sparc: Allow handling signals when stack is corrupted.

If we can't push the pending register windows onto the user's stack,
we disallow signal delivery even if the signal would be delivered on a
valid seperate signal stack.

Add a register window save area in the signal frame, and store any
unsavable windows there.

On sigreturn, if any windows are still queued up in the signal frame,
try to push them back onto the stack and if that fails we kill the
process immediately.

This allows the debug/tst-longjmp_chk2 glibc test case to pass.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 79 insertions, 93 deletions

diff --git a/arch/sparc/kernel/signal_32.c b/arch/sparc/kernel/signal_32.c
index 5e5c5fd03783..04ede8f04add 100644
--- a/arch/sparc/kernel/signal_32.c
+++ b/arch/sparc/kernel/signal_32.c
@@ -26,6 +26,8 @@
 #include <asm/pgtable.h>
 #include <asm/cacheflush.h>	/* flush_sig_insns */
 
+#include "sigutil.h"
+
 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 
 extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
@@ -39,8 +41,8 @@ struct signal_frame {
 	unsigned long		insns[2] __attribute__ ((aligned (8)));
 	unsigned int		extramask[_NSIG_WORDS - 1];
 	unsigned int		extra_size; /* Should be 0 */
-	__siginfo_fpu_t		fpu_state;
-};
+	__siginfo_rwin_t __user	*rwin_save;
+} __attribute__((aligned(8)));
 
 struct rt_signal_frame {
 	struct sparc_stackf	ss;
@@ -51,8 +53,8 @@ struct rt_signal_frame {
 	unsigned int		insns[2];
 	stack_t			stack;
 	unsigned int		extra_size; /* Should be 0 */
-	__siginfo_fpu_t		fpu_state;
-};
+	__siginfo_rwin_t __user	*rwin_save;
+} __attribute__((aligned(8)));
 
 /* Align macros */
 #define SF_ALIGNEDSZ  (((sizeof(struct signal_frame) + 7) & (~7)))
@@ -79,43 +81,13 @@ asmlinkage int sys_sigsuspend(old_sigset_t set)
 	return _sigpause_common(set);
 }
 
-static inline int
-restore_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
-{
-	int err;
-#ifdef CONFIG_SMP
-	if (test_tsk_thread_flag(current, TIF_USEDFPU))
-		regs->psr &= ~PSR_EF;
-#else
-	if (current == last_task_used_math) {
-		last_task_used_math = NULL;
-		regs->psr &= ~PSR_EF;
-	}
-#endif
-	set_used_math();
-	clear_tsk_thread_flag(current, TIF_USEDFPU);
-
-	if (!access_ok(VERIFY_READ, fpu, sizeof(*fpu)))
-		return -EFAULT;
-
-	err = __copy_from_user(&current->thread.float_regs[0], &fpu->si_float_regs[0],
-			       (sizeof(unsigned long) * 32));
-	err |= __get_user(current->thread.fsr, &fpu->si_fsr);
-	err |= __get_user(current->thread.fpqdepth, &fpu->si_fpqdepth);
-	if (current->thread.fpqdepth != 0)
-		err |= __copy_from_user(&current->thread.fpqueue[0],
-					&fpu->si_fpqueue[0],
-					((sizeof(unsigned long) +
-					(sizeof(unsigned long *)))*16));
-	return err;
-}
-
 asmlinkage void do_sigreturn(struct pt_regs *regs)
 {
 	struct signal_frame __user *sf;
 	unsigned long up_psr, pc, npc;
 	sigset_t set;
 	__siginfo_fpu_t __user *fpu_save;
+	__siginfo_rwin_t __user *rwin_save;
 	int err;
 
 	/* Always make any pending restarted system calls return -EINTR */
@@ -150,9 +122,11 @@ asmlinkage void do_sigreturn(struct pt_regs *regs)
 	pt_regs_clear_syscall(regs);
 
 	err |= __get_user(fpu_save, &sf->fpu_save);
-
 	if (fpu_save)
 		err |= restore_fpu_state(regs, fpu_save);
+	err |= __get_user(rwin_save, &sf->rwin_save);
+	if (rwin_save)
+		err |= restore_rwin_state(rwin_save);
 
