diff options
| author | Heiko Carstens <hca@linux.ibm.com> | 2025-03-10 10:33:39 +0100 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2025-03-18 17:13:04 +0100 |
| commit | 65c07e91cc31700ca8484d3bcd96e49b0053b57b (patch) | |
| tree | 28273f5fef4d096ef54d6ea312c635603f7d5256 | |
| parent | 430693c836c3828c72db2e1b1a7d2ddc97509cb8 (diff) | |
s390/current: Implement current with inline assembly
Implement current with an inline assembly, which makes use of the
ALTERNATIVE macro, to read current from lowcore. Provide an alternative
instruction with a different offset in case lowcore is relocated.
This replaces sequences of two instructions with one instruction.
Before:
100076: a5 1e 00 00 llilh %r1,0
10007a: e3 40 13 40 00 04 lg %r4,832(%r1)
After:
100076: e3 10 03 40 00 04 lg %r1,832
Kernel image size change:
add/remove: 3/17 grow/shrink: 166/2204 up/down: 7122/-24594 (-17472)
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
| -rw-r--r-- | arch/s390/include/asm/current.h | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/arch/s390/include/asm/current.h b/arch/s390/include/asm/current.h index d03a922c641e..f9529f7cf62c 100644 --- a/arch/s390/include/asm/current.h +++ b/arch/s390/include/asm/current.h @@ -11,9 +11,25 @@ #define _S390_CURRENT_H #include <asm/lowcore.h> +#include <asm/machine.h> struct task_struct; -#define current ((struct task_struct *const)get_lowcore()->current_task) +static __always_inline struct task_struct *get_current(void) +{ + unsigned long ptr, lc_current; + + lc_current = offsetof(struct lowcore, current_task); + asm_inline( + ALTERNATIVE(" lg %[ptr],%[offzero](%%r0)\n", + " lg %[ptr],%[offalt](%%r0)\n", + ALT_FEATURE(MFEATURE_LOWCORE)) + : [ptr] "=d" (ptr) + : [offzero] "i" (lc_current), + [offalt] "i" (lc_current + LOWCORE_ALT_ADDRESS)); + return (struct task_struct *)ptr; +} + +#define current get_current() #endif /* !(_S390_CURRENT_H) */ |