Make MINSIGSTKSZ machine dependent, and have the sigaltstack

syscall compare against a variable sv_minsigstksz in struct
sysentvec as to properly take the size of the machine- and
ABI dependent struct sigframe into account.

The SVR4 and iBCS2 modules continue to have a minsigstksz of
8192 to preserve behavior. The real values (if different) are
not known at this time. Other ABI modules use the real
values.

The native MINSIGSTKSZ is now defined as follows:

Arch		MINSIGSTKSZ
----		-----------
alpha		    4096
i386		    2048
ia64		   12288

Reviewed by: mjacob
Suggested by: bde

20 files changed, 56 insertions, 19 deletions

diff --git a/sys/alpha/include/signal.h b/sys/alpha/include/signal.h
index 2e01864..02a4bfd 100644
--- a/sys/alpha/include/signal.h
+++ b/sys/alpha/include/signal.h
@@ -36,6 +36,12 @@ typedef long	sig_atomic_t;
 #ifndef _ANSI_SOURCE
 
 /*
+ * Minimum signal stack size. The current signal frame
+ * for Alpha is 808 bytes large.
+ */
+#define	MINSIGSTKSZ	(1024 * 4)
+
+/*
  * Information pushed on stack when a signal is delivered.
  * This is used by the kernel to restore state following
  * execution of the signal handler.  It is also made available
diff --git a/sys/alpha/linux/linux.h b/sys/alpha/linux/linux.h
index c441cc2..507289b 100644
--- a/sys/alpha/linux/linux.h
+++ b/sys/alpha/linux/linux.h
@@ -159,6 +159,8 @@ struct linux_new_utsname {
 #define	LINUX_SIGISMEMBER(set, sig)	SIGISMEMBER(set, sig)
 #define	LINUX_SIGADDSET(set, sig)	SIGADDSET(set, sig)
 
+#define	LINUX_MINSIGSTKSZ	4096
+
 typedef void	(*linux_handler_t)(int);
 typedef u_long	linux_osigset_t;
 
diff --git a/sys/alpha/linux/linux_sysvec.c b/sys/alpha/linux/linux_sysvec.c
index 50ec18f..8b4e13c 100644
--- a/sys/alpha/linux/linux_sysvec.c
+++ b/sys/alpha/linux/linux_sysvec.c
@@ -186,7 +186,8 @@ struct sysentvec elf_linux_sysvec = {
 	0,
 	"Linux ELF",
 	elf_coredump,
-	exec_linux_imgact_try
+	exec_linux_imgact_try,
+	LINUX_MINSIGSTKSZ
 };
 
 static Elf64_Brandinfo linux_brand = {
diff --git a/sys/alpha/osf1/osf1.h b/sys/alpha/osf1/osf1.h
index 7628bf0..bc91295 100644
--- a/sys/alpha/osf1/osf1.h
+++ b/sys/alpha/osf1/osf1.h
@@ -31,6 +31,7 @@ extern struct sysent osf1_sysent[];
 extern int bsd_to_osf1_sig[];
 extern int bsd_to_osf1_errno[];
 
+#define	OSF1_MINSIGSTKSZ	4096
 
 /* osf/1 ioctls */
 #define	OSF1_IOCPARM_MASK	0x1fff	/* parameter length, at most 13 bits */
diff --git a/sys/alpha/osf1/osf1_sysvec.c b/sys/alpha/osf1/osf1_sysvec.c
index 45e9125..b89375a 100644
--- a/sys/alpha/osf1/osf1_sysvec.c
+++ b/sys/alpha/osf1/osf1_sysvec.c
@@ -74,8 +74,9 @@ struct sysentvec osf1_sysvec = {
         &osf1_szsigcode,	/* use generic trampoline size */
         0,			/* prepsyscall */
 	"OSF/1 ECOFF",
-	NULL			/* we don't have an ECOFF coredump function */
-	
+	NULL,			/* we don't have an ECOFF coredump function */
+	NULL,
+	OSF1_MINSIGSTKSZ
 };
 
 /*
diff --git a/sys/amd64/include/signal.h b/sys/amd64/include/signal.h
index e3f1b19..1e91f60 100644
--- a/sys/amd64/include/signal.h
+++ b/sys/amd64/include/signal.h
@@ -45,6 +45,12 @@ typedef int sig_atomic_t;
 
 #if !defined(_ANSI_SOURCE) && !defined(_POSIX_SOURCE)
 
+/*
+ * Minimum signal stack size. The current signal frame
+ * for i386 is 408 bytes large.
+ */
+#define	MINSIGSTKSZ	(512 * 4)
+
 #include <machine/trap.h>	/* codes for SIGILL, SIGFPE */
 
 /*
diff --git a/sys/compat/svr4/svr4_signal.h b/sys/compat/svr4/svr4_signal.h
index 1549c83..f7b0b52 100644
--- a/sys/compat/svr4/svr4_signal.h
+++ b/sys/compat/svr4/svr4_signal.h
@@ -132,6 +132,8 @@ struct svr4_sigaltstack {
 #define SVR4_SS_DISABLE		0x00000002
 #define	SVR4_SS_ALLBITS		0x00000003
 
