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Mark Rutland 781c262033 atomics: Fix atomic64_{read_acquire,set_release} fallbacks 
[ Upstream commit dc1b4df09a ]

Arnd reports that on 32-bit architectures, the fallbacks for
atomic64_read_acquire() and atomic64_set_release() are broken as they
use smp_load_acquire() and smp_store_release() respectively, which do
not work on types larger than the native word size.

Since those contain compiletime_assert_atomic_type(), any attempt to use
those fallbacks will result in a build-time error. e.g. with the
following added to arch/arm/kernel/setup.c:

| void test_atomic64(atomic64_t *v)
| {
|        atomic64_set_release(v, 5);
|        atomic64_read_acquire(v);
| }

The compiler will complain as follows:

| In file included from <command-line>:
| In function 'arch_atomic64_set_release',
|     inlined from 'test_atomic64' at ./include/linux/atomic/atomic-instrumented.h:669:2:
| ././include/linux/compiler_types.h:346:38: error: call to '__compiletime_assert_9' declared with attribute error: Need native word sized stores/loads for atomicity.
|   346 |  _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
|       |                                      ^
| ././include/linux/compiler_types.h:327:4: note: in definition of macro '__compiletime_assert'
|   327 |    prefix ## suffix();    \
|       |    ^~~~~~
| ././include/linux/compiler_types.h:346:2: note: in expansion of macro '_compiletime_assert'
|   346 |  _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
|       |  ^~~~~~~~~~~~~~~~~~~
| ././include/linux/compiler_types.h:349:2: note: in expansion of macro 'compiletime_assert'
|   349 |  compiletime_assert(__native_word(t),    \
|       |  ^~~~~~~~~~~~~~~~~~
| ./include/asm-generic/barrier.h:133:2: note: in expansion of macro 'compiletime_assert_atomic_type'
|   133 |  compiletime_assert_atomic_type(*p);    \
|       |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| ./include/asm-generic/barrier.h:164:55: note: in expansion of macro '__smp_store_release'
|   164 | #define smp_store_release(p, v) do { kcsan_release(); __smp_store_release(p, v); } while (0)
|       |                                                       ^~~~~~~~~~~~~~~~~~~
| ./include/linux/atomic/atomic-arch-fallback.h:1270:2: note: in expansion of macro 'smp_store_release'
|  1270 |  smp_store_release(&(v)->counter, i);
|       |  ^~~~~~~~~~~~~~~~~
| make[2]: *** [scripts/Makefile.build:288: arch/arm/kernel/setup.o] Error 1
| make[1]: *** [scripts/Makefile.build:550: arch/arm/kernel] Error 2
| make: *** [Makefile:1831: arch/arm] Error 2

Fix this by only using smp_load_acquire() and smp_store_release() for
native atomic types, and otherwise falling back to the regular barriers
necessary for acquire/release semantics, as we do in the more generic
acquire and release fallbacks.

Since the fallback templates are used to generate the atomic64_*() and
atomic_*() operations, the __native_word() check is added to both. For
the atomic_*() operations, which are always 32-bit, the __native_word()
check is redundant but not harmful, as it is always true.

For the example above this works as expected on 32-bit, e.g. for arm
multi_v7_defconfig:

| <test_atomic64>:
|         push    {r4, r5}
|         dmb     ish
|         pldw    [r0]
|         mov     r2, #5
|         mov     r3, #0
|         ldrexd  r4, [r0]
|         strexd  r4, r2, [r0]
|         teq     r4, #0
|         bne     484 <test_atomic64+0x14>
|         ldrexd  r2, [r0]
|         dmb     ish
|         pop     {r4, r5}
|         bx      lr

... and also on 64-bit, e.g. for arm64 defconfig:

| <test_atomic64>:
|         bti     c
|         paciasp
|         mov     x1, #0x5
|         stlr    x1, [x0]
|         ldar    x0, [x0]
|         autiasp
|         ret

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20220207101943.439825-1-mark.rutland@arm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
 		2022-04-08 13:58:39 +02:00
Documentation cxl/core/port: Rename bus.c to port.c 2022-04-08 13:58:07 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
arch parisc: Fix handling off probe non-access faults 2022-04-08 13:58:38 +02:00
block Revert "Revert "block, bfq: honor already-setup queue merges"" 2022-04-08 13:58:38 +02:00
certs certs: Fix build error when CONFIG_MODULE_SIG_KEY is empty 2022-01-23 00:08:44 +09:00
crypto crypto: xts - Add softdep on ecb 2022-04-08 13:58:36 +02:00
drivers spi: fsi: Implement a timeout for polling status 2022-04-08 13:58:39 +02:00
fs fs/binfmt_elf: Fix AT_PHDR for unusual ELF files 2022-04-08 13:58:37 +02:00
include atomics: Fix atomic64_{read_acquire,set_release} fallbacks 2022-04-08 13:58:39 +02:00
init lib/stackdepot: allow optional init and stack_table allocation by kvmalloc() 2022-01-22 08:33:37 +02:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-04 09:25:05 -08:00
kernel rcu: Mark writes to the rcu_segcblist structure's ->flags field 2022-04-08 13:58:36 +02:00
lib lib/raid6/test/Makefile: Use $(pound) instead of \# for Make 4.3 2022-04-08 13:58:38 +02:00
mm mm/kmemleak: reset tag when compare object pointer 2022-04-08 13:57:23 +02:00
net net/sched: act_ct: fix ref leak when switching zones 2022-04-08 13:58:35 +02:00
samples samples/bpf, xdpsock: Fix race when running for fix duration of time 2022-04-08 13:58:18 +02:00
scripts atomics: Fix atomic64_{read_acquire,set_release} fallbacks 2022-04-08 13:58:39 +02:00
security Fix incorrect type in assignment of ipv6 port for audit 2022-04-08 13:58:37 +02:00
sound ASoC: amd: Fix reference to PCM buffer address 2022-04-08 13:57:54 +02:00
tools selftests: tls: skip cmsg_to_pipe tests with TLS=n 2022-04-08 13:58:34 +02:00
usr kbuild: remove include/linux/cyclades.h from header file check 2022-01-27 08:51:08 +01:00
virt KVM: Fix lockdep false negative during host resume 2022-02-17 09:52:50 -05:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
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MAINTAINERS net: dsa: realtek-smi: move to subdirectory 2022-04-08 13:58:12 +02:00
Makefile Linux 5.17.1 2022-03-28 10:03:22 +02:00
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