Unlimited */
 
 struct syscall_args;
-int ia32_fetch_syscall_args(struct thread *td);
+int ia32_fetch_syscall_args(struct thread *td, struct syscall_args *sa);
 void ia32_set_syscall_retval(struct thread *, int);
 void ia32_fixlimit(struct rlimit *rl, int which);
 
diff --git a/sys/compat/linux/linux_fork.c b/sys/compat/linux/linux_fork.c
index 930be5d..971006d 100644
--- a/sys/compat/linux/linux_fork.c
+++ b/sys/compat/linux/linux_fork.c
@@ -306,7 +306,6 @@ linux_clone_thread(struct thread *td, struct linux_clone_args *args)
 	    __rangeof(struct thread, td_startzero, td_endzero));
 	bcopy(&td->td_startcopy, &newtd->td_startcopy,
 	    __rangeof(struct thread, td_startcopy, td_endcopy));
-	newtd->td_sa = td->td_sa;
 
 	newtd->td_proc = p;
 	thread_cow_get(newtd, td);
diff --git a/sys/i386/cloudabi32/cloudabi32_sysvec.c b/sys/i386/cloudabi32/cloudabi32_sysvec.c
index e50a19c..c2a21fa 100644
--- a/sys/i386/cloudabi32/cloudabi32_sysvec.c
+++ b/sys/i386/cloudabi32/cloudabi32_sysvec.c
@@ -85,15 +85,11 @@ cloudabi32_proc_setregs(struct thread *td, struct image_params *imgp,
 }
 
 static int
-cloudabi32_fetch_syscall_args(struct thread *td)
+cloudabi32_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
-	struct trapframe *frame;
-	struct syscall_args *sa;
+	struct trapframe *frame = td->td_frame;
 	int error;
 
-	frame = td->td_frame;
-	sa = &td->td_sa;
-
 	/* Obtain system call number. */
 	sa->code = frame->tf_eax;
 	if (sa->code >= CLOUDABI32_SYS_MAXSYSCALL)
diff --git a/sys/i386/i386/trap.c b/sys/i386/i386/trap.c
index 3c8f4b5..7c16b24 100644
--- a/sys/i386/i386/trap.c
+++ b/sys/i386/i386/trap.c
@@ -1012,18 +1012,16 @@ dblfault_handler()
 }
 
 int
-cpu_fetch_syscall_args(struct thread *td)
+cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
 	struct trapframe *frame;
-	struct syscall_args *sa;
 	caddr_t params;
 	long tmp;
 	int error;
 
 	p = td->td_proc;
 	frame = td->td_frame;
-	sa = &td->td_sa;
 
 	params = (caddr_t)frame->tf_esp + sizeof(int);
 	sa->code = frame->tf_eax;
@@ -1084,6 +1082,7 @@ void
 syscall(struct trapframe *frame)
 {
 	struct thread *td;
+	struct syscall_args sa;
 	register_t orig_tf_eflags;
 	int error;
 	ksiginfo_t ksi;
@@ -1100,7 +1099,7 @@ syscall(struct trapframe *frame)
 	td = curthread;
 	td->td_frame = frame;
 
-	error = syscallenter(td);
+	error = syscallenter(td, &sa);
 
 	/*
 	 * Traced syscall.
@@ -1116,10 +1115,10 @@ syscall(struct trapframe *frame)
 
 	KASSERT(PCB_USER_FPU(td->td_pcb),
 	    ("System call %s returning with kernel FPU ctx leaked",
-	     syscallname(td->td_proc, td->td_sa.code)));
+	     syscallname(td->td_proc, sa.code)));
 	KASSERT(td->td_pcb->pcb_save == get_pcb_user_save_td(td),
 	    ("System call %s returning with mangled pcb_save",
-	     syscallname(td->td_proc, td->td_sa.code)));
+	     syscallname(td->td_proc, sa.code)));
 