+#define	SVR4_MINSIGSTKSZ	8192
+
 void bsd_to_svr4_sigaltstack __P((const struct sigaltstack *, struct svr4_sigaltstack *));
 void bsd_to_svr4_sigset __P((const sigset_t *, svr4_sigset_t *));
 void svr4_to_bsd_sigaltstack __P((const struct svr4_sigaltstack *, struct sigaltstack *));
diff --git a/sys/compat/svr4/svr4_sysvec.c b/sys/compat/svr4/svr4_sysvec.c
index 9690a99..f314d1d 100644
--- a/sys/compat/svr4/svr4_sysvec.c
+++ b/sys/compat/svr4/svr4_sysvec.c
@@ -177,7 +177,9 @@ struct sysentvec svr4_sysvec = {
   &svr4_szsigcode,
   NULL,
   "SVR4",
-  elf_coredump
+  elf_coredump,
+  NULL,
+  SVR4_MINSIGSTKSZ
 };
 
 Elf32_Brandinfo svr4_brand = {
diff --git a/sys/i386/ibcs2/ibcs2_signal.h b/sys/i386/ibcs2/ibcs2_signal.h
index 2eadf6c..21df087 100644
--- a/sys/i386/ibcs2/ibcs2_signal.h
+++ b/sys/i386/ibcs2/ibcs2_signal.h
@@ -103,6 +103,8 @@ struct ibcs2_sigaction {
 /* sa_flags */
 #define IBCS2_SA_NOCLDSTOP	1
 
+#define	IBCS2_MINSIGSTKSZ	8192
+
 extern int bsd_to_ibcs2_sig[];
 
 #endif /* _IBCS2_SIGNAL_H */
diff --git a/sys/i386/ibcs2/ibcs2_sysvec.c b/sys/i386/ibcs2/ibcs2_sysvec.c
index 027c990..3f08212 100644
--- a/sys/i386/ibcs2/ibcs2_sysvec.c
+++ b/sys/i386/ibcs2/ibcs2_sysvec.c
@@ -62,7 +62,9 @@ struct sysentvec ibcs2_svr3_sysvec = {
 	&szsigcode,	/* use generic trampoline size */
 	0,		/* prepsyscall */
 	"IBCS2 COFF",
-	NULL		/* we don't have a COFF coredump function */
+	NULL,		/* we don't have a COFF coredump function */
+	NULL,
+	IBCS2_MINSIGSTKSZ
 };
 
 /*
diff --git a/sys/i386/include/signal.h b/sys/i386/include/signal.h
index e3f1b19..1e91f60 100644
--- a/sys/i386/include/signal.h
+++ b/sys/i386/include/signal.h
@@ -45,6 +45,12 @@ typedef int sig_atomic_t;
 
 #if !defined(_ANSI_SOURCE) && !defined(_POSIX_SOURCE)
 
+/*
+ * Minimum signal stack size. The current signal frame
+ * for i386 is 408 bytes large.
+ */
+#define	MINSIGSTKSZ	(512 * 4)
+
 #include <machine/trap.h>	/* codes for SIGILL, SIGFPE */
 
 /*
diff --git a/sys/i386/linux/linux_machdep.c b/sys/i386/linux/linux_machdep.c
index 6af8832..b95ce4c 100644
--- a/sys/i386/linux/linux_machdep.c
+++ b/sys/i386/linux/linux_machdep.c
@@ -668,8 +668,7 @@ linux_sigaltstack(p, uap)
 
 		ss = stackgap_alloc(&sg, sizeof(stack_t));
 		ss->ss_sp = lss.ss_sp;
-		ss->ss_size = (lss.ss_size >= LINUX_MINSIGSTKSZ &&
-		    lss.ss_size < MINSIGSTKSZ) ? MINSIGSTKSZ : lss.ss_size;
+		ss->ss_size = lss.ss_size;
 		ss->ss_flags = linux_to_bsd_sigaltstack(lss.ss_flags);
 	}
 	oss = (uap->uoss != NULL)
@@ -686,8 +685,6 @@ linux_sigaltstack(p, uap)
 		lss.ss_flags = bsd_to_linux_sigaltstack(oss->ss_flags);
 		error = copyout(&lss, uap->uoss, sizeof(linux_stack_t));
 	}
-	if (!error && (ss != NULL) && (lss.ss_size < ss->ss_size))
-		p->p_sigstk.ss_size = lss.ss_size;
 
 	return (error);
 }
diff --git a/sys/i386/linux/linux_sysvec.c b/sys/i386/linux/linux_sysvec.c
index ee6ee7e..9129efb 100644
--- a/sys/i386/linux/linux_sysvec.c
+++ b/sys/i386/linux/linux_sysvec.c
@@ -633,15 +633,13 @@ linux_rt_sigreturn(p, args)
 	regs->tf_esp    = context->sc_esp_at_signal;
 	regs->tf_ss     = context->sc_ss;
 