 	/* This is pretty much atomic, no amount locking would prevent
 	 * the races which exist anyways.
@@ -180,6 +154,7 @@ asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
 	struct rt_signal_frame __user *sf;
 	unsigned int psr, pc, npc;
 	__siginfo_fpu_t __user *fpu_save;
+	__siginfo_rwin_t __user *rwin_save;
 	mm_segment_t old_fs;
 	sigset_t set;
 	stack_t st;
@@ -207,8 +182,7 @@ asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
 	pt_regs_clear_syscall(regs);
 
 	err |= __get_user(fpu_save, &sf->fpu_save);
-
-	if (fpu_save)
+	if (!err && fpu_save)
 		err |= restore_fpu_state(regs, fpu_save);
 	err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
 	
@@ -228,6 +202,12 @@ asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
 	do_sigaltstack((const stack_t __user *) &st, NULL, (unsigned long)sf);
 	set_fs(old_fs);
 
+	err |= __get_user(rwin_save, &sf->rwin_save);
+	if (!err && rwin_save) {
+		if (restore_rwin_state(rwin_save))
+			goto segv;
+	}
+
 	sigdelsetmask(&set, ~_BLOCKABLE);
 	spin_lock_irq(&current->sighand->siglock);
 	current->blocked = set;
@@ -280,53 +260,23 @@ static inline void __user *get_sigframe(struct sigaction *sa, struct pt_regs *re
 	return (void __user *) sp;
 }
 
-static inline int
-save_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
-{
-	int err = 0;
-#ifdef CONFIG_SMP
-	if (test_tsk_thread_flag(current, TIF_USEDFPU)) {
-		put_psr(get_psr() | PSR_EF);
-		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
-		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
-		regs->psr &= ~(PSR_EF);
-		clear_tsk_thread_flag(current, TIF_USEDFPU);
-	}
-#else
-	if (current == last_task_used_math) {
-		put_psr(get_psr() | PSR_EF);
-		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
-		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
-		last_task_used_math = NULL;
-		regs->psr &= ~(PSR_EF);
-	}
-#endif
-	err |= __copy_to_user(&fpu->si_float_regs[0],
-			      &current->thread.float_regs[0],
-			      (sizeof(unsigned long) * 32));
-	err |= __put_user(current->thread.fsr, &fpu->si_fsr);
-	err |= __put_user(current->thread.fpqdepth, &fpu->si_fpqdepth);
-	if (current->thread.fpqdepth != 0)
-		err |= __copy_to_user(&fpu->si_fpqueue[0],
-				      &current->thread.fpqueue[0],
-				      ((sizeof(unsigned long) +
-				      (sizeof(unsigned long *)))*16));
-	clear_used_math();
-	return err;
-}
-
 static int setup_frame(struct k_sigaction *ka, struct pt_regs *regs,
 		       int signo, sigset_t *oldset)
 {
 	struct signal_frame __user *sf;
-	int sigframe_size, err;
+	int sigframe_size, err, wsaved;
+	void __user *tail;
 
 	/* 1. Make sure everything is clean */
 	synchronize_user_stack();
 
-	sigframe_size = SF_ALIGNEDSZ;
-	if (!used_math())
-		sigframe_size -= sizeof(__siginfo_fpu_t);
+	wsaved = current_thread_info()->w_saved;
+
+	sigframe_size = sizeof(*sf);
+	if (used_math())
+		sigframe_size += sizeof(__siginfo_fpu_t);
+	if (wsaved)
+		sigframe_size += sizeof(__siginfo_rwin_t);
 
 	sf = (struct signal_frame __user *)
 		get_sigframe(&ka->sa, regs, sigframe_size);
@@ -334,8 +284,7 @@ static int setup_frame(struct k_sigaction *ka, struct pt_regs *regs,
 	if (invalid_frame_pointer(sf, sigframe_size))
 		goto sigill_and_return;
 
-	if (current_thread_info()->w_saved != 0)
-		goto sigill_and_return;
+	tail = sf + 1;
 
