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s390: Add runtime constant support

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Implement the runtime constant infrastructure for s390, allowing the
dcache d_hash() function to be generated using as a constant for hash
table address followed by shift by a constant of the hash index.

This is the s390 variant of commit 94a2bc0f611c ("arm64: add 'runtime
constant' support") and commit e3c92e81711d ("runtime constants: add
x86 architecture support").

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2024-07-15 10:33:06 +02:00 committed by Vasily Gorbik
parent 66ebbdfdeb
commit 57e29f4c89
2 changed files with 80 additions and 0 deletions
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77
arch/s390/include/asm/runtime-const.h Normal file
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@ -0,0 +1,77 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_S390_RUNTIME_CONST_H
#define _ASM_S390_RUNTIME_CONST_H
#include <linux/uaccess.h>
#define runtime_const_ptr(sym) \
({ \
typeof(sym) __ret; \
\
asm_inline( \
"0: iihf %[__ret],%[c1]\n" \
" iilf %[__ret],%[c2]\n" \
".pushsection runtime_ptr_" #sym ",\"a\"\n" \
".long 0b - .\n" \
".popsection" \
: [__ret] "=d" (__ret) \
: [c1] "i" (0x01234567UL), \
[c2] "i" (0x89abcdefUL)); \
__ret; \
})
#define runtime_const_shift_right_32(val, sym) \
({ \
unsigned int __ret = (val); \
\
asm_inline( \
"0: srl %[__ret],12\n" \
".pushsection runtime_shift_" #sym ",\"a\"\n" \
".long 0b - .\n" \
".popsection" \
: [__ret] "+d" (__ret)); \
__ret; \
})
#define runtime_const_init(type, sym) do { \
extern s32 __start_runtime_##type##_##sym[]; \
extern s32 __stop_runtime_##type##_##sym[]; \
\
runtime_const_fixup(__runtime_fixup_##type, \
(unsigned long)(sym), \
__start_runtime_##type##_##sym, \
__stop_runtime_##type##_##sym); \
} while (0)
/* 32-bit immediate for iihf and iilf in bits in I2 field */
static inline void __runtime_fixup_32(u32 *p, unsigned int val)
{
s390_kernel_write(p, &val, sizeof(val));
}
static inline void __runtime_fixup_ptr(void *where, unsigned long val)
{
__runtime_fixup_32(where + 2, val >> 32);
__runtime_fixup_32(where + 8, val);
}
/* Immediate value is lower 12 bits of D2 field of srl */
static inline void __runtime_fixup_shift(void *where, unsigned long val)
{
u32 insn = *(u32 *)where;
insn &= 0xfffff000;
insn |= (val & 63);
s390_kernel_write(where, &insn, sizeof(insn));
}
static inline void runtime_const_fixup(void (*fn)(void *, unsigned long),
unsigned long val, s32 *start, s32 *end)
{
while (start < end) {
fn(*start + (void *)start, val);
start++;
}
}
#endif /* _ASM_S390_RUNTIME_CONST_H */

3
arch/s390/kernel/vmlinux.lds.S
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@ -190,6 +190,9 @@ SECTIONS
. = ALIGN(PAGE_SIZE);
INIT_DATA_SECTION(0x100)
RUNTIME_CONST(shift, d_hash_shift)
RUNTIME_CONST(ptr, dentry_hashtable)
PERCPU_SECTION(0x100)
. = ALIGN(PAGE_SIZE);