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From: Daniel Cederman <cederman@gaisler.com>
To: libc-alpha@sourceware.org
Cc: daniel@gaisler.com, andreas@gaisler.com
Subject: [PATCH] sparc: Remove unwind information from signal return stub functions
Date: Fri, 12 Jan 2024 10:26:28 +0100	[thread overview]
Message-ID: <20240112092628.2464455-6-cederman@gaisler.com> (raw)
In-Reply-To: <20240112092628.2464455-1-cederman@gaisler.com>

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.

This patch fixes the issues I have seen, but I am not sure if this is
the right solution, so any feedback is welcome!

Signed-off-by: Daniel Cederman <cederman@gaisler.com>
---
 sysdeps/sparc/sysdep.h                                |  9 +++++++++
 .../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 c00fe79fec..44a6952bff 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 832223f8ce..21d36c50df 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)
-- 
2.40.1


  parent reply	other threads:[~2024-01-12  9:26 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-12  9:26 [PATCH] sparc: Do not test preservation of NaN payloads for LEON Daniel Cederman
2024-01-12  9:26 ` [PATCH] sparc: Prevent stfsr from directly following floating-point instruction Daniel Cederman
2024-01-12 14:38   ` Adhemerval Zanella Netto
2024-01-15  9:37     ` Daniel Cederman
2024-01-12  9:26 ` [PATCH] sparc: Force calculation that raises exception Daniel Cederman
2024-01-12 16:45   ` Adhemerval Zanella Netto
2024-01-15  9:41     ` Daniel Cederman
2024-01-15 11:47       ` Adhemerval Zanella Netto
2024-01-12  9:26 ` [PATCH] sparc: Treat the version field in the FPU control word as reserved Daniel Cederman
2024-01-12 17:42   ` Adhemerval Zanella Netto
2024-02-15  9:31     ` Daniel Cederman
2024-02-19 14:55       ` Adhemerval Zanella Netto
2024-01-12  9:26 ` [PATCH] sparc: Fix llrint and llround missing exceptions on SPARC32 Daniel Cederman
2024-01-12 18:05   ` Adhemerval Zanella Netto
2024-01-15 14:38     ` Daniel Cederman
2024-01-15 17:52       ` Adhemerval Zanella Netto
2024-01-12  9:26 ` Daniel Cederman [this message]
2024-01-15 13:41   ` [PATCH] sparc: Remove unwind information from signal return stub functions Adhemerval Zanella Netto
2024-01-15 14:22     ` Daniel Cederman
2024-01-15 16:57       ` Adhemerval Zanella Netto
2024-01-16 15:37 ` [PATCH] sparc: Do not test preservation of NaN payloads for LEON Adhemerval Zanella Netto

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