From: Nathan Huckleberry <nhuck@google.com>
To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
clang-built-linux@googlegroups.com,
Nathan Huckleberry <nhuck@google.com>
Subject: [PATCH] riscv/atomic: Fix sign extension for RV64I
Date: Thu, 11 Jun 2020 18:32:35 +0000 [thread overview]
Message-ID: <20200611183235.37508-1-nhuck@google.com> (raw)
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
Cc: clang-built-linux@googlegroups.com
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
---
arch/riscv/include/asm/cmpxchg.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpxchg.h
index d969bab4a26b..262e5bbb2776 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: \
--
2.27.0.278.ge193c7cf3a9-goog
next reply other threads:[~2020-06-11 18:34 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-11 18:32 Nathan Huckleberry [this message]
2020-06-11 18:49 ` Nick Desaulniers
2020-06-18 21:43 ` Palmer Dabbelt
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