-	syscallret(td, error);
+	syscallret(td, error, &sa);
 }
diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index a4919a0..49fafdc 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -850,15 +850,13 @@ linux_rt_sigreturn(struct thread *td, struct linux_rt_sigreturn_args *args)
 }
 
 static int
-linux_fetch_syscall_args(struct thread *td)
+linux_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
 	struct trapframe *frame;
-	struct syscall_args *sa;
 
 	p = td->td_proc;
 	frame = td->td_frame;
-	sa = &td->td_sa;
 
 	sa->code = frame->tf_eax;
 	sa->args[0] = frame->tf_ebx;
diff --git a/sys/kern/init_main.c b/sys/kern/init_main.c
index 2599ff4..a1d9846 100644
--- a/sys/kern/init_main.c
+++ b/sys/kern/init_main.c
@@ -369,7 +369,8 @@ SYSINIT(diagwarn2, SI_SUB_LAST, SI_ORDER_THIRD + 2,
 #endif
 
 static int
-null_fetch_syscall_args(struct thread *td __unused)
+null_fetch_syscall_args(struct thread *td __unused,
+    struct syscall_args *sa __unused)
 {
 
 	panic("null_fetch_syscall_args");
diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
index b63bc65..c7680aa 100644
--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -478,7 +478,6 @@ do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *
 
 	bcopy(&td->td_startcopy, &td2->td_startcopy,
 	    __rangeof(struct thread, td_startcopy, td_endcopy));
-	td2->td_sa = td->td_sa;
 
 	bcopy(&p2->p_comm, &td2->td_name, sizeof(td2->td_name));
 	td2->td_sigstk = td->td_sigstk;
@@ -1104,7 +1103,7 @@ fork_return(struct thread *td, struct trapframe *frame)
 		 */
 		PROC_LOCK(p);
 		td->td_dbgflags |= TDB_SCX;
-		_STOPEVENT(p, S_SCX, td->td_sa.code);
+		_STOPEVENT(p, S_SCX, td->td_dbg_sc_code);
 		if ((p->p_ptevents & PTRACE_SCX) != 0 ||
 		    (td->td_dbgflags & TDB_BORN) != 0)
 			ptracestop(td, SIGTRAP, NULL);
diff --git a/sys/kern/kern_kthread.c b/sys/kern/kern_kthread.c
index 69c1140..520bf97 100644
--- a/sys/kern/kern_kthread.c
+++ b/sys/kern/kern_kthread.c
@@ -276,7 +276,6 @@ kthread_add(void (*func)(void *), void *arg, struct proc *p,
 	newtd->td_sleeptimo = 0;
 	bcopy(&oldtd->td_startcopy, &newtd->td_startcopy,
 	    __rangeof(struct thread, td_startcopy, td_endcopy));
-	newtd->td_sa = oldtd->td_sa;
 
 	/* set up arg0 for 'ps', et al */
 	va_start(ap, fmt);
diff --git a/sys/kern/kern_thr.c b/sys/kern/kern_thr.c
index 6bebac9..c39986d 100644
--- a/sys/kern/kern_thr.c
+++ b/sys/kern/kern_thr.c
@@ -235,7 +235,6 @@ thread_create(struct thread *td, struct rtprio *rtp,
 	newtd->td_sleeptimo = 0;
 	bcopy(&td->td_startcopy, &newtd->td_startcopy,
 	    __rangeof(struct thread, td_startcopy, td_endcopy));
-	newtd->td_sa = td->td_sa;
 	newtd->td_proc = td->td_proc;
 	newtd->td_rb_list = newtd->td_rbp_list = newtd->td_rb_inact = 0;
 	thread_cow_get(newtd, td);
diff --git a/sys/kern/subr_syscall.c b/sys/kern/subr_syscall.c
index 0182884..2bcad34 100644
--- a/sys/kern/subr_syscall.c
+++ b/sys/kern/subr_syscall.c
@@ -52,15 +52,13 @@ __FBSDID("$FreeBSD$");
 #include <security/audit/audit.h>
 
 static inline int
-syscallenter(struct thread *td)
+syscallenter(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
-	struct syscall_args *sa;
 	int error, traced;
 
