This is a note to let you know that I've just added the patch titled
riscv/atomic: Fix sign extension for RV64I
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
riscv-atomic-fix-sign-extension-for-rv64i.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c7781a8b2a839a739c84632addf90f10e3cd6083
Author: Nathan Huckleberry <nhuck@xxxxxxxxxx>
Date: Thu Jun 11 18:32:35 2020 +0000
riscv/atomic: Fix sign extension for RV64I
[ Upstream commit 6c58f25e6938c073198af8b1e1832f83f8f0df33 ]
The argument passed to cmpxchg is not guaranteed to be sign
extended, but lr.w sign extends on RV64I. This makes cmpxchg
fail on clang built kernels when __old is negative.
To fix this, we just cast __old to long which sign extends on
RV64I. With this fix, clang built RISC-V kernels now boot.
Link: https://github.com/ClangBuiltLinux/linux/issues/867
Signed-off-by: Nathan Huckleberry <nhuck@xxxxxxxxxx>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpxchg.h
index d969bab4a26b5..262e5bbb27760 100644
--- a/arch/riscv/include/asm/cmpxchg.h
+++ b/arch/riscv/include/asm/cmpxchg.h
@@ -179,7 +179,7 @@
" bnez %1, 0b\n" \
"1:\n" \
: "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \
- : "rJ" (__old), "rJ" (__new) \
+ : "rJ" ((long)__old), "rJ" (__new) \
: "memory"); \
break; \
case 8: \
@@ -224,7 +224,7 @@
RISCV_ACQUIRE_BARRIER \
"1:\n" \
: "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \
- : "rJ" (__old), "rJ" (__new) \
+ : "rJ" ((long)__old), "rJ" (__new) \
: "memory"); \
break; \
case 8: \
@@ -270,7 +270,7 @@
" bnez %1, 0b\n" \
"1:\n" \
: "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \
- : "rJ" (__old), "rJ" (__new) \
+ : "rJ" ((long)__old), "rJ" (__new) \
: "memory"); \
break; \
case 8: \
@@ -316,7 +316,7 @@
" fence rw, rw\n" \
"1:\n" \
: "=&r" (__ret), "=&r" (__rc), "+A" (*__ptr) \
- : "rJ" (__old), "rJ" (__new) \
+ : "rJ" ((long)__old), "rJ" (__new) \
: "memory"); \
break; \
case 8: \
