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riscv/atomic: Fix sign extension for RV64I

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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@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Nathan Huckleberry 2020-06-11 18:32:35 +00:00 committed by Palmer Dabbelt
parent cd16ed33c3
commit 6c58f25e69
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GPG Key ID: 2E1319F35FBB1889
1 changed files with 4 additions and 4 deletions
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8
arch/riscv/include/asm/cmpxchg.h
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@ -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: \