From: Matheus Castanho <msc@linux.ibm.com>
To: libc-alpha@sourceware.org
Cc: npiggin@gmail.com, tuliom@linux.ibm.com
Subject: [PATCH] powerpc: Add missing registers to clobbers list for syscalls [BZ #27623]
Date: Mon, 22 Mar 2021 11:20:35 -0300 [thread overview]
Message-ID: <20210322142035.183915-1-msc@linux.ibm.com> (raw)
Some registers that can be clobbered by the kernel during a syscall are not
listed on the clobbers list in sysdeps/unix/sysv/linux/powerpc/sysdep.h.
For syscalls using sc:
- XER is zeroed by the kernel on exit
For syscalls using scv:
- XER is zeroed by the kernel on exit
- Different from the sc case, most CR fields can be clobbered (according to
the ELF ABI and the Linux kernel's syscall ABI for powerpc
(linux/Documentation/powerpc/syscall64-abi.rst)
These are likely not causing issues today, but they should be added to the
clobbers list just in case things change on the kernel side in the future.
Reported-by: Nicholas Piggin <npiggin@gmail.com>
---
sysdeps/unix/sysv/linux/powerpc/sysdep.h | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/powerpc/sysdep.h b/sysdeps/unix/sysv/linux/powerpc/sysdep.h
index 6b99464e61..d15e80d610 100644
--- a/sysdeps/unix/sysv/linux/powerpc/sysdep.h
+++ b/sysdeps/unix/sysv/linux/powerpc/sysdep.h
@@ -86,7 +86,8 @@
"=&r" (r6), "=&r" (r7), "=&r" (r8) \
: ASM_INPUT_##nr \
: "r9", "r10", "r11", "r12", \
- "lr", "ctr", "memory"); \
+ "cr0", "cr1", "cr5", "cr6", "cr7", \
+ "xer", "lr", "ctr", "memory"); \
r3; \
})
@@ -101,7 +102,7 @@
"=&r" (r6), "=&r" (r7), "=&r" (r8) \
: ASM_INPUT_##nr \
: "r9", "r10", "r11", "r12", \
- "cr0", "ctr", "memory"); \
+ "xer", "cr0", "ctr", "memory"); \
r0 & (1 << 28) ? -r3 : r3; \
})
--
2.30.2
next reply other threads:[~2021-03-22 14:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-22 14:20 Matheus Castanho [this message]
2021-03-22 14:42 ` Andreas Schwab
2021-03-29 13:27 ` Matheus Castanho
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