aboutsummaryrefslogtreecommitdiff
path: root/arch
diff options
context:
space:
mode:
authorDavid S. Miller <davem@davemloft.net>2008-05-11 19:35:21 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2008-05-15 07:50:06 -0700
commitb6c84db1836c4af6c84d2e6d69c060354ff0d9e0 (patch)
tree620d58f58e2d12822c347b4fa366a4ce3cf88799 /arch
parent385a8d8adfdd806bda12128c3744b564ec112293 (diff)
sparc: Fix debugger syscall restart interactions.
[ This is a 2.6.25 backport of upstream changeset 28e6103665301ce60634e8a77f0b657c6cc099de with sparc32 build fixes from Robert Reif ] So, forever, we've had this ptrace_signal_deliver implementation which tries to handle all of the nasties that can occur when the debugger looks at a process about to take a signal. It's meant to address all of these issues inside of the kernel so that the debugger need not be mindful of such things. Problem is, this doesn't work. The idea was that we should do the syscall restart business first, so that the debugger captures that state. Otherwise, if the debugger for example saves the child's state, makes the child execute something else, then restores the saved state, we won't handle the syscall restart properly because we lose the "we're in a syscall" state. The code here worked for most cases, but if the debugger actually passes the signal through to the child unaltered, it's possible that we would do a syscall restart when we shouldn't have. In particular this breaks the case of debugging a process under a gdb which is being debugged by yet another gdb. gdb uses sigsuspend to wait for SIGCHLD of the inferior, but if gdb itself is being debugged by a top-level gdb we get a ptrace_stop(). The top-level gdb does a PTRACE_CONT with SIGCHLD to let the inferior gdb see the signal. But ptrace_signal_deliver() assumed the debugger would cancel out the signal and therefore did a syscall restart, because the return error was ERESTARTNOHAND. Fix this by simply making ptrace_signal_deliver() a nop, and providing a way for the debugger to control system call restarting properly: 1) Report a "in syscall" software bit in regs->{tstate,psr}. It is set early on in trap entry to a system call and is fully visible to the debugger via ptrace() and regsets. 2) Test this bit right before doing a syscall restart. We have to do a final recheck right after get_signal_to_deliver() in case the debugger cleared the bit during ptrace_stop(). 3) Clear the bit in trap return so we don't accidently try to set that bit in the real register. As a result we also get a ptrace_{is,clear}_syscall() for sparc32 just like sparc64 has. M68K has this same exact bug, and is now the only other user of the ptrace_signal_deliver hook. It needs to be fixed in the same exact way as sparc. Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch')
-rw-r--r--arch/sparc/kernel/entry.S2
-rw-r--r--arch/sparc/kernel/ptrace.c4
-rw-r--r--arch/sparc/kernel/rtrap.S11
-rw-r--r--arch/sparc/kernel/signal.c64
-rw-r--r--arch/sparc64/kernel/etrap.S7
-rw-r--r--arch/sparc64/kernel/ptrace.c12
-rw-r--r--arch/sparc64/kernel/rtrap.S1
-rw-r--r--arch/sparc64/kernel/signal.c67
-rw-r--r--arch/sparc64/kernel/signal32.c30
9 files changed, 101 insertions, 97 deletions
diff --git a/arch/sparc/kernel/entry.S b/arch/sparc/kernel/entry.S
index c2eed8f7151..1ea92e7391c 100644
--- a/arch/sparc/kernel/entry.S
+++ b/arch/sparc/kernel/entry.S
@@ -1398,6 +1398,8 @@ ret_from_fork:
.align 4
.globl linux_sparc_syscall
linux_sparc_syscall:
+ sethi %hi(PSR_SYSCALL), %l4
+ or %l0, %l4, %l0
/* Direct access to user regs, must faster. */
cmp %g1, NR_SYSCALLS
bgeu linux_sparc_ni_syscall
