Re-introduction of sigcontext.

struct sigcontext and ucontext_t/mcontext_t are defined in such
a way that both (ie struct sigcontext and ucontext_t) can be
passed on to sigreturn. The signal handler is still given a
ucontext_t for maximum flexibility.

For backward compatibility sigreturn restores the state for the
alternate signal stack from sigcontext.sc_onstack and not from
ucontext_t.uc_stack. A good way to determine which value the
application has set and thus which value to use, is still open
for discussion.

NOTE: This change should only affect those binaries that use
      sigcontext and/or ucontext_t. In the source tree itself
      this is only doscmd. Recompilation is required for those
      applications.

This commit also fixes a lot of style bugs without hopefully
adding new ones.

NOTE: struct sigaltstack.ss_size now has type size_t again. For
      some reason I changed that into unsigned int.

Parts submitted by: bde
sigaltstack bug found by: bde

4 files changed, 82 insertions, 23 deletions

diff --git a/sys/alpha/alpha/machdep.c b/sys/alpha/alpha/machdep.c
index 85262fe..ce72dce 100644
--- a/sys/alpha/alpha/machdep.c
+++ b/sys/alpha/alpha/machdep.c
@@ -1269,7 +1269,7 @@ sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
 	struct trapframe *frame;
 	struct sigacts *psp;
 	struct sigframe sf, *sfp;
-	int rndfsize;
+	int onstack, rndfsize;
 
 	p = curproc;
 
@@ -1280,13 +1280,26 @@ sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
 
 	frame = p->p_md.md_tf;
 	psp = p->p_sigacts;
+	onstack = (psp->ps_sigstk.ss_flags & SS_ONSTACK) ? 1 : 0;
 	rndfsize = ((sizeof(sf) + 15) / 16) * 16;
 
 	/* save user context */
 	bzero(&sf, sizeof(struct sigframe));
 	sf.sf_uc.uc_sigmask = *mask;
 	sf.sf_uc.uc_stack = psp->ps_sigstk;
-	sf.sf_uc.uc_mcontext.mc_tf = *frame;
+	sf.sf_uc.uc_mcontext.mc_onstack = onstack;
+
+	fill_regs(p, (struct reg *)sf.sf_uc.uc_mcontext.mc_regs);
+	sf.sf_uc.uc_mcontext.mc_regs[R_SP] = alpha_pal_rdusp();
+	sf.sf_uc.uc_mcontext.mc_regs[R_ZERO] = 0xACEDBADE;   /* magic number */
+	sf.sf_uc.uc_mcontext.mc_regs[R_PS] = frame->tf_regs[FRAME_PS];
+	sf.sf_uc.uc_mcontext.mc_regs[R_PC] = frame->tf_regs[FRAME_PC];
+	sf.sf_uc.uc_mcontext.mc_regs[R_TRAPARG_A0] =
+	    frame->tf_regs[FRAME_TRAPARG_A0];
+	sf.sf_uc.uc_mcontext.mc_regs[R_TRAPARG_A1] =
+	    frame->tf_regs[FRAME_TRAPARG_A1];
+	sf.sf_uc.uc_mcontext.mc_regs[R_TRAPARG_A2] =
+	    frame->tf_regs[FRAME_TRAPARG_A2];
 
 	/*
 	 * Allocate and validate space for the signal handler
@@ -1295,8 +1308,7 @@ sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
 	 * will fail if the process has not already allocated
 	 * the space with a `brk'.
 	 */
-	if ((psp->ps_flags & SAS_ALTSTACK) != 0 &&
-	    (psp->ps_sigstk.ss_flags & SS_ONSTACK) == 0 &&
+	if ((psp->ps_flags & SAS_ALTSTACK) != 0 && !onstack &&
 	    SIGISMEMBER(psp->ps_sigonstack, sig)) {
 		sfp = (struct sigframe *)((caddr_t)psp->ps_sigstk.ss_sp +
 		    psp->ps_sigstk.ss_size - rndfsize);
@@ -1328,8 +1340,6 @@ sendsig(sig_t catcher, int sig, sigset_t *mask, u_long code)
 		return;
 	}
 
-	sf.sf_uc.uc_mcontext.mc_tf.tf_regs[FRAME_SP] = alpha_pal_rdusp();
-
 	/* save the floating-point state, if necessary, then copy it. */
 	if (p == fpcurproc) {
 		alpha_pal_wrfen(1);
@@ -1418,6 +1428,10 @@ osigreturn(struct proc *p,
 	    copyin((caddr_t)scp, (caddr_t)&ksc, sizeof ksc))
 		return (EINVAL);
 
+	/*
+	 * XXX - Should we do this. What if we get a "handcrafted"
+	 * but valid sigcontext that hasn't the magic number?
+	 */
 	if (ksc.sc_regs[R_ZERO] != 0xACEDBADE)		/* magic number */
 		return (EINVAL);
 	/*
@@ -1464,6 +1478,7 @@ sigreturn(struct proc *p,
 {
 	ucontext_t uc, *ucp;
 	struct pcb *pcb;
+	unsigned long val;
 
 	ucp = uap->sigcntxp;
 
