kernel/linux.git/arch/s390/include/asm/cpu_mf.h, branch linux-7.0.y

s390: Use inline qualifier for all EX_TABLE and ALTERNATIVE inline assemblies

2025-03-18T16:13:51+00:00

Use asm_inline for all inline assemblies which make use of the EX_TABLE or ALTERNATIVE macros. These macros expand to many lines and the compiler assumes the number of lines within an inline assembly is the same as the number of instructions within an inline assembly. This has an effect on inlining and loop unrolling decisions. In order to avoid incorrect assumptions use asm_inline, which tells the compiler that an inline assembly has the smallest possible size. In order to avoid confusion when asm_inline should be used or not, since a couple of inline assemblies are quite large: the rule is to always use asm_inline whenever the EX_TABLE or ALTERNATIVE macro is used. In specific cases there may be reasons to not follow this guideline, but that should be documented with the corresponding code. Using the inline qualifier everywhere has only a small effect on the kernel image size: add/remove: 0/10 grow/shrink: 19/8 up/down: 1492/-1858 (-366) The only location where this seems to matter is load_unaligned_zeropad() from word-at-a-time.h where the compiler inlines more functions within the dcache code, which is indeed code where performance matters. Suggested-by: Juergen Christ Reviewed-by: Juergen Christ Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/cpu_mf: Convert to use flag output macros

2024-11-13T13:31:32+00:00

Use flag output macros in inline asm to allow for better code generation if the compiler has support for the flag output constraint. Reviewed-by: Juergen Christ Signed-off-by: Heiko Carstens

s390/cpumf: unpoison STCCTM output buffer

2024-07-04T02:30:24+00:00

stcctm() uses the "Q" constraint for dest, therefore KMSAN does not understand that it fills multiple doublewords pointed to by dest, not just one. This results in false positives. Unpoison the whole dest manually with kmsan_unpoison_memory(). Link: https://lkml.kernel.org/r/20240621113706.315500-28-iii@linux.ibm.com Signed-off-by: Ilya Leoshkevich Reported-by: Alexander Gordeev Reviewed-by: Alexander Potapenko Acked-by: Heiko Carstens Cc: Christian Borntraeger Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Vyukov Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Joonsoo Kim Cc: Cc: Marco Elver Cc: Mark Rutland Cc: Masami Hiramatsu (Google) Cc: Pekka Enberg Cc: Roman Gushchin Cc: Steven Rostedt (Google) Cc: Sven Schnelle Cc: Vasily Gorbik Cc: Vlastimil Babka Signed-off-by: Andrew Morton

s390/cpum_sf: Convert to cmpxchg128()

2023-06-05T07:36:40+00:00

Now that there is a cross arch u128 and cmpxchg128(), use those instead of the custom CDSG helper. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Arnd Bergmann Reviewed-by: Mark Rutland Acked-by: Heiko Carstens Tested-by: Mark Rutland Link: https://lore.kernel.org/r/20230531132324.058821078@infradead.org

s390/cpum_sf: move functions from header file to source file

2023-01-22T17:42:34+00:00

Some inline helper functions are defined in a header file but used in only one source file. Move these functions to the source file. No functional change. Signed-off-by: Thomas Richter Acked-by: Heiko Carstens Signed-off-by: Heiko Carstens

s390/cpum_sf: add READ_ONCE() semantics to compare and swap loops

2023-01-11T14:28:34+00:00

The current cmpxchg_double() loops within the perf hw sampling code do not have READ_ONCE() semantics to read the old value from memory. This allows the compiler to generate code which reads the "old" value several times from memory, which again allows for inconsistencies. For example: /* Reset trailer (using compare-double-and-swap) */ do { te_flags = te->flags & ~SDB_TE_BUFFER_FULL_MASK; te_flags |= SDB_TE_ALERT_REQ_MASK; } while (!cmpxchg_double(&te->flags, &te->overflow, te->flags, te->overflow, te_flags, 0ULL)); The compiler could generate code where te->flags used within the cmpxchg_double() call may be refetched from memory and which is not necessarily identical to the previous read version which was used to generate te_flags. Which in turn means that an incorrect update could happen. Fix this by adding READ_ONCE() semantics to all cmpxchg_double() loops. Given that READ_ONCE() cannot generate code on s390 which atomically reads 16 bytes, use a private compare-and-swap-double implementation to achieve that. Also replace cmpxchg_double() with the private implementation to be able to re-use the old value within the loops. As a side effect this converts the whole code to only use bit fields to read and modify bits within the hws trailer header. Reported-by: Alexander Gordeev Acked-by: Alexander Gordeev Acked-by: Hendrik Brueckner Reviewed-by: Thomas Richter Cc: Link: https://lore.kernel.org/linux-s390/Y71QJBhNTIatvxUT@osiris/T/#ma14e2a5f7aa8ed4b94b6f9576799b3ad9c60f333 Signed-off-by: Heiko Carstens

s390: convert ".insn" encoding to instruction names

2022-03-10T14:58:17+00:00

With z10 as minimum supported machine generation many ".insn" encodings could be now converted to instruction names. There are couple of exceptions - stfle is used from the als code built for z900 and cannot be converted - few ".insn" directives encode unsupported instruction formats The generated code is identical before/after this change. Acked-by: Ilya Leoshkevich Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/extable: move EX_TABLE define to asm-extable.h

2022-03-07T23:33:00+00:00

Follow arm64 and riscv and move the EX_TABLE define to asm-extable.h which is a lot less generic than the current linkage.h. Also make sure that all files which contain EX_TABLE usages actually include the new header file. This should make sure that the files always compile and there won't be any random compile breakage due to other header file dependencies. Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/cpumf: Support for CPU Measurement Sampling Facility LS bit

2022-01-17T13:13:08+00:00

Adds support for the CPU Measurement Sampling Facility limit sampling bit in the sampling device driver. Limited samples have no valueable information are not collected. Signed-off-by: Thomas Richter Acked-by: Sumanth Korikkar Signed-off-by: Heiko Carstens

s390/cpum_sf: Replace function name in debug statements

2019-11-30T09:52:46+00:00

Replace hard coded function names in debug statements by the "%s ...", __func__ construct suggested by checkpatch.pl script. Use consistent debug print format of the form variable blank value. Also add leading 0x for all hex values. Print allocated page addresses consistantly as hex numbers with leading 0x. Signed-off-by: Thomas Richter Signed-off-by: Vasily Gorbik