 	PCPU_INC(cnt.v_syscall);
 	p = td->td_proc;
-	sa = &td->td_sa;
 
 	td->td_pticks = 0;
 	if (td->td_cowgen != p->p_cowgen)
@@ -73,7 +71,7 @@ syscallenter(struct thread *td)
 			td->td_dbgflags |= TDB_SCE;
 		PROC_UNLOCK(p);
 	}
-	error = (p->p_sysent->sv_fetch_syscall_args)(td);
+	error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
 #ifdef KTRACE
 	if (KTRPOINT(td, KTR_SYSCALL))
 		ktrsyscall(sa->code, sa->narg, sa->args);
@@ -87,6 +85,8 @@ syscallenter(struct thread *td)
 		STOPEVENT(p, S_SCE, sa->narg);
 		if (p->p_flag & P_TRACED) {
 			PROC_LOCK(p);
+			td->td_dbg_sc_code = sa->code;
+			td->td_dbg_sc_narg = sa->narg;
 			if (p->p_ptevents & PTRACE_SCE)
 				ptracestop((td), SIGTRAP, NULL);
 			PROC_UNLOCK(p);
@@ -96,7 +96,11 @@ syscallenter(struct thread *td)
 			 * Reread syscall number and arguments if
 			 * debugger modified registers or memory.
 			 */
-			error = (p->p_sysent->sv_fetch_syscall_args)(td);
+			error = (p->p_sysent->sv_fetch_syscall_args)(td, sa);
+			PROC_LOCK(p);
+			td->td_dbg_sc_code = sa->code;
+			td->td_dbg_sc_narg = sa->narg;
+			PROC_UNLOCK(p);
 #ifdef KTRACE
 			if (KTRPOINT(td, KTR_SYSCALL))
 				ktrsyscall(sa->code, sa->narg, sa->args);
@@ -158,10 +162,9 @@ syscallenter(struct thread *td)
 }
 
 static inline void
-syscallret(struct thread *td, int error)
+syscallret(struct thread *td, int error, struct syscall_args *sa)
 {
 	struct proc *p, *p2;
-	struct syscall_args *sa;
 	ksiginfo_t ksi;
 	int traced, error1;
 
@@ -169,7 +172,6 @@ syscallret(struct thread *td, int error)
 	    ("fork() did not clear TDP_FORKING upon completion"));
 
 	p = td->td_proc;
-	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 :
diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c
index e0c4806..a8513c9 100644
--- a/sys/kern/sys_process.c
+++ b/sys/kern/sys_process.c
@@ -1347,8 +1347,8 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
 		pl->pl_siglist = td2->td_siglist;
 		strcpy(pl->pl_tdname, td2->td_name);
 		if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) != 0) {
-			pl->pl_syscall_code = td2->td_sa.code;
-			pl->pl_syscall_narg = td2->td_sa.narg;
+			pl->pl_syscall_code = td2->td_dbg_sc_code;
+			pl->pl_syscall_narg = td2->td_dbg_sc_narg;
 		} else {
 			pl->pl_syscall_code = 0;
 			pl->pl_syscall_narg = 0;
diff --git a/sys/mips/mips/trap.c b/sys/mips/mips/trap.c
index 396f69b..f98fc97 100644
--- a/sys/mips/mips/trap.c
+++ b/sys/mips/mips/trap.c
@@ -339,16 +339,12 @@ static int emulate_unaligned_access(struct trapframe *frame, int mode);
 extern void fswintrberr(void); /* XXX */
 
 int
-cpu_fetch_syscall_args(struct thread *td)
+cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
-	struct trapframe *locr0;
+	struct trapframe *locr0 = td->td_frame;
 	struct sysentvec *se;
-	struct syscall_args *sa;
 	int error, nsaved;
 
-	locr0 = td->td_frame;
-	sa = &td->td_sa;
-	
 	bzero(sa->args, sizeof(sa->args));
 
 	/* compute next PC after syscall instruction */
@@ -790,18 +786,19 @@ dofault:
 
 	case T_SYSCALL + T_USER:
 		{
+			struct syscall_args sa;
 			int error;
 