diff --git a/arch/sparc/kernel/ptrace.c b/arch/sparc/kernel/ptrace.c
index 60dfc65549d..81f3b929743 100644
--- a/arch/sparc/kernel/ptrace.c
+++ b/arch/sparc/kernel/ptrace.c
@@ -170,8 +170,8 @@ static int genregs32_set(struct task_struct *target,
switch (pos) {
case 32: /* PSR */
psr = regs->psr;
- psr &= ~PSR_ICC;
- psr |= (reg & PSR_ICC);
+ psr &= ~(PSR_ICC | PSR_SYSCALL);
+ psr |= (reg & (PSR_ICC | PSR_SYSCALL));
regs->psr = psr;
break;
case 33: /* PC */
diff --git a/arch/sparc/kernel/rtrap.S b/arch/sparc/kernel/rtrap.S
index 77ca6fd8125..ab818cdc4cc 100644
--- a/arch/sparc/kernel/rtrap.S
+++ b/arch/sparc/kernel/rtrap.S
@@ -50,8 +50,9 @@ rtrap_7win_patch5: and %g1, 0x7f, %g1
ret_trap_entry:
ret_trap_lockless_ipi:
andcc %t_psr, PSR_PS, %g0
+ sethi %hi(PSR_SYSCALL), %g1
be 1f
- nop
+ andn %t_psr, %g1, %t_psr
wr %t_psr, 0x0, %psr
b ret_trap_kernel
@@ -73,7 +74,6 @@ signal_p:
ld [%sp + STACKFRAME_SZ + PT_PSR], %t_psr
mov %l5, %o1
- mov %l6, %o2
call do_signal
add %sp, STACKFRAME_SZ, %o0 ! pt_regs ptr
@@ -81,6 +81,8 @@ signal_p:
ld [%sp + STACKFRAME_SZ + PT_PSR], %t_psr
clr %l6
ret_trap_continue:
+ sethi %hi(PSR_SYSCALL), %g1
+ andn %t_psr, %g1, %t_psr
wr %t_psr, 0x0, %psr
WRITE_PAUSE
@@ -137,8 +139,9 @@ ret_trap_userwins_ok:
LOAD_PT_PRIV(sp, t_psr, t_pc, t_npc)
or %t_pc, %t_npc, %g2
andcc %g2, 0x3, %g0
+ sethi %hi(PSR_SYSCALL), %g2
be 1f
- nop
+ andn %t_psr, %g2, %t_psr
b ret_trap_unaligned_pc
add %sp, STACKFRAME_SZ, %o0
@@ -201,6 +204,8 @@ rtrap_patch5: and %g1, 0xff, %g1
1:
LOAD_PT_ALL(sp, t_psr, t_pc, t_npc, g1)
2:
+ sethi %hi(PSR_SYSCALL), %twin_tmp1
+ andn %t_psr, %twin_tmp1, %t_psr
wr %t_psr, 0x0, %psr
WRITE_PAUSE
diff --git a/arch/sparc/kernel/signal.c b/arch/sparc/kernel/signal.c
index c80a232db6d..e85023bb8e5 100644
--- a/arch/sparc/kernel/signal.c
+++ b/arch/sparc/kernel/signal.c
@@ -178,6 +178,9 @@ static inline void do_new_sigreturn (struct pt_regs *regs)
regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
| (regs->psr & (PSR_ICC | PSR_EF));
+ /* Prevent syscall restart. */
+ pt_regs_clear_syscall(regs);
+
err |= __get_user(fpu_save, &sf->fpu_save);
if (fpu_save)
@@ -299,6 +302,9 @@ asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);
+ /* Prevent syscall restart. */
+ pt_regs_clear_syscall(regs);
+
err |= __get_user(fpu_save, &sf->fpu_save);
if (fpu_save)
@@ -1008,13 +1014,13 @@ static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
* want to handle. Thus you cannot kill init even with a SIGKILL even by
* mistake.
*/
-asmlinkage void do_signal(struct pt_regs * regs, unsigned long orig_i0, int restart_syscall)
+asmlinkage void do_signal(struct pt_regs * regs, unsigned long orig_i0)
{
- siginfo_t info;
- struct sparc_deliver_cookie cookie;
struct k_sigaction ka;
- int signr;
+ int restart_syscall;
sigset_t *oldset;
+ siginfo_t info;
+ int signr;
/*
* XXX Disable svr4 signal handling until solaris emulation works.
@@ -1027,18 +1033,28 @@ asmlinkage void do_signal(struct pt_regs * regs, unsigned long orig_i0, int rest
int svr4_signal = current->personality == PER_SVR4;
#endif
- cookie.restart_syscall = restart_syscall;
- cookie.orig_i0 = orig_i0;
+ if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
+ restart_syscall = 1;
+ else
+ restart_syscall = 0;
if (test_thread_flag(TIF_RESTORE_SIGMASK))
oldset = &current->saved_sigmask;
else
oldset = &current->blocked;
- signr = get_signal_to_deliver(&info, &ka, regs, &cookie);
+ signr = get_signal_to_deliver(&info, &ka, regs, NULL);
+
+ /* If the debugger messes with the program counter, it clears
+ * the software "in syscall" bit, directing us to not perform
+ * a syscall restart.
