[PATCH v3 1/7] Fix __libc_signal_block_all on sparc64

[Adhemerval Zanella <adhemerval dot zanella at linaro dot org>]

Changes from previous version:

  - Remove unrelated changes.

--

The a2e8aa0d9e shows two regressions on sparc64-linux-gnu:

  nptl/tst-cancel-self-canceltype
  nptl/tst-cancel5

This is not from the patch itself, but rather from an invalid
__NR_rt_sigprocmask issued by the loader:

  rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
  rt_sigprocmask(0xffd07c60 /* SIG_??? */, ~[], 0x7feffd07d08, 8) = -1 EINVAL (Invalid argument)

Tracking the culprit it really seems a wrong code generation in the
INTERNAL_SYSCALL due the automatic sigset_t used on
__libc_signal_block_all:

  return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &SIGALL_SET,
                          set, _NSIG / 8);

Where SIGALL_SET is defined as:

  ((__sigset_t) { .__val = {[0 ...  _SIGSET_NWORDS-1 ] =  -1 } })

Building the expanded __libc_signal_block_all on sparc64 with recent
compiler (gcc 8.3.1 and 9.1.1):

  #include <signal>

  int
  _libc_signal_block_all (sigset_t *set)
  {
    INTERNAL_SYSCALL_DECL (err);
    return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &SIGALL_SET,
			     set, _NSIG / 8);
  }

It seems that the first argument (SIG_BLOCK) is not correctly set on
'o0' register:

  __libc_signal_block_all:
	save    %sp, -304, %sp
	add     %fp, 1919, %o0
	mov     128, %o2
	sethi   %hi(.LC0), %o1
	call    memcpy, 0
	 or     %o1, %lo(.LC0), %o1
	add     %fp, 1919, %o1
	mov     %i0, %o2
	mov     8, %o3
	mov     103, %g1
	ta      0x6d;
	bcc,pt  %xcc, 1f
	mov     0, %g1
	sub     %g0, %o0, %o0
	mov     1, %g1
     1:	sra     %o0, 0, %i0
	return  %i7+8
	 nop

Where is I define SIGALL_SET outside INTERNAL_SYSCALL macro, gcc
correctly sets the expected kernel argument in correct register:

        sethi   %hi(.LC0), %o1
        call    memcpy, 0
         or     %o1, %lo(.LC0), %o1
   ->   mov     1, %o0
	add     %fp, 1919, %o1

This patch fixes it by moving both sigset_t that represent all signals
sets and the application set to constant data objects.

Checked on x86_64-linux-gnu, i686-linux-gnu, and sparc64-linux-gnu.
---
 sysdeps/unix/sysv/linux/internal-signals.h | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/internal-signals.h b/sysdeps/unix/sysv/linux/internal-signals.h
index 01d8bf0a4c..a496c7174c 100644
--- a/sysdeps/unix/sysv/linux/internal-signals.h
+++ b/sysdeps/unix/sysv/linux/internal-signals.h
@@ -22,6 +22,7 @@
 #include <signal.h>
 #include <sigsetops.h>
 #include <stdbool.h>
+#include <limits.h>
 #include <sysdep.h>
 
 /* The signal used for asynchronous cancelation.  */
@@ -53,15 +54,16 @@ __clear_internal_signals (sigset_t *set)
   __sigdelset (set, SIGSETXID);
 }
 
-#define SIGALL_SET \
-  ((__sigset_t) { .__val = {[0 ...  _SIGSET_NWORDS-1 ] =  -1 } })
+static const sigset_t sigall_set = {
+   .__val = {[0 ...  _SIGSET_NWORDS-1 ] =  -1 }
+};
 
 /* Block all signals, including internal glibc ones.  */
 static inline int
 __libc_signal_block_all (sigset_t *set)
 {
   INTERNAL_SYSCALL_DECL (err);
-  return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &SIGALL_SET,
+  return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &sigall_set,
 			   set, _NSIG / 8);
 }
 
@@ -69,11 +71,11 @@ __libc_signal_block_all (sigset_t *set)
 static inline int
 __libc_signal_block_app (sigset_t *set)
 {
-  sigset_t allset = SIGALL_SET;
+  sigset_t allset = sigall_set;
   __clear_internal_signals (&allset);
   INTERNAL_SYSCALL_DECL (err);
-  return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &allset, set,
-			   _NSIG / 8);
+  return INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_BLOCK, &allset,
+			   set, _NSIG / 8);
 }
 
 /* Restore current process signal mask.  */
-- 
2.17.1