-			td->td_sa.trapframe = trapframe;
-			error = syscallenter(td);
+			sa.trapframe = trapframe;
+			error = syscallenter(td, &sa);
 
 #if !defined(SMP) && (defined(DDB) || defined(DEBUG))
 			if (trp == trapdebug)
-				trapdebug[TRAPSIZE - 1].code = td->td_sa.code;
+				trapdebug[TRAPSIZE - 1].code = sa.code;
 			else
-				trp[-1].code = td->td_sa.code;
+				trp[-1].code = sa.code;
 #endif
-			trapdebug_enter(td->td_frame, -td->td_sa.code);
+			trapdebug_enter(td->td_frame, -sa.code);
 
 			/*
 			 * The sync'ing of I & D caches for SYS_ptrace() is
@@ -809,7 +806,7 @@ dofault:
 			 * instead of being done here under a special check
 			 * for SYS_ptrace().
 			 */
-			syscallret(td, error);
+			syscallret(td, error, &sa);
 			return (trapframe->pc);
 		}
 
diff --git a/sys/powerpc/powerpc/trap.c b/sys/powerpc/powerpc/trap.c
index 95fb554..4464dd8 100644
--- a/sys/powerpc/powerpc/trap.c
+++ b/sys/powerpc/powerpc/trap.c
@@ -484,18 +484,16 @@ handle_onfault(struct trapframe *frame)
 }
 
 int
-cpu_fetch_syscall_args(struct thread *td)
+cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
 	struct trapframe *frame;
-	struct syscall_args *sa;
 	caddr_t	params;
 	size_t argsz;
 	int error, n, i;
 
 	p = td->td_proc;
 	frame = td->td_frame;
-	sa = &td->td_sa;
 
 	sa->code = frame->fixreg[0];
 	params = (caddr_t)(frame->fixreg + FIRSTARG);
@@ -577,6 +575,7 @@ void
 syscall(struct trapframe *frame)
 {
 	struct thread *td;
+	struct syscall_args sa;
 	int error;
 
 	td = curthread;
@@ -591,8 +590,8 @@ syscall(struct trapframe *frame)
             "r"(td->td_pcb->pcb_cpu.aim.usr_vsid), "r"(USER_SLB_SLBE));
 #endif
 
-	error = syscallenter(td);
-	syscallret(td, error);
+	error = syscallenter(td, &sa);
+	syscallret(td, error, &sa);
 }
 
 #ifdef __powerpc64__
diff --git a/sys/riscv/riscv/trap.c b/sys/riscv/riscv/trap.c
index 7e85c16..22d27f4 100644
--- a/sys/riscv/riscv/trap.c
+++ b/sys/riscv/riscv/trap.c
@@ -89,16 +89,14 @@ call_trapsignal(struct thread *td, int sig, int code, void *addr)
 }
 
 int
-cpu_fetch_syscall_args(struct thread *td)
+cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct proc *p;
 	register_t *ap;
-	struct syscall_args *sa;
 	int nap;
 
 	nap = 8;
 	p = td->td_proc;
-	sa = &td->td_sa;
 	ap = &td->td_frame->tf_a[0];
 
 	sa->code = td->td_frame->tf_t[0];
@@ -153,14 +151,15 @@ dump_regs(struct trapframe *frame)
 static void
 svc_handler(struct trapframe *frame)
 {
+	struct syscall_args sa;
 	struct thread *td;
 	int error;
 
 	td = curthread;
 	td->td_frame = frame;
 
