kernel.git/arch/s390/include/asm/bitops.h, branch linux-6.15.y

s390/bitops: Disable arch_test_bit() optimization for PROFILE_ALL_BRANCHES

2025-02-11T18:35:08Z

With PROFILE_ALL_BRANCHES enabled gcc sometimes fails to handle __builtin_constant_p() correctly: In function 'arch_test_bit', inlined from 'node_state' at include/linux/nodemask.h:423:9, inlined from 'warn_if_node_offline' at include/linux/gfp.h:252:2, inlined from '__alloc_pages_node_noprof' at include/linux/gfp.h:267:2, inlined from 'alloc_pages_node_noprof' at include/linux/gfp.h:296:9, inlined from 'vm_area_alloc_pages.constprop' at mm/vmalloc.c:3591:11: >> arch/s390/include/asm/bitops.h:60:17: warning: 'asm' operand 2 probably does not match constraints 60 | asm volatile( | ^~~ >> arch/s390/include/asm/bitops.h:60:17: error: impossible constraint in 'asm' Therefore disable the optimization for this case. This is similar to commit 63678eecec57 ("s390/preempt: disable __preempt_count_add() optimization for PROFILE_ALL_BRANCHES") Fixes: b2bc1b1a77c0 ("s390/bitops: Provide optimized arch_test_bit()") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202502091912.xL2xTCGw-lkp@intel.com/ Acked-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/bitops: Use correct constraint for arch_test_bit() inline assembly

2025-01-26T16:24:08Z

Use the "Q" instead of "R" constraint to correctly reflect the instruction format of the tm instruction: the first operand is a memory reference without index register and short displacement. The "R" constraint indicates a memory reference with index register instead. This may lead to compile errors like: arch/s390/include/asm/bitops.h: Assembler messages: arch/s390/include/asm/bitops.h:60: Error: operand 1: syntax error; missing ')' after base register arch/s390/include/asm/bitops.h:60: Error: operand 2: syntax error; ')' not allowed here arch/s390/include/asm/bitops.h:60: Error: junk at end of line: `,4' Reported-by: Nathan Chancellor Closes: https://lore.kernel.org/r/20250122-s390-fix-std-for-gcc-15-v1-1-8b00cadee083@kernel.org Fixes: b2bc1b1a77c0 ("s390/bitops: Provide optimized arch_test_bit()") Acked-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev

s390/bitops: Provide optimized arch_test_bit()

2025-01-13T08:50:19Z

Provide an optimized arch_test_bit() implementation which makes use of flag output constraint. This generates slightly better code: bloat-o-meter: add/remove: 51/19 grow/shrink: 450/2444 up/down: 25198/-49136 (-23938) Acked-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev

s390/bitops: Switch to generic bitops

2025-01-13T08:50:18Z

The generic bitops implementation is nearly identical to the s390 implementation therefore switch to the generic variant. This results in a small kernel image size decrease. This is because for the generic variant the nr parameter for most bitops functions is of type unsigned int while the s390 variant uses unsigned long. bloat-o-meter: add/remove: 670/670 grow/shrink: 167/209 up/down: 21440/-21792 (-352) Acked-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev

s390: Provide optimized __arch_hweight*() implementations

2024-06-24T09:12:39Z

Make use of the popcnt instruction to provide optimized __arch_hweight*() implementations. The generated code is shorter and avoids rather expensive functions calls. Acked-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev

s390: implement arch_xor_unlock_is_negative_byte

2023-10-18T21:34:17Z

Inspired by the s390 arch_test_and_clear_bit(), this will surely be more efficient than the generic one defined in filemap.c. Link: https://lkml.kernel.org/r/20231004165317.1061855-14-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Cc: Albert Ou Cc: Alexander Gordeev Cc: Andreas Dilger Cc: Christian Borntraeger Cc: Christophe Leroy Cc: Geert Uytterhoeven Cc: Heiko Carstens Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Richard Henderson Cc: Sven Schnelle Cc: "Theodore Ts'o" Cc: Thomas Bogendoerfer Cc: Vasily Gorbik Signed-off-by: Andrew Morton

provide arch_test_bit_acquire for architectures that define test_bit

2022-08-27T16:49:54Z

Some architectures define their own arch_test_bit and they also need arch_test_bit_acquire, otherwise they won't compile. We also clean up the code by using the generic test_bit if that is equivalent to the arch-specific version. Signed-off-by: Mikulas Patocka Cc: stable@vger.kernel.org Fixes: 8238b4579866 ("wait_on_bit: add an acquire memory barrier") Signed-off-by: Linus Torvalds

bitops: unify non-atomic bitops prototypes across architectures

2022-07-01T02:52:41Z

Currently, there is a mess with the prototypes of the non-atomic bitops across the different architectures: ret bool, int, unsigned long nr int, long, unsigned int, unsigned long addr volatile unsigned long *, volatile void * Thankfully, it doesn't provoke any bugs, but can sometimes make the compiler angry when it's not handy at all. Adjust all the prototypes to the following standard: ret bool retval can be only 0 or 1 nr unsigned long native; signed makes no sense addr volatile unsigned long * bitmaps are arrays of ulongs Next, some architectures don't define 'arch_' versions as they don't support instrumentation, others do. To make sure there is always the same set of callables present and to ease any potential future changes, make them all follow the rule: * architecture-specific files define only 'arch_' versions; * non-prefixed versions can be defined only in asm-generic files; and place the non-prefixed definitions into a new file in asm-generic to be included by non-instrumented architectures. Finally, add some static assertions in order to prevent people from making a mess in this room again. I also used the %__always_inline attribute consistently, so that they always get resolved to the actual operations. Suggested-by: Andy Shevchenko Signed-off-by: Alexander Lobakin Acked-by: Mark Rutland Reviewed-by: Yury Norov Reviewed-by: Andy Shevchenko Signed-off-by: Yury Norov

s390: raise minimum supported machine generation to z10

2022-03-10T14:58:17Z

Machine generations up to z9 (released in May 2006) have been officially out of service for several years now (z9 end of service - January 31, 2019). No distributions build kernels supporting those old machine generations anymore, except Debian, which seems to pick the oldest supported generation. The team supporting Debian on s390 has been notified about the change. Raising minimum supported machine generation to z10 helps to reduce maintenance cost and effectively remove code, which is not getting enough testing coverage due to lack of older hardware and distributions support. Besides that this unblocks some optimization opportunities and allows to use wider instruction set in asm files for future features implementation. Due to this change spectre mitigation and usercopy implementations could be drastically simplified and many newer instructions could be converted from ".insn" encoding to instruction names. Acked-by: Ilya Leoshkevich Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

include: move find.h from asm_generic to linux

2022-01-15T16:47:31Z

find_bit API and bitmap API are closely related, but inclusion paths are different - include/asm-generic and include/linux, correspondingly. In the past it made a lot of troubles due to circular dependencies and/or undefined symbols. Fix this by moving find.h under include/linux. Signed-off-by: Yury Norov Tested-by: Wolfram Sang Acked-by: Geert Uytterhoeven