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linux-next/arch/x86/include/asm/jump_label.h
Masahiro Yamada e9666d10a5 jump_label: move 'asm goto' support test to Kconfig
Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label".

The jump label is controlled by HAVE_JUMP_LABEL, which is defined
like this:

  #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
  # define HAVE_JUMP_LABEL
  #endif

We can improve this by testing 'asm goto' support in Kconfig, then
make JUMP_LABEL depend on CC_HAS_ASM_GOTO.

Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will
match to the real kernel capability.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
2019-01-06 09:46:51 +09:00

93 lines
1.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_JUMP_LABEL_H
#define _ASM_X86_JUMP_LABEL_H
#define JUMP_LABEL_NOP_SIZE 5
#ifdef CONFIG_X86_64
# define STATIC_KEY_INIT_NOP P6_NOP5_ATOMIC
#else
# define STATIC_KEY_INIT_NOP GENERIC_NOP5_ATOMIC
#endif
#include <asm/asm.h>
#include <asm/nops.h>
#ifndef __ASSEMBLY__
#include <linux/stringify.h>
#include <linux/types.h>
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
asm_volatile_goto("1:"
".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
".pushsection __jump_table, \"aw\" \n\t"
_ASM_ALIGN "\n\t"
".long 1b - ., %l[l_yes] - . \n\t"
_ASM_PTR "%c0 + %c1 - .\n\t"
".popsection \n\t"
: : "i" (key), "i" (branch) : : l_yes);
return false;
l_yes:
return true;
}
static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
{
asm_volatile_goto("1:"
".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t"
"2:\n\t"
".pushsection __jump_table, \"aw\" \n\t"
_ASM_ALIGN "\n\t"
".long 1b - ., %l[l_yes] - . \n\t"
_ASM_PTR "%c0 + %c1 - .\n\t"
".popsection \n\t"
: : "i" (key), "i" (branch) : : l_yes);
return false;
l_yes:
return true;
}
#else /* __ASSEMBLY__ */
.macro STATIC_JUMP_IF_TRUE target, key, def
.Lstatic_jump_\@:
.if \def
/* Equivalent to "jmp.d32 \target" */
.byte 0xe9
.long \target - .Lstatic_jump_after_\@
.Lstatic_jump_after_\@:
.else
.byte STATIC_KEY_INIT_NOP
.endif
.pushsection __jump_table, "aw"
_ASM_ALIGN
.long .Lstatic_jump_\@ - ., \target - .
_ASM_PTR \key - .
.popsection
.endm
.macro STATIC_JUMP_IF_FALSE target, key, def
.Lstatic_jump_\@:
.if \def
.byte STATIC_KEY_INIT_NOP
.else
/* Equivalent to "jmp.d32 \target" */
.byte 0xe9
.long \target - .Lstatic_jump_after_\@
.Lstatic_jump_after_\@:
.endif
.pushsection __jump_table, "aw"
_ASM_ALIGN
.long .Lstatic_jump_\@ - ., \target - .
_ASM_PTR \key + 1 - .
.popsection
.endm
#endif /* __ASSEMBLY__ */
#endif