[PATCH] riscv: jump_label: Optimize size with RISCV_ISA_C
guoren at kernel.org
guoren at kernel.org
Sat Sep 17 11:17:42 PDT 2022
From: Guo Ren <guoren at linux.alibaba.com>
Reduce size of static branch.
Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
Signed-off-by: Guo Ren <guoren at kernel.org>
---
arch/riscv/include/asm/jump_label.h | 17 ++++++++++-----
arch/riscv/kernel/jump_label.c | 32 +++++++++++++++++++++++++++++
2 files changed, 44 insertions(+), 5 deletions(-)
diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
index 38af2ec7b9bf..78f747dfa8a2 100644
--- a/arch/riscv/include/asm/jump_label.h
+++ b/arch/riscv/include/asm/jump_label.h
@@ -12,17 +12,21 @@
#include <linux/types.h>
#include <asm/asm.h>
+#ifdef CONFIG_RISCV_ISA_C
+#define JUMP_LABEL_NOP_SIZE 2
+#else
#define JUMP_LABEL_NOP_SIZE 4
+#endif
static __always_inline bool arch_static_branch(struct static_key *key,
bool branch)
{
asm_volatile_goto(
- " .option push \n\t"
- " .option norelax \n\t"
- " .option norvc \n\t"
+#ifdef CONFIG_RISCV_ISA_C
+ "1: c.nop \n\t"
+#else
"1: nop \n\t"
- " .option pop \n\t"
+#endif
" .pushsection __jump_table, \"aw\" \n\t"
" .align " RISCV_LGPTR " \n\t"
" .long 1b - ., %l[label] - . \n\t"
@@ -39,11 +43,14 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key,
bool branch)
{
asm_volatile_goto(
+#ifdef CONFIG_RISCV_ISA_C
+ "1: c.j %l[label] \n\t"
+#else
" .option push \n\t"
" .option norelax \n\t"
- " .option norvc \n\t"
"1: jal zero, %l[label] \n\t"
" .option pop \n\t"
+#endif
" .pushsection __jump_table, \"aw\" \n\t"
" .align " RISCV_LGPTR " \n\t"
" .long 1b - ., %l[label] - . \n\t"
diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
index e6694759dbd0..64a4e5df093d 100644
--- a/arch/riscv/kernel/jump_label.c
+++ b/arch/riscv/kernel/jump_label.c
@@ -11,21 +11,52 @@
#include <asm/bug.h>
#include <asm/patch.h>
+#ifdef CONFIG_RISCV_ISA_C
+#define RISCV_INSN_C_NOP 0x0001U
+#define RISCV_INSN_C_JAL 0xa001U
+#else
#define RISCV_INSN_NOP 0x00000013U
#define RISCV_INSN_JAL 0x0000006fU
+#endif
void arch_jump_label_transform(struct jump_entry *entry,
enum jump_label_type type)
{
void *addr = (void *)jump_entry_code(entry);
+#ifdef CONFIG_RISCV_ISA_C
+ u16 insn;
+#else
u32 insn;
+#endif
if (type == JUMP_LABEL_JMP) {
long offset = jump_entry_target(entry) - jump_entry_code(entry);
+#ifdef CONFIG_RISCV_ISA_C
+ if (WARN_ON(offset & 1 || offset < -2048 || offset >= 2048))
+ return;
+ /*
+ * 001 | imm[11|4|9:8|10|6|7|3:1|5] 01 - C.JAL
+ */
+ insn = RISCV_INSN_C_JAL |
+ (((u16)offset & GENMASK(5, 5)) >> (5 - 2)) |
+ (((u16)offset & GENMASK(3, 1)) << (3 - 1)) |
+ (((u16)offset & GENMASK(7, 7)) >> (7 - 6)) |
+ (((u16)offset & GENMASK(6, 6)) << (7 - 6)) |
+ (((u16)offset & GENMASK(10, 10)) >> (10 - 8)) |
+ (((u16)offset & GENMASK(9, 8)) << (9 - 8)) |
+ (((u16)offset & GENMASK(4, 4)) << (11 - 4)) |
+ (((u16)offset & GENMASK(11, 11)) << (12 - 11));
+ } else {
+ insn = RISCV_INSN_C_NOP;
+ }
+#else
if (WARN_ON(offset & 1 || offset < -524288 || offset >= 524288))
return;
+ /*
+ * imm[20|10:1|11|19:12] | rd | 1101111 - JAL
+ */
insn = RISCV_INSN_JAL |
(((u32)offset & GENMASK(19, 12)) << (12 - 12)) |
(((u32)offset & GENMASK(11, 11)) << (20 - 11)) |
@@ -34,6 +65,7 @@ void arch_jump_label_transform(struct jump_entry *entry,
} else {
insn = RISCV_INSN_NOP;
}
+#endif
mutex_lock(&text_mutex);
patch_text_nosync(addr, &insn, sizeof(insn));
--
2.36.1
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