+ */
+ if (restart_syscall && !pt_regs_is_syscall(regs))
+ restart_syscall = 0;
+
if (signr > 0) {
- if (cookie.restart_syscall)
- syscall_restart(cookie.orig_i0, regs, &ka.sa);
+ if (restart_syscall)
+ syscall_restart(orig_i0, regs, &ka.sa);
handle_signal(signr, &ka, &info, oldset,
regs, svr4_signal);
/* a signal was successfully delivered; the saved
@@ -1050,16 +1066,16 @@ asmlinkage void do_signal(struct pt_regs * regs, unsigned long orig_i0, int rest
clear_thread_flag(TIF_RESTORE_SIGMASK);
return;
}
- if (cookie.restart_syscall &&
+ if (restart_syscall &&
(regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
regs->u_regs[UREG_I0] == ERESTARTSYS ||
regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
/* replay the system call when we are done */
- regs->u_regs[UREG_I0] = cookie.orig_i0;
+ regs->u_regs[UREG_I0] = orig_i0;
regs->pc -= 4;
regs->npc -= 4;
}
- if (cookie.restart_syscall &&
+ if (restart_syscall &&
regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
regs->u_regs[UREG_G1] = __NR_restart_syscall;
regs->pc -= 4;
@@ -1111,27 +1127,3 @@ do_sys_sigstack(struct sigstack __user *ssptr, struct sigstack __user *ossptr,
out:
return ret;
}
-
-void ptrace_signal_deliver(struct pt_regs *regs, void *cookie)
-{
- struct sparc_deliver_cookie *cp = cookie;
-
- if (cp->restart_syscall &&
- (regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
- regs->u_regs[UREG_I0] == ERESTARTSYS ||
- regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
- /* replay the system call when we are done */
- regs->u_regs[UREG_I0] = cp->orig_i0;
- regs->pc -= 4;
- regs->npc -= 4;
- cp->restart_syscall = 0;
- }
-
- if (cp->restart_syscall &&
- regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
- regs->u_regs[UREG_G1] = __NR_restart_syscall;
- regs->pc -= 4;
- regs->npc -= 4;
- cp->restart_syscall = 0;
- }
-}
diff --git a/arch/sparc64/kernel/etrap.S b/arch/sparc64/kernel/etrap.S
index 4b2bf9eb447..b087e977bc5 100644
--- a/arch/sparc64/kernel/etrap.S
+++ b/arch/sparc64/kernel/etrap.S
@@ -27,11 +27,12 @@
.text
.align 64
- .globl etrap, etrap_irq, etraptl1
+ .globl etrap_syscall, etrap, etrap_irq, etraptl1
etrap: rdpr %pil, %g2
-etrap_irq:
- TRAP_LOAD_THREAD_REG(%g6, %g1)
+etrap_irq: clr %g3
+etrap_syscall: TRAP_LOAD_THREAD_REG(%g6, %g1)
rdpr %tstate, %g1
+ or %g1, %g3, %g1
sllx %g2, 20, %g3
andcc %g1, TSTATE_PRIV, %g0
or %g1, %g3, %g1
diff --git a/arch/sparc64/kernel/ptrace.c b/arch/sparc64/kernel/ptrace.c
index b803fe9b2c8..f6c9fc92921 100644
--- a/arch/sparc64/kernel/ptrace.c
+++ b/arch/sparc64/kernel/ptrace.c
@@ -287,11 +287,11 @@ static int genregs64_set(struct task_struct *target,
32 * sizeof(u64),
33 * sizeof(u64));
if (!ret) {
- /* Only the condition codes can be modified
- * in the %tstate register.
+ /* Only the condition codes and the "in syscall"
+ * state can be modified in the %tstate register.
