Commit 94a2bc0f authored by Linus Torvalds's avatar Linus Torvalds
Browse files

arm64: add 'runtime constant' support 



This implements the runtime constant infrastructure for arm64, 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.

[ Fixed up to deal with the big-endian case as per Mark Rutland ]

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e3c92e81

arch/arm64/include/asm/runtime-const.h

0 → 100644
+88 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _ASM_RUNTIME_CONST_H

#define _ASM_RUNTIME_CONST_H



#include <asm/cacheflush.h>



/* Sigh. You can still run arm64 in BE mode */

#include <asm/byteorder.h>



#define runtime_const_ptr(sym) ({				\

	typeof(sym) __ret;					\

	asm_inline("1:\t"					\

		"movz %0, #0xcdef\n\t"				\

		"movk %0, #0x89ab, lsl #16\n\t"			\

		"movk %0, #0x4567, lsl #32\n\t"			\

		"movk %0, #0x0123, lsl #48\n\t"			\

		".pushsection runtime_ptr_" #sym ",\"a\"\n\t"	\

		".long 1b - .\n\t"				\

		".popsection"					\

		:"=r" (__ret));					\

	__ret; })



#define runtime_const_shift_right_32(val, sym) ({		\

	unsigned long __ret;					\

	asm_inline("1:\t"					\

		"lsr %w0,%w1,#12\n\t"				\

		".pushsection runtime_shift_" #sym ",\"a\"\n\t"	\

		".long 1b - .\n\t"				\

		".popsection"					\

		:"=r" (__ret)					\

		:"r" (0u+(val)));				\

	__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)



/* 16-bit immediate for wide move (movz and movk) in bits 5..20 */

static inline void __runtime_fixup_16(__le32 *p, unsigned int val)

{

	u32 insn = le32_to_cpu(*p);

	insn &= 0xffe0001f;

	insn |= (val & 0xffff) << 5;

	*p = cpu_to_le32(insn);

}



static inline void __runtime_fixup_caches(void *where, unsigned int insns)

{

	unsigned long va = (unsigned long)where;

	caches_clean_inval_pou(va, va + 4*insns);

}



static inline void __runtime_fixup_ptr(void *where, unsigned long val)

{

	__le32 *p = lm_alias(where);

	__runtime_fixup_16(p, val);

	__runtime_fixup_16(p+1, val >> 16);

	__runtime_fixup_16(p+2, val >> 32);

	__runtime_fixup_16(p+3, val >> 48);

	__runtime_fixup_caches(where, 4);

}



/* Immediate value is 6 bits starting at bit #16 */

static inline void __runtime_fixup_shift(void *where, unsigned long val)

{

	__le32 *p = lm_alias(where);

	u32 insn = le32_to_cpu(*p);

	insn &= 0xffc0ffff;

	insn |= (val & 63) << 16;

	*p = cpu_to_le32(insn);

	__runtime_fixup_caches(where, 1);

}



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

arch/arm64/kernel/vmlinux.lds.S

+3 −0
Original line number Diff line number Diff line
@@ -264,6 +264,9 @@ SECTIONS 
		EXIT_DATA

	}



	RUNTIME_CONST(shift, d_hash_shift)

	RUNTIME_CONST(ptr, dentry_hashtable)



	PERCPU_SECTION(L1_CACHE_BYTES)

	HYPERVISOR_PERCPU_SECTION