diff options
author | Olof Johansson <olof@lixom.net> | 2019-12-05 13:16:58 -0800 |
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committer | Olof Johansson <olof@lixom.net> | 2019-12-05 13:18:54 -0800 |
commit | 942e6f8a8314e5550e254519dfba4ccd5170421d (patch) | |
tree | 75ec655b440fbc1c454247af38b5596dd8c78de9 /arch/arc/include/asm/jump_label.h | |
parent | 336bab731be76a90291697e51d2aed0ad67d7cb5 (diff) | |
parent | b08baef02b26cf7c2123e4a24a2fa1fb7a593ffb (diff) |
Merge mainline/master into arm/fixes
This brings in the mainline tree right after armsoc contents was merged
this release cycle, so that we can re-run savedefconfig, etc.
Signed-off-by: Olof Johansson <olof@lixom.net>
Diffstat (limited to 'arch/arc/include/asm/jump_label.h')
-rw-r--r-- | arch/arc/include/asm/jump_label.h | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/arch/arc/include/asm/jump_label.h b/arch/arc/include/asm/jump_label.h new file mode 100644 index 000000000000..9d9618079739 --- /dev/null +++ b/arch/arc/include/asm/jump_label.h @@ -0,0 +1,72 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_ARC_JUMP_LABEL_H +#define _ASM_ARC_JUMP_LABEL_H + +#ifndef __ASSEMBLY__ + +#include <linux/stringify.h> +#include <linux/types.h> + +#define JUMP_LABEL_NOP_SIZE 4 + +/* + * NOTE about '.balign 4': + * + * To make atomic update of patched instruction available we need to guarantee + * that this instruction doesn't cross L1 cache line boundary. + * + * As of today we simply align instruction which can be patched by 4 byte using + * ".balign 4" directive. In that case patched instruction is aligned with one + * 16-bit NOP_S if this is required. + * However 'align by 4' directive is much stricter than it actually required. + * It's enough that our 32-bit instruction don't cross L1 cache line boundary / + * L1 I$ fetch block boundary which can be achieved by using + * ".bundle_align_mode" assembler directive. That will save us from adding + * useless NOP_S padding in most of the cases. + * + * TODO: switch to ".bundle_align_mode" directive using whin it will be + * supported by ARC toolchain. + */ + +static __always_inline bool arch_static_branch(struct static_key *key, + bool branch) +{ + asm_volatile_goto(".balign "__stringify(JUMP_LABEL_NOP_SIZE)" \n" + "1: \n" + "nop \n" + ".pushsection __jump_table, \"aw\" \n" + ".word 1b, %l[l_yes], %c0 \n" + ".popsection \n" + : : "i" (&((char *)key)[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(".balign "__stringify(JUMP_LABEL_NOP_SIZE)" \n" + "1: \n" + "b %l[l_yes] \n" + ".pushsection __jump_table, \"aw\" \n" + ".word 1b, %l[l_yes], %c0 \n" + ".popsection \n" + : : "i" (&((char *)key)[branch]) : : l_yes); + + return false; +l_yes: + return true; +} + +typedef u32 jump_label_t; + +struct jump_entry { + jump_label_t code; + jump_label_t target; + jump_label_t key; +}; + +#endif /* __ASSEMBLY__ */ +#endif |