*/
- tstate &= (TSTATE_ICC | TSTATE_XCC);
- regs->tstate &= ~(TSTATE_ICC | TSTATE_XCC);
+ tstate &= (TSTATE_ICC | TSTATE_XCC | TSTATE_SYSCALL);
+ regs->tstate &= ~(TSTATE_ICC | TSTATE_XCC | TSTATE_SYSCALL);
regs->tstate |= tstate;
}
}
@@ -657,8 +657,10 @@ static int genregs32_set(struct task_struct *target,
switch (pos) {
case 32: /* PSR */
tstate = regs->tstate;
- tstate &= ~(TSTATE_ICC | TSTATE_XCC);
+ tstate &= ~(TSTATE_ICC | TSTATE_XCC | TSTATE_SYSCALL);
tstate |= psr_to_tstate_icc(reg);
+ if (reg & PSR_SYSCALL)
+ tstate |= TSTATE_SYSCALL;
regs->tstate = tstate;
break;
case 33: /* PC */
diff --git a/arch/sparc64/kernel/rtrap.S b/arch/sparc64/kernel/rtrap.S
index 079d18a11d2..5bfa79dcdd3 100644
--- a/arch/sparc64/kernel/rtrap.S
+++ b/arch/sparc64/kernel/rtrap.S
@@ -270,6 +270,7 @@ rt_continue: ldx [%sp + PTREGS_OFF + PT_V9_G1], %g1
wr %o3, %g0, %y
wrpr %l4, 0x0, %pil
wrpr %g0, 0x1, %tl
+ andn %l1, TSTATE_SYSCALL, %l1
wrpr %l1, %g0, %tstate
wrpr %l2, %g0, %tpc
wrpr %o2, %g0, %tnpc
diff --git a/arch/sparc64/kernel/signal.c b/arch/sparc64/kernel/signal.c
index 01b6f1821e3..ec016cb7197 100644
--- a/arch/sparc64/kernel/signal.c
+++ b/arch/sparc64/kernel/signal.c
@@ -336,6 +336,9 @@ void do_rt_sigreturn(struct pt_regs *regs)
regs->tpc = tpc;
regs->tnpc = tnpc;
+ /* Prevent syscall restart. */
+ pt_regs_clear_syscall(regs);
+
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
@@ -500,7 +503,7 @@ static inline void handle_signal(unsigned long signr, struct k_sigaction *ka,
}
static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
- struct sigaction *sa)
+ struct sigaction *sa)
{
switch (regs->u_regs[UREG_I0]) {
case ERESTART_RESTARTBLOCK:
@@ -524,16 +527,19 @@ static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
* want to handle. Thus you cannot kill init even with a SIGKILL even by
* mistake.
*/
-static void do_signal(struct pt_regs *regs, unsigned long orig_i0, int restart_syscall)
+static void do_signal(struct pt_regs *regs, unsigned long orig_i0, int __ignored)
{
- siginfo_t info;
- struct signal_deliver_cookie cookie;
struct k_sigaction ka;
- int signr;
+ int restart_syscall;
sigset_t *oldset;
+ siginfo_t info;
+ int signr;
- cookie.restart_syscall = restart_syscall;
- cookie.orig_i0 = orig_i0;
+ if (pt_regs_is_syscall(regs) &&
+ (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY))) {
+ restart_syscall = 1;
+ } else
+ restart_syscall = 0;
if (test_thread_flag(TIF_RESTORE_SIGMASK))
oldset = &current->saved_sigmask;
@@ -543,16 +549,24 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0, int restart_s
#ifdef CONFIG_SPARC32_COMPAT
if (test_thread_flag(TIF_32BIT)) {
extern void do_signal32(sigset_t *, struct pt_regs *,
- unsigned long, int);
- do_signal32(oldset, regs, orig_i0,
- cookie.restart_syscall);
+ int restart_syscall,
+ unsigned long orig_i0);
+ do_signal32(oldset, regs, restart_syscall, orig_i0);
return;
}
#endif
- signr = get_signal_to_deliver(&info, &ka, regs, &cookie);
+ signr = get_signal_to_deliver(&info, &ka, regs, NULL);
+
+ /* If the debugger messes with the program counter, it clears
+ * the software "in syscall" bit, directing us to not perform
+ * a syscall restart.
