setcontext and signal mask on Linux/ia64

[Peter A. Buhr]

Our team has discovered two bugs in the implementation of setcontext
for Linux on the ia64.

Bug 1: setcontext does not install signal mask

The first section of the setcontext function inlines a call to the
rt_sigprocmask syscall.  It only passes three arguments, however,
rt_sigprocmask expects a fourth argument, which must be sizeof(sigset_t).  This
missing argument causes rt_sigprocmask to fail with EINVAL, but this error is
ignored by setcontext.

Bug 2: setcontext installs the wrong value as signal mask

The inlined call to rt_sigprocmask uses the hardcoded offset SC_MASK
(0x9d0) to get the signal mask for the new context from the input
struct sigcontext.  But offsetof( struct sigcontext, sc_mask ) is
0xa50, so the value of sc_rbs_base (which happens to be at offset
0x9d0) is used instead.

The following patch fixes both problems.

diff -Nru glibc-2.3.2/sysdeps/unix/sysv/linux/ia64/setcontext.S 
glibc-2.3.2-work/sysdeps/unix/sysv/linux/ia64/setcontext.S
- --- glibc-2.3.2/sysdeps/unix/sysv/linux/ia64/setcontext.S     Sat Jul  7 
15:21:34 2001
+++ glibc-2.3.2-work/sysdeps/unix/sysv/linux/ia64/setcontext.S  Thu May  1 
11:50:08 2003
@@ -32,7 +32,7 @@
   other than the PRESERVED state.  */
 
 ENTRY(__setcontext)
- -     alloc r16 = ar.pfs, 1, 0, 3, 0
+       alloc r16 = ar.pfs, 1, 0, 4, 0
 
        // sigprocmask (SIG_SETMASK, &sc->sc_mask, NULL):
 
@@ -42,6 +42,7 @@
        mov out0 = SIG_SETMASK
        add out1 = r2, in0
        mov out2 = 0
+       mov out3 = 8            // sizeof( sigset_t )
 
        invala
        break __BREAK_SYSCALL
diff -Nru glibc-2.3.2/sysdeps/unix/sysv/linux/ia64/ucontext_i.h 
glibc-2.3.2-work/sysdeps/unix/sysv/linux/ia64/ucontext_i.h
- --- glibc-2.3.2/sysdeps/unix/sysv/linux/ia64/ucontext_i.h     Sat Jul  7 
15:21:35 2001
+++ glibc-2.3.2-work/sysdeps/unix/sysv/linux/ia64/ucontext_i.h  Thu May  1 
13:02:51 2003
@@ -35,7 +35,7 @@
 #define SC_BR  0x088
 #define SC_GR  0x0c8
 #define SC_FR  0x1d0
- -#define SC_MASK      0x9d0
+#define SC_MASK        0xa50
 
 
 #define rTMP   r16
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