[glibc/release/2.36/master] sparc: Remove unwind information from signal return stubs [BZ #31244]

[glibc/release/2.36/master] sparc: Remove unwind information from signal return stubs [BZ #31244]

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=2853e541c58af1f5d868c4161ea9562e7876a989

commit 2853e541c58af1f5d868c4161ea9562e7876a989
Author: Daniel Cederman <cederman@gaisler.com>
Date:   Tue Jan 16 09:31:41 2024 +0100

    sparc: Remove unwind information from signal return stubs [BZ #31244]
    
    The functions were previously written in C, but were not compiled
    with unwind information. The ENTRY/END macros includes .cfi_startproc
    and .cfi_endproc which adds unwind information. This caused the
    tests cleanup-8 and cleanup-10 in the GCC testsuite to fail.
    This patch adds a version of the ENTRY/END macros without the
    CFI instructions that can be used instead.
    
    sigaction registers a restorer address that is located two instructions
    before the stub function. This patch adds a two instruction padding to
    avoid that the unwinder accesses the unwind information from the function
    that the linker has placed right before it in memory. This fixes an issue
    with pthread_cancel that caused tst-mutex8-static (and other tests) to fail.
    
    Signed-off-by: Daniel Cederman <cederman@gaisler.com>
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
    (cherry picked from commit 7bd06985c0a143cdcba2762bfe020e53514a53de)

Diff:
---
 sysdeps/sparc/sysdep.h                                 |  9 +++++++++
 sysdeps/unix/sysv/linux/sparc/sparc32/sigreturn_stub.S | 11 +++++++----
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/sysdeps/sparc/sysdep.h b/sysdeps/sparc/sysdep.h
index 95068071cc..baab6817a6 100644
--- a/sysdeps/sparc/sysdep.h
+++ b/sysdeps/sparc/sysdep.h
@@ -76,6 +76,15 @@ C_LABEL(name)				\
 	cfi_endproc;			\
 	.size name, . - name
 
+#define ENTRY_NOCFI(name)			\
+	.align	4;			\
+	.global	C_SYMBOL_NAME(name);	\
+	.type	name, @function;	\
+C_LABEL(name)
+
+#define END_NOCFI(name)			\
+	.size name, . - name
+
 #undef LOC
 #define LOC(name)  .L##name
 
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/sigreturn_stub.S b/sysdeps/unix/sysv/linux/sparc/sparc32/sigreturn_stub.S
index 2829e881eb..a1492ea59e 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/sigreturn_stub.S
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/sigreturn_stub.S
@@ -23,12 +23,15 @@
 
    [1] https://lkml.org/lkml/2016/5/27/465  */
 
-ENTRY (__rt_sigreturn_stub)
+	nop
+	nop
+
+ENTRY_NOCFI (__rt_sigreturn_stub)
 	mov	__NR_rt_sigreturn, %g1
 	ta	0x10
-END (__rt_sigreturn_stub)
+END_NOCFI (__rt_sigreturn_stub)
 
-ENTRY (__sigreturn_stub)
+ENTRY_NOCFI (__sigreturn_stub)
 	mov	__NR_sigreturn, %g1
 	ta	0x10
-END (__sigreturn_stub)
+END_NOCFI (__sigreturn_stub)