[-next,V2,2/2] riscv: jump_label: Using c.j for CONFIG_RISCV_ISA_C
Commit Message
From: Guo Ren <guoren@linux.alibaba.com>
Reduce the size of the static branch instruction and prevent atomic
update problems. It would also reduce the range from 1MB to 4KB.
The range of 4K is enough for static branch.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Jessica Clarke <jrtc27@jrtc27.com>
---
arch/riscv/include/asm/jump_label.h | 16 +++++++++++----
arch/riscv/kernel/jump_label.c | 30 +++++++++++++++++++++++++++--
2 files changed, 40 insertions(+), 6 deletions(-)
@@ -12,17 +12,23 @@
#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(
- " .align 2 \n\t"
" .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"
+#endif
" .option pop \n\t"
" .pushsection __jump_table, \"aw\" \n\t"
" .align " RISCV_LGPTR " \n\t"
@@ -40,11 +46,13 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key,
bool branch)
{
asm_volatile_goto(
- " .align 2 \n\t"
" .option push \n\t"
" .option norelax \n\t"
- " .option norvc \n\t"
+#ifdef CONFIG_RISCV_ISA_C
+ "1: c.j %l[label] \n\t"
+#else
"1: jal zero, %l[label] \n\t"
+#endif
" .option pop \n\t"
" .pushsection __jump_table, \"aw\" \n\t"
" .align " RISCV_LGPTR " \n\t"
@@ -11,26 +11,52 @@
#include <asm/bug.h>
#include <asm/patch.h>
+#ifdef CONFIG_RISCV_ISA_C
+#define RISCV_INSN_NOP 0x0001U
+#define RISCV_INSN_C_J 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);
-
- if (WARN_ON(offset & 1 || offset < -524288 || offset >= 524288))
+ if (WARN_ON(offset & 1 || offset < -2048 || offset >= 2048))
return;
+#ifdef CONFIG_RISCV_ISA_C
+ /*
+ * 001 | imm[11|4|9:8|10|6|7|3:1|5] 01 - C.J
+ */
+ insn = RISCV_INSN_C_J |
+ (((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
+ /*
+ * 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)) |
(((u32)offset & GENMASK(10, 1)) << (21 - 1)) |
(((u32)offset & GENMASK(20, 20)) << (31 - 20));
+#endif
} else {
insn = RISCV_INSN_NOP;
}