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selftests/futex: Fix futex_wait() for 32bit ARM 

On 32bit ARM systems gcc-12 will use 32bit timestamps while gcc-13 and later
will use 64bit timestamps.  The problem is that SYS_futex will continue
pointing at the 32bit system call.  This makes the futex_wait test fail like
this:

  waiter failed errno 110
  not ok 1 futex_wake private returned: 0 Success
  waiter failed errno 110
  not ok 2 futex_wake shared (page anon) returned: 0 Success
  waiter failed errno 110
  not ok 3 futex_wake shared (file backed) returned: 0 Success

Instead of compiling differently depending on the gcc version, use the
-D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 options to ensure that 64bit timestamps
are used.  Then use ifdefs to make SYS_futex point to the 64bit system call.

Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Link: https://lore.kernel.org/20250827130011.677600-6-bigeasy@linutronix.de
pull/1354/merge
Dan Carpenter 2025-08-27 15:00:11 +02:00 committed by Borislav Petkov (AMD)
parent 5fdb877b49
commit 237bfb76c9
2 changed files with 12 additions and 1 deletions
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2
tools/testing/selftests/futex/functional/Makefile
View File

@ -1,6 +1,6 @@
# SPDX-License-Identifier: GPL-2.0
INCLUDES := -I../include -I../../ $(KHDR_INCLUDES)
CFLAGS := $(CFLAGS) -g -O2 -Wall -pthread $(INCLUDES) $(KHDR_INCLUDES)
CFLAGS := $(CFLAGS) -g -O2 -Wall -pthread -D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64 $(INCLUDES) $(KHDR_INCLUDES)
LDLIBS := -lpthread -lrt -lnuma
LOCAL_HDRS := \

11
tools/testing/selftests/futex/include/futextest.h
View File

@ -58,6 +58,17 @@ typedef volatile u_int32_t futex_t;
#define SYS_futex SYS_futex_time64
#endif
/*
* On 32bit systems if we use "-D_FILE_OFFSET_BITS=64 -D_TIME_BITS=64" or if
* we are using a newer compiler then the size of the timestamps will be 64bit,
* however, the SYS_futex will still point to the 32bit futex system call.
*/
#if __SIZEOF_POINTER__ == 4 && defined(SYS_futex_time64) && \
defined(_TIME_BITS) && _TIME_BITS == 64
# undef SYS_futex
# define SYS_futex SYS_futex_time64
#endif
/**
* futex() - SYS_futex syscall wrapper
* @uaddr: address of first futex