From: Guo Ren <guoren@kernel.org>
To: guoren@kernel.org
Cc: andy.chiu@sifive.com, aou@eecs.berkeley.edu, ardb@kernel.org,
greentime.hu@sifive.com, jbaron@akamai.com, jpoimboe@kernel.org,
kernel@esmil.dk, linux-riscv@lists.infradead.org,
mingo@redhat.com, palmer@dabbelt.com, paul.walmsley@sifive.com,
peterz@infradead.org, rostedt@goodmis.org, zong.li@sifive.com,
Guo Ren <guoren@linux.alibaba.com>
Subject: Re: [PATCH RFC v2 riscv/for-next 5/5] riscv: align arch_static_branch function
Date: Sun, 18 Sep 2022 07:59:12 +0800 [thread overview]
Message-ID: <CAJF2gTQE-ihzkYGf6QwfbT=WZPrTabc0SRet4N1w+5E-9esw3A@mail.gmail.com> (raw)
In-Reply-To: <20220917183849.589593-1-guoren@kernel.org>
On Sun, Sep 18, 2022 at 2:39 AM <guoren@kernel.org> wrote:
>
> From: Guo Ren <guoren@linux.alibaba.com>
>
> Reduce size of static branch.
>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@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"
We should check the range during compile time, here. Run-time checking
is the last and most painful method to prevent some errors.
> @@ -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))
For the unify, it also should be:
if (WARN_ON(offset & 1 || offset < -2048 || offset >= 2048))
After some tests, 2048 is enough for the current riscv Linux.
> 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
>
--
Best Regards
Guo Ren
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next prev parent reply other threads:[~2022-09-17 23:59 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-13 9:42 [PATCH RFC v2 riscv/for-next 0/5] Enable ftrace with kernel preemption for RISC-V Andy Chiu
2022-09-13 9:42 ` [PATCH RFC v2 riscv/for-next 1/5] riscv: align ftrace to 4 Byte boundary and increase ftrace prologue size Andy Chiu
2022-09-15 13:53 ` Guo Ren
2022-09-17 1:15 ` Andy Chiu
2022-09-13 9:42 ` [PATCH RFC v2 riscv/for-next 2/5] riscv: export patch_insn_write Andy Chiu
2022-09-13 9:42 ` [PATCH RFC v2 riscv/for-next 3/5] riscv: ftrace: use indirect jump to work with kernel preemption Andy Chiu
2022-09-14 13:45 ` Guo Ren
2022-09-15 13:30 ` Guo Ren
2022-09-17 1:04 ` Andy Chiu
2022-09-17 10:56 ` Guo Ren
2024-02-20 14:17 ` Evgenii Shatokhin
2022-09-13 9:42 ` [PATCH RFC v2 riscv/for-next 4/5] riscv: ftrace: do not use stop_machine to update code Andy Chiu
2022-09-13 9:42 ` [PATCH RFC v2 riscv/for-next 5/5] riscv: align arch_static_branch function Andy Chiu
2022-09-14 14:06 ` Guo Ren
2022-09-16 23:54 ` Andy Chiu
2022-09-17 0:22 ` Guo Ren
2022-09-17 18:17 ` [PATCH] riscv: jump_label: Optimize size with RISCV_ISA_C guoren
2022-09-17 18:38 ` [PATCH RFC v2 riscv/for-next 5/5] riscv: align arch_static_branch function guoren
2022-09-17 23:49 ` Guo Ren
2022-09-17 23:59 ` Guo Ren [this message]
2022-09-18 0:12 ` Jessica Clarke
2022-09-18 0:46 ` Guo Ren
2022-09-14 14:24 ` Jessica Clarke
2022-09-15 1:47 ` Guo Ren
2022-09-15 2:34 ` Jessica Clarke
2024-02-13 19:42 ` [PATCH RFC v2 riscv/for-next 0/5] Enable ftrace with kernel preemption for RISC-V Evgenii Shatokhin
2024-02-21 5:27 ` Andy Chiu
2024-02-21 16:55 ` Evgenii Shatokhin
2024-03-06 20:57 ` Alexandre Ghiti
2024-03-07 8:35 ` Evgenii Shatokhin
2024-03-07 12:27 ` Andy Chiu
2024-03-07 13:21 ` Alexandre Ghiti
2024-03-07 15:57 ` Samuel Holland
2024-03-11 14:24 ` Andy Chiu
2024-03-19 14:50 ` Alexandre Ghiti
2024-03-19 14:58 ` Conor Dooley
2024-03-20 16:37 ` Andy Chiu
2024-03-18 15:31 ` Andy Chiu
2024-03-19 15:32 ` Evgenii Shatokhin
2024-03-20 16:38 ` Andy Chiu
2024-03-19 17:37 ` Alexandre Ghiti
2024-03-20 16:36 ` Andy Chiu
2024-03-21 11:02 ` Alexandre Ghiti
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