Commit e7829855 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

runtime constants: add default dummy infrastructure 



This adds the initial dummy support for 'runtime constants' for when
an architecture doesn't actually support an implementation of fixing
up said runtime constants.

This ends up being the fallback to just using the variables as regular
__ro_after_init variables, and changes the dcache d_hash() function to
use this model.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e60cc611

fs/dcache.c

+10 −1
Original line number Diff line number Diff line
@@ -35,6 +35,8 @@ 
#include "internal.h"

#include "mount.h"



#include <asm/runtime-const.h>



/*

 * Usage:

 * dcache->d_inode->i_lock protects:
@@ -102,7 +104,8 @@ static struct hlist_bl_head *dentry_hashtable __ro_after_init; 


static inline struct hlist_bl_head *d_hash(unsigned long hashlen)

{

	return dentry_hashtable + ((u32)hashlen >> d_hash_shift);

	return runtime_const_ptr(dentry_hashtable) +

		runtime_const_shift_right_32(hashlen, d_hash_shift);

}



#define IN_LOOKUP_SHIFT 10
@@ -3129,6 +3132,9 @@ static void __init dcache_init_early(void) 
					0,

					0);

	d_hash_shift = 32 - d_hash_shift;



	runtime_const_init(shift, d_hash_shift);

	runtime_const_init(ptr, dentry_hashtable);

}



static void __init dcache_init(void)
@@ -3157,6 +3163,9 @@ static void __init dcache_init(void) 
					0,

					0);

	d_hash_shift = 32 - d_hash_shift;



	runtime_const_init(shift, d_hash_shift);

	runtime_const_init(ptr, dentry_hashtable);

}



/* SLAB cache for __getname() consumers */

include/asm-generic/Kbuild

+1 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ mandatory-y += pci.h 
mandatory-y += percpu.h

mandatory-y += pgalloc.h

mandatory-y += preempt.h

mandatory-y += runtime-const.h

mandatory-y += rwonce.h

mandatory-y += sections.h

mandatory-y += serial.h

include/asm-generic/runtime-const.h

0 → 100644
+15 −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



/*

 * This is the fallback for when the architecture doesn't

 * support the runtime const operations.

 *

 * We just use the actual symbols as-is.

 */

#define runtime_const_ptr(sym) (sym)

#define runtime_const_shift_right_32(val, sym) ((u32)(val)>>(sym))

#define runtime_const_init(type,sym) do { } while (0)



#endif

include/asm-generic/vmlinux.lds.h

+8 −0
Original line number Diff line number Diff line
@@ -944,6 +944,14 @@ 
#define CON_INITCALL							\

	BOUNDED_SECTION_POST_LABEL(.con_initcall.init, __con_initcall, _start, _end)



#define RUNTIME_NAME(t,x) runtime_##t##_##x



#define RUNTIME_CONST(t,x)						\

	. = ALIGN(8);							\

	RUNTIME_NAME(t,x) : AT(ADDR(RUNTIME_NAME(t,x)) - LOAD_OFFSET) {	\

		*(RUNTIME_NAME(t,x));					\

	}



/* Alignment must be consistent with (kunit_suite *) in include/kunit/test.h */

#define KUNIT_TABLE()							\

		. = ALIGN(8);						\