diff options
| author | Heiko Carstens <hca@linux.ibm.com> | 2025-03-17 16:22:35 +0100 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2025-03-18 17:13:51 +0100 |
| commit | 0dafe9968ac7c78c67ee6bb2d970d413fb493b95 (patch) | |
| tree | 59330732deed22efe980035096e3c26e6e4887b2 /arch/s390/kernel | |
| parent | caa3cd5ccd016cb28294e2b7e21fe08831e9a877 (diff) | |
s390: Use inline qualifier for all EX_TABLE and ALTERNATIVE inline assemblies
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 <jchrist@linux.ibm.com>
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/kernel')
| -rw-r--r-- | arch/s390/kernel/cert_store.c | 2 | ||||
| -rw-r--r-- | arch/s390/kernel/diag/diag.c | 4 | ||||
| -rw-r--r-- | arch/s390/kernel/ipl.c | 2 | ||||
| -rw-r--r-- | arch/s390/kernel/traps.c | 2 |
4 files changed, 5 insertions, 5 deletions
diff --git a/arch/s390/kernel/cert_store.c b/arch/s390/kernel/cert_store.c index bf983513dd33..03f3a1e52430 100644 --- a/arch/s390/kernel/cert_store.c +++ b/arch/s390/kernel/cert_store.c @@ -235,7 +235,7 @@ static int __diag320(unsigned long subcode, void *addr) { union register_pair rp = { .even = (unsigned long)addr, }; - asm volatile( + asm_inline volatile( " diag %[rp],%[subcode],0x320\n" "0: nopr %%r7\n" EX_TABLE(0b, 0b) diff --git a/arch/s390/kernel/diag/diag.c b/arch/s390/kernel/diag/diag.c index e15b8dee3228..56b862ba9be8 100644 --- a/arch/s390/kernel/diag/diag.c +++ b/arch/s390/kernel/diag/diag.c @@ -195,7 +195,7 @@ static inline int __diag204(unsigned long *subcode, unsigned long size, void *ad { union register_pair rp = { .even = *subcode, .odd = size }; - asm volatile( + asm_inline volatile( " diag %[addr],%[rp],0x204\n" "0: nopr %%r7\n" EX_TABLE(0b,0b) @@ -286,7 +286,7 @@ int diag224(void *ptr) int rc = -EOPNOTSUPP; diag_stat_inc(DIAG_STAT_X224); - asm volatile("\n" + asm_inline volatile("\n" " diag %[type],%[addr],0x224\n" "0: lhi %[rc],0\n" "1:\n" diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c index 8990e2dffcdf..3b9d9ccfad63 100644 --- a/arch/s390/kernel/ipl.c +++ b/arch/s390/kernel/ipl.c @@ -186,7 +186,7 @@ static inline int __diag308(unsigned long subcode, unsigned long addr) r1.even = addr; r1.odd = 0; - asm volatile( + asm_inline volatile( " diag %[r1],%[subcode],0x308\n" "0: nopr %%r7\n" EX_TABLE(0b,0b) diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c index 4daa3c76e999..9705929d256f 100644 --- a/arch/s390/kernel/traps.c +++ b/arch/s390/kernel/traps.c @@ -257,7 +257,7 @@ static void __init test_monitor_call(void) if (!IS_ENABLED(CONFIG_BUG)) return; - asm volatile( + asm_inline volatile( " mc 0,0\n" "0: xgr %0,%0\n" "1:\n" |