riscv/futex: sign extend compare value in atomic cmpxchg

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commit 599c44cd21 upstream.

Make sure the compare value in the lr/sc loop is sign extended to match
what lr.w does.  Fortunately, due to the compiler keeping the register
contents sign extended anyway the lack of the explicit extension didn't
result in wrong code so far, but this cannot be relied upon.

Fixes: b90edb3301 ("RISC-V: Add futex support.")
Signed-off-by: Andreas Schwab <schwab@suse.de>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/mvmfrkv2vhz.fsf@suse.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Andreas Schwab 2025-02-03 11:06:00 +01:00 • committed by Greg Kroah-Hartman

parent 84586322e0

commit ee3ab05cf7

1 changed files with 1 additions and 1 deletions

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arch/riscv/include/asm/futex.h

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