 	/* 2. Save the current process state */
 	err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
@@ -343,17 +292,34 @@ static int setup_frame(struct k_sigaction *ka, struct pt_regs *regs,
 	err |= __put_user(0, &sf->extra_size);
 
 	if (used_math()) {
-		err |= save_fpu_state(regs, &sf->fpu_state);
-		err |= __put_user(&sf->fpu_state, &sf->fpu_save);
+		__siginfo_fpu_t __user *fp = tail;
+		tail += sizeof(*fp);
+		err |= save_fpu_state(regs, fp);
+		err |= __put_user(fp, &sf->fpu_save);
 	} else {
 		err |= __put_user(0, &sf->fpu_save);
 	}
+	if (wsaved) {
+		__siginfo_rwin_t __user *rwp = tail;
+		tail += sizeof(*rwp);
+		err |= save_rwin_state(wsaved, rwp);
+		err |= __put_user(rwp, &sf->rwin_save);
+	} else {
+		err |= __put_user(0, &sf->rwin_save);
+	}
 
 	err |= __put_user(oldset->sig[0], &sf->info.si_mask);
 	err |= __copy_to_user(sf->extramask, &oldset->sig[1],
 			      (_NSIG_WORDS - 1) * sizeof(unsigned int));
-	err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
-			      sizeof(struct reg_window32));
+	if (!wsaved) {
+		err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
+				      sizeof(struct reg_window32));
+	} else {
+		struct reg_window32 *rp;
+
+		rp = &current_thread_info()->reg_window[wsaved - 1];
+		err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
+	}
 	if (err)
 		goto sigsegv;
 	
@@ -399,21 +365,24 @@ static int setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
 			  int signo, sigset_t *oldset, siginfo_t *info)
 {
 	struct rt_signal_frame __user *sf;
-	int sigframe_size;
+	int sigframe_size, wsaved;
+	void __user *tail;
 	unsigned int psr;
 	int err;
 
 	synchronize_user_stack();
-	sigframe_size = RT_ALIGNEDSZ;
-	if (!used_math())
-		sigframe_size -= sizeof(__siginfo_fpu_t);
+	wsaved = current_thread_info()->w_saved;
+	sigframe_size = sizeof(*sf);
+	if (used_math())
+		sigframe_size += sizeof(__siginfo_fpu_t);
+	if (wsaved)
+		sigframe_size += sizeof(__siginfo_rwin_t);
 	sf = (struct rt_signal_frame __user *)
 		get_sigframe(&ka->sa, regs, sigframe_size);
 	if (invalid_frame_pointer(sf, sigframe_size))
 		goto sigill;
-	if (current_thread_info()->w_saved != 0)
-		goto sigill;
 
+	tail = sf + 1;
 	err  = __put_user(regs->pc, &sf->regs.pc);
 	err |= __put_user(regs->npc, &sf->regs.npc);
 	err |= __put_user(regs->y, &sf->regs.y);
@@ -425,11 +394,21 @@ static int setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
 	err |= __put_user(0, &sf->extra_size);
 
 	if (psr & PSR_EF) {
-		err |= save_fpu_state(regs, &sf->fpu_state);
-		err |= __put_user(&sf->fpu_state, &sf->fpu_save);
+		__siginfo_fpu_t *fp = tail;
+		tail += sizeof(*fp);
+		err |= save_fpu_state(regs, fp);
+		err |= __put_user(fp, &sf->fpu_save);
 	} else {
 		err |= __put_user(0, &sf->fpu_save);
 	}
+	if (wsaved) {
+		__siginfo_rwin_t *rwp = tail;
+		tail += sizeof(*rwp);
+		err |= save_rwin_state(wsaved, rwp);
+		err |= __put_user(rwp, &sf->rwin_save);
+	} else {
+		err |= __put_user(0, &sf->rwin_save);
+	}
 	err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
 	
 	/* Setup sigaltstack */
@@ -437,8 +416,15 @@ static int setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
 	err |= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &sf->stack.ss_flags);
 	err |= __put_user(current->sas_ss_size, &sf->stack.ss_size);
 	
-	err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
-			      sizeof(struct reg_window32));
+	if (!wsaved) {
+		err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
+				      sizeof(struct reg_window32));
+	} else {
+		struct reg_window32 *rp;
+
+		rp = &current_thread_info()->reg_window[wsaved - 1];
+		err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
+	}
 
 	err |= copy_siginfo_to_user(&sf->info, info);