+ */
+ if (restart_syscall && !pt_regs_is_syscall(regs))
+ restart_syscall = 0;
+
if (signr > 0) {
- if (cookie.restart_syscall)
+ if (restart_syscall)
syscall_restart(orig_i0, regs, &ka.sa);
handle_signal(signr, &ka, &info, oldset, regs);
@@ -565,16 +579,16 @@ static void do_signal(struct pt_regs *regs, unsigned long orig_i0, int restart_s
clear_thread_flag(TIF_RESTORE_SIGMASK);
return;
}
- if (cookie.restart_syscall &&
+ if (restart_syscall &&
(regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
regs->u_regs[UREG_I0] == ERESTARTSYS ||
regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
/* replay the system call when we are done */
- regs->u_regs[UREG_I0] = cookie.orig_i0;
+ regs->u_regs[UREG_I0] = orig_i0;
regs->tpc -= 4;
regs->tnpc -= 4;
}
- if (cookie.restart_syscall &&
+ if (restart_syscall &&
regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
regs->u_regs[UREG_G1] = __NR_restart_syscall;
regs->tpc -= 4;
@@ -596,26 +610,3 @@ void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, int restart_s
if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
do_signal(regs, orig_i0, restart_syscall);
}
-
-void ptrace_signal_deliver(struct pt_regs *regs, void *cookie)
-{
- struct signal_deliver_cookie *cp = cookie;
-
- if (cp->restart_syscall &&
- (regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
- regs->u_regs[UREG_I0] == ERESTARTSYS ||
- regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
- /* replay the system call when we are done */
- regs->u_regs[UREG_I0] = cp->orig_i0;
- regs->tpc -= 4;
- regs->tnpc -= 4;
- cp->restart_syscall = 0;
- }
- if (cp->restart_syscall &&
- regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
- regs->u_regs[UREG_G1] = __NR_restart_syscall;
- regs->tpc -= 4;
- regs->tnpc -= 4;
- cp->restart_syscall = 0;
- }
-}
diff --git a/arch/sparc64/kernel/signal32.c b/arch/sparc64/kernel/signal32.c
index c55b67c614b..c1b06e2e580 100644
--- a/arch/sparc64/kernel/signal32.c
+++ b/arch/sparc64/kernel/signal32.c
@@ -295,6 +295,9 @@ void do_new_sigreturn32(struct pt_regs *regs)
regs->tstate &= ~(TSTATE_ICC|TSTATE_XCC);
regs->tstate |= psr_to_tstate_icc(psr);
+ /* Prevent syscall restart. */
+ pt_regs_clear_syscall(regs);
+
err |= __get_user(fpu_save, &sf->fpu_save);
if (fpu_save)
err |= restore_fpu_state32(regs, &sf->fpu_state);
@@ -448,6 +451,9 @@ asmlinkage void do_rt_sigreturn32(struct pt_regs *regs)
regs->tstate &= ~(TSTATE_ICC|TSTATE_XCC);
regs->tstate |= psr_to_tstate_icc(psr);
+ /* Prevent syscall restart. */
+ pt_regs_clear_syscall(regs);
+
err |= __get_user(fpu_save, &sf->fpu_save);
if (fpu_save)
err |= restore_fpu_state32(regs, &sf->fpu_state);
@@ -1280,20 +1286,24 @@ static inline void syscall_restart32(unsigned long orig_i0, struct pt_regs *regs
* mistake.
*/
void do_signal32(sigset_t *oldset, struct pt_regs * regs,
- unsigned long orig_i0, int restart_syscall)
+ int restart_syscall, unsigned long orig_i0)
{
- siginfo_t info;
- struct signal_deliver_cookie cookie;
struct k_sigaction ka;
+ siginfo_t info;
int signr;
int svr4_signal = current->personality == PER_SVR4;
- cookie.restart_syscall = restart_syscall;
- cookie.orig_i0 = orig_i0;
+ signr = get_signal_to_deliver(&info, &ka, regs, NULL);
+
+ /* If the debugger messes with the program counter, it clears
+ * the "in syscall" bit, directing us to not perform a syscall
+ * restart.
+ */
+ if (restart_syscall && !pt_regs_is_syscall(regs))
+ restart_syscall = 0;
- signr = get_signal_to_deliver(&info, &ka, regs, &cookie);
if (signr > 0) {
- if (cookie.restart_syscall)
+ if (restart_syscall)
syscall_restart32(orig_i0, regs, &ka.sa);
handle_signal32(signr, &ka, &info, oldset,
regs, svr4_signal);
@@ -1307,16 +1317,16 @@ void do_signal32(sigset_t *oldset, struct pt_regs * regs,
clear_thread_flag(TIF_RESTORE_SIGMASK);
return;
}
- if (cookie.restart_syscall &&
+ if (restart_syscall &&
(regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
regs->u_regs[UREG_I0] == ERESTARTSYS ||
regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
/* replay the system call when we are done */
- regs->u_regs[UREG_I0] = cookie.orig_i0;
+ regs->u_regs[UREG_I0] = orig_i0;
regs->tpc -= 4;
regs->tnpc -= 4;
}
- if (cookie.restart_syscall &&
+ if (restart_syscall &&
regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
regs->u_regs[UREG_G1] = __NR_restart_syscall;
regs->tpc -= 4;