-
 	/*
 	 * call sigaltstack & ignore results..
 	 */
 	ss = stackgap_alloc(&sg, sizeof(stack_t));
 	lss = &uc.uc_stack;
 	ss->ss_sp = lss->ss_sp;
-	ss->ss_size = (lss->ss_size >= LINUX_MINSIGSTKSZ &&
-	    lss->ss_size < MINSIGSTKSZ) ? MINSIGSTKSZ : lss->ss_size;
+	ss->ss_size = lss->ss_size;
 	ss->ss_flags = linux_to_bsd_sigaltstack(lss->ss_flags);
 
 #ifdef DEBUG
@@ -726,7 +724,8 @@ struct sysentvec linux_sysvec = {
 	linux_prepsyscall,
 	"Linux a.out",
 	aout_coredump,
-	exec_linux_imgact_try
+	exec_linux_imgact_try,
+	LINUX_MINSIGSTKSZ
 };
 
 struct sysentvec elf_linux_sysvec = {
@@ -745,7 +744,8 @@ struct sysentvec elf_linux_sysvec = {
 	linux_prepsyscall,
 	"Linux ELF",
 	elf_coredump,
-	exec_linux_imgact_try
+	exec_linux_imgact_try,
+	LINUX_MINSIGSTKSZ
 };
 
 static Elf32_Brandinfo linux_brand = {
diff --git a/sys/ia64/include/signal.h b/sys/ia64/include/signal.h
index e1602e4..268836c 100644
--- a/sys/ia64/include/signal.h
+++ b/sys/ia64/include/signal.h
@@ -35,6 +35,12 @@ typedef long	sig_atomic_t;
 
 #ifndef _ANSI_SOURCE
 
+/*
+ * Minimum signal stack size. The current signal frame
+ * for IA-64 is 2656 bytes large.
+ */
+#define MINSIGSTKSZ     (3072 * 4)
+
 #ifndef _IA64_FPREG_DEFINED
 
 struct ia64_fpreg {
diff --git a/sys/kern/imgact_aout.c b/sys/kern/imgact_aout.c
index 80ecc0c..e27a80c 100644
--- a/sys/kern/imgact_aout.c
+++ b/sys/kern/imgact_aout.c
@@ -69,7 +69,9 @@ struct sysentvec aout_sysvec = {
 	&szsigcode,
 	0,
 	"FreeBSD a.out",
-	aout_coredump
+	aout_coredump,
+	NULL,
+	MINSIGSTKSZ
 };
 
 static int
diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c
index 069bc9a..9706d67 100644
--- a/sys/kern/imgact_elf.c
+++ b/sys/kern/imgact_elf.c
@@ -99,7 +99,9 @@ struct sysentvec elf_freebsd_sysvec = {
         &szsigcode,
         0,
 	"FreeBSD ELF",
-	elf_coredump
+	elf_coredump,
+	NULL,
+	MINSIGSTKSZ
 };
 
 static Elf_Brandinfo freebsd_brand_info = {
diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 00624d4..af7a32f 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -830,7 +830,7 @@ sigaltstack(p, uap)
 		p->p_sigstk.ss_flags = ss.ss_flags;
 		return (0);
 	}
-	if (ss.ss_size < MINSIGSTKSZ)
+	if (ss.ss_size < p->p_sysent->sv_minsigstksz)
 		return (ENOMEM);
 	p->p_flag |= P_ALTSTACK;
 	p->p_sigstk = ss;
diff --git a/sys/sys/_sigset.h b/sys/sys/_sigset.h
index 2e405a2..e3bef90 100644
--- a/sys/sys/_sigset.h
+++ b/sys/sys/_sigset.h
@@ -238,7 +238,6 @@ typedef struct sigaltstack {
 
 #define	SS_ONSTACK	0x0001	/* take signal on alternate stack */
 #define	SS_DISABLE	0x0004	/* disable taking signals on alternate stack */
-#define	MINSIGSTKSZ	8192			/* minimum allowable stack */
 #define	SIGSTKSZ	(MINSIGSTKSZ + 32768)	/* recommended stack size */
 
 /* Have enough typedefs for this now.  XXX */
diff --git a/sys/sys/signal.h b/sys/sys/signal.h
index 2e405a2..e3bef90 100644
--- a/sys/sys/signal.h
+++ b/sys/sys/signal.h
@@ -238,7 +238,6 @@ typedef struct sigaltstack {
 
 #define	SS_ONSTACK	0x0001	/* take signal on alternate stack */
 #define	SS_DISABLE	0x0004	/* disable taking signals on alternate stack */
-#define	MINSIGSTKSZ	8192			/* minimum allowable stack */
 #define	SIGSTKSZ	(MINSIGSTKSZ + 32768)	/* recommended stack size */
 
 /* Have enough typedefs for this now.  XXX */
diff --git a/sys/sys/sysent.h b/sys/sys/sysent.h
index fc06f77..93d356b 100644
--- a/sys/sys/sysent.h
+++ b/sys/sys/sysent.h
@@ -80,6 +80,7 @@ struct sysentvec {
 					    off_t));
 					/* function to dump core, or NULL */
 	int		(*sv_imgact_try) __P((struct image_params *));
+	int		sv_minsigstksz;	/* minimum signal stack size */
 };
 
 #ifdef _KERNEL