@@ -11,8 +11,12 @@ ifeq ($(subdir),sysvipc)
sysdep_routines += getshmlba
endif
+ifeq ($(subdir),signal)
+sysdep_routines += sigreturn_stub
+endif
+
ifeq ($(subdir),nptl)
# pull in __syscall_error routine
-libpthread-routines += sysdep
-libpthread-shared-only-routines += sysdep
+libpthread-routines += sysdep sigreturn_stub
+libpthread-shared-only-routines += sysdep sigreturn_stub
endif
@@ -24,8 +24,8 @@
#include <kernel_sigaction.h>
#include <sysdep.h>
-static void __rt_sigreturn_stub (void);
-static void __sigreturn_stub (void);
+void __rt_sigreturn_stub (void);
+void __sigreturn_stub (void);
#define STUB(act, sigsetsize) \
(act) ? ((unsigned long)((act->sa_flags & SA_SIGINFO) \
@@ -35,25 +35,3 @@ static void __sigreturn_stub (void);
(sigsetsize)
#include <sysdeps/unix/sysv/linux/sigaction.c>
-
-static
-inhibit_stack_protector
-void
-__rt_sigreturn_stub (void)
-{
- __asm__ ("mov %0, %%g1\n\t"
- "ta 0x10\n\t"
- : /* no outputs */
- : "i" (__NR_rt_sigreturn));
-}
-
-static
-inhibit_stack_protector
-void
-__sigreturn_stub (void)
-{
- __asm__ ("mov %0, %%g1\n\t"
- "ta 0x10\n\t"
- : /* no outputs */
- : "i" (__NR_sigreturn));
-}
new file mode 100644
@@ -0,0 +1,29 @@
+/* Sigreturn stub function used on sa_restore field.
+ Copyright (C) 2020 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+ENTRY (__rt_sigreturn_stub)
+ mov __NR_rt_sigreturn, %g1
+ ta 0x10
+END (__rt_sigreturn_stub)
+
+ENTRY (__sigreturn_stub)
+ mov __NR_sigreturn, %g1
+ ta 0x10
+END (__sigreturn_stub)
@@ -22,21 +22,11 @@
#include <syscall.h>
#include <sysdep.h>
-static void __rt_sigreturn_stub (void);
+/* Defined on sigreturn_stub.S. */
+void __rt_sigreturn_stub (void);
#define STUB(act, sigsetsize) \
(((unsigned long) &__rt_sigreturn_stub) - 8), \
(sigsetsize)
#include <sysdeps/unix/sysv/linux/sigaction.c>
-
-static
-inhibit_stack_protector
-void
-__rt_sigreturn_stub (void)
-{
- __asm__ ("mov %0, %%g1\n\t"
- "ta 0x6d\n\t"
- : /* no outputs */
- : "i" (__NR_rt_sigreturn));
-}
new file mode 100644
@@ -0,0 +1,24 @@
+/* Sigreturn stub function used on sa_restore field.
+ Copyright (C) 2020 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+ENTRY (__rt_sigreturn_stub)
+ mov __NR_rt_sigreturn, %g1
+ ta 0x6d
+END (__rt_sigreturn_stub)
It seems that some gcc versions might generates a stack frame for the sigreturn stub requires on sparc signal handling. For instance: $ cat test.c #define _GNU_SOURCE #include <sys/syscall.h> __attribute__ ((__optimize__ ("-fno-stack-protector"))) void __sigreturn_stub (void) { __asm__ ("mov %0, %%g1\n\t" "ta 0x10\n\t" : /* no outputs */ : "i" (SYS_rt_sigreturn)); } $ gcc -v [...] gcc version 9.2.1 20200224 (Debian 9.2.1-30) $ gcc -O2 -m64 test.c -S -o - [...] __sigreturn_stub: save %sp, -176, %sp #APP ! 9 "t.c" 1 mov 101, %g1 ta 0x10 ! 0 "" 2 #NO_APP .size __sigreturn_stub, .-__sigreturn_stub As indicated by kernel developers [1], the sigreturn stub can not change the register window or the stack pointer since the kernel has setup the restore frame at a precise location relative to the stack pointer when the stub is invoked. I tried to play with some compiler flags and even with _Noreturn and __builtin_unreachable after the asm does not help (and Sparc does not support naked functions). To avoid similar issues, as the stack-protector support also have stumbled, this patch moves the implementation of the sigreturn stubs to assembly. Checked on sparcv9-linux-gnu and sparc64-linux-gnu with gcc 9.2.1 and gcc 7.5.0. [1] https://lkml.org/lkml/2016/5/27/465 --- sysdeps/unix/sysv/linux/sparc/Makefile | 8 +++-- .../unix/sysv/linux/sparc/sparc32/sigaction.c | 26 ++--------------- .../sysv/linux/sparc/sparc32/sigreturn_stub.S | 29 +++++++++++++++++++ .../unix/sysv/linux/sparc/sparc64/sigaction.c | 14 ++------- .../sysv/linux/sparc/sparc64/sigreturn_stub.S | 24 +++++++++++++++ 5 files changed, 63 insertions(+), 38 deletions(-) create mode 100644 sysdeps/unix/sysv/linux/sparc/sparc32/sigreturn_stub.S create mode 100644 sysdeps/unix/sysv/linux/sparc/sparc64/sigreturn_stub.S -- 2.17.1