-	error = syscallenter(td);
-	syscallret(td, error);
+	error = syscallenter(td, &sa);
+	syscallret(td, error, &sa);
 }
 
 static void
diff --git a/sys/sparc64/sparc64/trap.c b/sys/sparc64/sparc64/trap.c
index e77ccf7..73719f2 100644
--- a/sys/sparc64/sparc64/trap.c
+++ b/sys/sparc64/sparc64/trap.c
@@ -538,19 +538,17 @@ trap_pfault(struct thread *td, struct trapframe *tf)
 #define	REG_MAXARGS	6
 
 int
-cpu_fetch_syscall_args(struct thread *td)
+cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa)
 {
 	struct trapframe *tf;
 	struct proc *p;
 	register_t *argp;
-	struct syscall_args *sa;
 	int reg;
 	int regcnt;
 	int error;
 
 	p = td->td_proc;
 	tf = td->td_frame;
-	sa = &td->td_sa;
 	reg = 0;
 	regcnt = REG_MAXARGS;
 
@@ -598,6 +596,7 @@ void
 syscall(struct trapframe *tf)
 {
 	struct thread *td;
+	struct syscall_args sa;
 	int error;
 
 	td = curthread;
@@ -613,6 +612,6 @@ syscall(struct trapframe *tf)
 	td->td_pcb->pcb_tpc = tf->tf_tpc;
 	TF_DONE(tf);
 
-	error = syscallenter(td);
-	syscallret(td, error);
+	error = syscallenter(td, &sa);
+	syscallret(td, error, &sa);
 }
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 11947db6..d32807a 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -142,7 +142,6 @@ struct pargs {
  *      j - locked by proc slock
  *      k - only accessed by curthread
  *	k*- only accessed by curthread and from an interrupt
- *	kx- only accessed by curthread and by debugger
  *      l - the attaching proc or attaching proc parent
  *      m - Giant
  *      n - not locked, lazy
@@ -296,8 +295,8 @@ struct thread {
 	u_char		td_pri_class;	/* (t) Scheduling class. */
 	u_char		td_user_pri;	/* (t) User pri from estcpu and nice. */
 	u_char		td_base_user_pri; /* (t) Base user pri */
-	u_int		td_padding3;
-	u_int		td_padding4;
+	u_int		td_dbg_sc_code;	/* (c) Syscall code to debugger. */
+	u_int		td_dbg_sc_narg;	/* (c) Syscall arg count to debugger.*/
 	uintptr_t	td_rb_list;	/* (k) Robust list head. */
 	uintptr_t	td_rbp_list;	/* (k) Robust priv list head. */
 	uintptr_t	td_rb_inact;	/* (k) Current in-action mutex loc. */
@@ -344,8 +343,6 @@ struct thread {
 	sbintime_t	td_sleeptimo;	/* (t) Sleep timeout. */
 	sigqueue_t	td_sigqueue;	/* (c) Sigs arrived, not delivered. */
 #define	td_siglist	td_sigqueue.sq_signals
-	struct syscall_args td_sa;	/* (kx) Syscall parameters. Copied on
-					   fork for child tracing. */
 };
 
 struct thread0_storage {
@@ -1054,7 +1051,7 @@ void	userret(struct thread *, struct trapframe *);
 void	cpu_exit(struct thread *);
 void	exit1(struct thread *, int, int) __dead2;
 void	cpu_copy_thread(struct thread *td, struct thread *td0);
-int	cpu_fetch_syscall_args(struct thread *td);
+int	cpu_fetch_syscall_args(struct thread *td, struct syscall_args *sa);
 void	cpu_fork(struct thread *, struct proc *, struct thread *, int);
 void	cpu_fork_kthread_handler(struct thread *, void (*)(void *), void *);
 void	cpu_set_syscall_retval(struct thread *, int);
diff --git a/sys/sys/sysent.h b/sys/sys/sysent.h
index f1f4590..8313fc0 100644
--- a/sys/sys/sysent.h
+++ b/sys/sys/sysent.h
@@ -119,7 +119,8 @@ struct sysentvec {
 	u_long		*sv_maxssiz;
 	u_int		sv_flags;
 	void		(*sv_set_syscall_retval)(struct thread *, int);
-	int		(*sv_fetch_syscall_args)(struct thread *);
+	int		(*sv_fetch_syscall_args)(struct thread *, struct
+			    syscall_args *);
 	const char	**sv_syscallnames;
 	vm_offset_t	sv_timekeep_base;
 	vm_offset_t	sv_shared_page_base;