@@ -1491,13 +1506,18 @@ sigreturn(struct proc *p,
 	/*
 	 * Restore the user-supplied information
 	 */
-	*p->p_md.md_tf = uc.uc_mcontext.mc_tf;
-	p->p_md.md_tf->tf_regs[FRAME_PS] |= ALPHA_PSL_USERSET;
-	p->p_md.md_tf->tf_regs[FRAME_PS] &= ~ALPHA_PSL_USERCLR;
-	pcb->pcb_hw.apcb_usp = p->p_md.md_tf->tf_regs[FRAME_SP];
-	alpha_pal_wrusp(pcb->pcb_hw.apcb_usp);
+	set_regs(p, (struct reg *)uc.uc_mcontext.mc_regs);
+	val = (uc.uc_mcontext.mc_regs[R_PS] | ALPHA_PSL_USERSET) &
+	    ~ALPHA_PSL_USERCLR;
+	p->p_md.md_tf->tf_regs[FRAME_PS] = val;
+	p->p_md.md_tf->tf_regs[FRAME_PC] = uc.uc_mcontext.mc_regs[R_PC];
+	alpha_pal_wrusp(uc.uc_mcontext.mc_regs[R_SP]);
+
+	if (uc.uc_mcontext.mc_onstack & 1)
+		p->p_sigacts->ps_sigstk.ss_flags |= SS_ONSTACK;
+	else
+		p->p_sigacts->ps_sigstk.ss_flags &= ~SS_ONSTACK;
 
-	p->p_sigacts->ps_sigstk = uc.uc_stack;
 	p->p_sigmask = uc.uc_sigmask;
 	SIG_CANTMASK(p->p_sigmask);
 
diff --git a/sys/alpha/include/reg.h b/sys/alpha/include/reg.h
index 341a396..879aeed 100644
--- a/sys/alpha/include/reg.h
+++ b/sys/alpha/include/reg.h
@@ -73,6 +73,15 @@
 #define	R_SP	30
 #define	R_ZERO	31
 
+/*
+ * Register extensions used in mcontext_t
+ */
+#define	R_PS		32
+#define	R_PC		33
+#define	R_TRAPARG_A0	34
+#define	R_TRAPARG_A1	35
+#define	R_TRAPARG_A2	36
+
 struct reg {
 	u_int64_t	r_regs[32];
 };
diff --git a/sys/alpha/include/signal.h b/sys/alpha/include/signal.h
index 90a5a39..2e01864 100644
--- a/sys/alpha/include/signal.h
+++ b/sys/alpha/include/signal.h
@@ -32,6 +32,7 @@
 #define	_ALPHA_SIGNAL_H_
 
 typedef long	sig_atomic_t;
+
 #ifndef _ANSI_SOURCE
 
 /*
@@ -52,7 +53,6 @@ struct  osigcontext {
 	long	sc_pc;                  /* pc to restore */
 	long	sc_ps;			/* ps to restore */
 	unsigned long sc_regs[32];	/* integer register set (see above) */
-#define	sc_sp	sc_regs[R_SP]
 	long	sc_ownedfp;		/* fp has been used */
 	unsigned long sc_fpregs[32];	/* FP register set (see above) */
 	unsigned long sc_fpcr;		/* FP control register (see above) */
@@ -65,5 +65,29 @@ struct  osigcontext {
 	long	sc_xxx2[3];		/* sc_fp_trap_pc, sc_fp_trigger_sum, sc_fp_trigger_inst */
 };
 
+/*
+ * The sequence of the fields should match those in
+ * mcontext_t. Keep them in sync!
+ */
+struct	sigcontext {
+	sigset_t sc_mask;		/* signal mask to restore */
+	long	sc_onstack;             /* sigstack state to restore */
+	unsigned long sc_regs[32];	/* integer register set (see above) */
+	long	sc_ps;			/* ps to restore */
+	long	sc_pc;                  /* pc to restore */
+	unsigned long sc_traparg_a0;	/* a0 argument to trap at exception */
+	unsigned long sc_traparg_a1;	/* a1 argument to trap at exception */
+	unsigned long sc_traparg_a2;	/* a2 argument to trap at exception */
+	unsigned long sc_fpregs[32];	/* FP register set (see above) */
+	unsigned long sc_fpcr;		/* FP control register (see above) */
+	unsigned long sc_fp_control;	/* FP software control word */
+	long	sc_ownedfp;		/* fp has been used */
+	long	sc_xxx1[2];		/* sc_ssize, sc_sbase on DUX */
+	long	sc_xxx2[3];		/* sc_fp_trap_pc, sc_fp_trigger_sum, sc_fp_trigger_inst */
+	long	sc_reserved[2];		/* XXX */
+};
+
+#define	sc_sp	sc_regs[R_SP]
+
 #endif /* !_ANSI_SOURCE */
 #endif /* !_ALPHA_SIGNAL_H_*/
diff --git a/sys/alpha/include/ucontext.h b/sys/alpha/include/ucontext.h
index 66b9e51..40a9037 100644
--- a/sys/alpha/include/ucontext.h
+++ b/sys/alpha/include/ucontext.h
@@ -29,18 +29,24 @@
  */
 
 #ifndef _MACHINE_UCONTEXT_H_
-#define _MACHINE_UCONTEXT_H_ 1
+#define	_MACHINE_UCONTEXT_H_
 
 #include <machine/frame.h>
 
-typedef struct {
-	struct trapframe mc_tf;
-	unsigned long	mc_fpregs[32];
-	unsigned long	mc_fpcr;
-	unsigned long	mc_fp_control;
-	unsigned long	mc_apcb_usp;
-	long		mc_ownedfp;
-	long		__spare__[8];
+typedef struct __mcontext {
+	/*
+	 * These fields must match the definition
+	 * of struct sigcontext. That way we can support
+	 * struct sigcontext and ucontext_t at the same
+	 * time.
+	 */
+	long	mc_onstack;		/* XXX - sigcontext compat. */
+	unsigned long mc_regs[37];
+	unsigned long mc_fpregs[32];
+	unsigned long mc_fpcr;
+	unsigned long mc_fp_control;
+	long	mc_ownedfp;
+	long	__spare__[7];
 } mcontext_t;
 
-#endif /* _MACHINE_UCONTEXT_H_ */
+#endif /* !_MACHINE_UCONTEXT_H_ */