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, 47 insertions, 61 deletions

diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c
index 006fe4515886..47509df3b893 100644
--- a/arch/sparc/kernel/signal_64.c
+++ b/arch/sparc/kernel/signal_64.c
@@ -34,6 +34,7 @@
 
 #include "entry.h"
 #include "systbls.h"
+#include "sigutil.h"
 
 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 
@@ -236,7 +237,7 @@ struct rt_signal_frame {
 	__siginfo_fpu_t __user	*fpu_save;
 	stack_t			stack;
 	sigset_t		mask;
-	__siginfo_fpu_t		fpu_state;
+	__siginfo_rwin_t	*rwin_save;
 };
 
 static long _sigpause_common(old_sigset_t set)
@@ -266,33 +267,12 @@ asmlinkage long 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)
-{
-	unsigned long *fpregs = current_thread_info()->fpregs;
-	unsigned long fprs;
-	int err;
-
-	err = __get_user(fprs, &fpu->si_fprs);
-	fprs_write(0);
-	regs->tstate &= ~TSTATE_PEF;
-	if (fprs & FPRS_DL)
-		err |= copy_from_user(fpregs, &fpu->si_float_regs[0],
-		       	       (sizeof(unsigned int) * 32));
-	if (fprs & FPRS_DU)
-		err |= copy_from_user(fpregs+16, &fpu->si_float_regs[32],
-		       	       (sizeof(unsigned int) * 32));
-	err |= __get_user(current_thread_info()->xfsr[0], &fpu->si_fsr);
-	err |= __get_user(current_thread_info()->gsr[0], &fpu->si_gsr);
-	current_thread_info()->fpsaved[0] |= fprs;
-	return err;
-}
-
 void do_rt_sigreturn(struct pt_regs *regs)
 {
 	struct rt_signal_frame __user *sf;
 	unsigned long tpc, tnpc, tstate;
 	__siginfo_fpu_t __user *fpu_save;
+	__siginfo_rwin_t __user *rwin_save;
 	sigset_t set;
 	int err;
 
@@ -325,8 +305,8 @@ void do_rt_sigreturn(struct pt_regs *regs)
 	regs->tstate |= (tstate & (TSTATE_ASI | TSTATE_ICC | TSTATE_XCC));
 
 	err |= __get_user(fpu_save, &sf->fpu_save);
-	if (fpu_save)
-		err |= restore_fpu_state(regs, &sf->fpu_state);
+	if (!err && fpu_save)
+		err |= restore_fpu_state(regs, fpu_save);
 
 	err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
 	err |= do_sigaltstack(&sf->stack, NULL, (unsigned long)sf);
@@ -334,6 +314,12 @@ void do_rt_sigreturn(struct pt_regs *regs)
 	if (err)
 		goto segv;
 
+	err |= __get_user(rwin_save, &sf->rwin_save);
+	if (!err && rwin_save) {
+		if (restore_rwin_state(rwin_save))
+			goto segv;
+	}
+
 	regs->tpc = tpc;
 	regs->tnpc = tnpc;
 
@@ -351,34 +337,13 @@ segv:
 }
 
 /* Checks if the fp is valid */
-static int invalid_frame_pointer(void __user *fp, int fplen)
+static int invalid_frame_pointer(void __user *fp)
 {
 	if (((unsigned long) fp) & 15)
 		return 1;
 	return 0;
 }
 
-static inline int
-save_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
-{
-	unsigned long *fpregs = current_thread_info()->fpregs;
-	unsigned long fprs;
-	int err = 0;
-	
-	fprs = current_thread_info()->fpsaved[0];
-	if (fprs & FPRS_DL)
-		err |= copy_to_user(&fpu->si_float_regs[0], fpregs,
-				    (sizeof(unsigned int) * 32));
-	if (fprs & FPRS_DU)
-		err |= copy_to_user(&fpu->si_float_regs[32], fpregs+16,
-				    (sizeof(unsigned int) * 32));
-	err |= __put_user(current_thread_info()->xfsr[0], &fpu->si_fsr);
-	err |= __put_user(current_thread_info()->gsr[0], &fpu->si_gsr);
-	err |= __put_user(fprs, &fpu->si_fprs);
-
-	return err;
-}
-
 static inline void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, unsigned long framesize)
 {
 	unsigned long sp = regs->u_regs[UREG_FP] + STACK_BIAS;
@@ -414,34 +379,48 @@ 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, err;
+	int wsaved, err, sf_size;
+	void __user *tail;
 
 	/* 1. Make sure everything is clean */
 	synchronize_user_stack();
 	save_and_clear_fpu();
 	
-	sigframe_size = sizeof(struct rt_signal_frame);
-	if (!(current_thread_info()->fpsaved[0] & FPRS_FEF))
-		sigframe_size -= sizeof(__siginfo_fpu_t);
+	wsaved = get_thread_wsaved();
 
+	sf_size = sizeof(struct rt_signal_frame);
+	if (current_thread_info()->fpsaved[0] & FPRS_FEF)
+		sf_size += sizeof(__siginfo_fpu_t);
+	if (wsaved)
+		sf_size += sizeof(__siginfo_rwin_t);
 	sf = (struct rt_signal_frame __user *)
-		get_sigframe(ka, regs, sigframe_size);
-	
-	if (invalid_frame_pointer (sf, sigframe_size))
-		goto sigill;
+		get_sigframe(ka, regs, sf_size);
 
-	if (get_thread_wsaved() != 0)
+	if (invalid_frame_pointer (sf))
 		goto sigill;
 
+	tail = (sf + 1);
+
 	/* 2. Save the current process state */
 	err = copy_to_user(&sf->regs, regs, sizeof (*regs));
 
 	if (current_thread_info()->fpsaved[0] & FPRS_FEF) {
-		err |= save_fpu_state(regs, &sf->fpu_state);
-		err |= __put_user((u64)&sf->fpu_state, &sf->fpu_save);
+		__siginfo_fpu_t __user *fpu_save = tail;
+		tail += sizeof(__siginfo_fpu_t);
+		err |= save_fpu_state(regs, fpu_save);
+		err |= __put_user((u64)fpu_save, &sf->fpu_save);
 	} else {
 		err |= __put_user(0, &sf->fpu_save);
 	}
+	if (wsaved) {
+		__siginfo_rwin_t __user *rwin_save = tail;
+		tail += sizeof(__siginfo_rwin_t);
+		err |= save_rwin_state(wsaved, rwin_save);
+		err |= __put_user((u64)rwin_save, &sf->rwin_save);
+		set_thread_wsaved(0);
+	} else {
+		err |= __put_user(0, &sf->rwin_save);
+	}
 	
 	/* Setup sigaltstack */
 	err |= __put_user(current->sas_ss_sp, &sf->stack.ss_sp);
@@ -450,10 +429,17 @@ setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
 
 	err |= copy_to_user(&sf->mask, oldset, sizeof(sigset_t));
 
-	err |= copy_in_user((u64 __user *)sf,
-			    (u64 __user *)(regs->u_regs[UREG_FP]+STACK_BIAS),
-			    sizeof(struct reg_window));
+	if (!wsaved) {
+		err |= copy_in_user((u64 __user *)sf,
+				    (u64 __user *)(regs->u_regs[UREG_FP] +
+						   STACK_BIAS),
+				    sizeof(struct reg_window));
+	} else {
+		struct reg_window *rp;
 
+		rp = &current_thread_info()->reg_window[wsaved - 1];
+		err |= copy_to_user(sf, rp, sizeof(struct reg_window));
+	}
 	if (info)
 		err |= copy_siginfo_to_user(&sf->info, info);
 	else {