* [PATCH v1] riscv: Add jump-label implementation
@ 2020-07-07 15:07 Emil Renner Berthing
2020-07-08 6:28 ` Björn Töpel
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Emil Renner Berthing @ 2020-07-07 15:07 UTC (permalink / raw)
To: linux-riscv
Cc: Emil Renner Berthing, Björn Töpel, Palmer Dabbelt,
Paul Walmsley, linux-doc, Jonathan Corbet, linux-kernel
Add jump-label implementation based on the ARM64 version.
Tested on the HiFive Unleashed board.
Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
---
Changes since RFC:
- Use RISCV_PTR and RISCV_LGPTR macros to match struct jump_table
also in 32bit kernels.
- Remove unneeded branch ? 1 : 0, thanks Björn
- Fix \n\n instead of \n\t mistake
.../core/jump-labels/arch-support.txt | 2 +-
arch/riscv/Kconfig | 2 +
arch/riscv/include/asm/jump_label.h | 59 +++++++++++++++++++
arch/riscv/kernel/Makefile | 2 +
arch/riscv/kernel/jump_label.c | 44 ++++++++++++++
5 files changed, 108 insertions(+), 1 deletion(-)
create mode 100644 arch/riscv/include/asm/jump_label.h
create mode 100644 arch/riscv/kernel/jump_label.c
diff --git a/Documentation/features/core/jump-labels/arch-support.txt b/Documentation/features/core/jump-labels/arch-support.txt
index 632a1c7aefa2..760243d18ed7 100644
--- a/Documentation/features/core/jump-labels/arch-support.txt
+++ b/Documentation/features/core/jump-labels/arch-support.txt
@@ -23,7 +23,7 @@
| openrisc: | TODO |
| parisc: | ok |
| powerpc: | ok |
- | riscv: | TODO |
+ | riscv: | ok |
| s390: | ok |
| sh: | TODO |
| sparc: | ok |
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index fd639937e251..d2f5c53fdc19 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -46,6 +46,8 @@ config RISCV
select GENERIC_TIME_VSYSCALL if MMU && 64BIT
select HANDLE_DOMAIN_IRQ
select HAVE_ARCH_AUDITSYSCALL
+ select HAVE_ARCH_JUMP_LABEL
+ select HAVE_ARCH_JUMP_LABEL_RELATIVE
select HAVE_ARCH_KASAN if MMU && 64BIT
select HAVE_ARCH_KGDB
select HAVE_ARCH_KGDB_QXFER_PKT
diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
new file mode 100644
index 000000000000..d5fb342bfccf
--- /dev/null
+++ b/arch/riscv/include/asm/jump_label.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2020 Emil Renner Berthing
+ *
+ * Based on arch/arm64/include/asm/jump_label.h
+ */
+#ifndef __ASM_JUMP_LABEL_H
+#define __ASM_JUMP_LABEL_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+
+#define JUMP_LABEL_NOP_SIZE 4
+
+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"
+ "1: nop \n\t"
+ " .option pop \n\t"
+ " .pushsection __jump_table, \"aw\" \n\t"
+ " .align " RISCV_LGPTR " \n\t"
+ " .long 1b - ., %l[label] - . \n\t"
+ " " RISCV_PTR " %0 - . \n\t"
+ " .popsection \n\t"
+ : : "i"(&((char *)key)[branch]) : : label);
+
+ return false;
+label:
+ return true;
+}
+
+static __always_inline bool arch_static_branch_jump(struct static_key *key,
+ bool branch)
+{
+ asm_volatile_goto(
+ " .option push \n\t"
+ " .option norelax \n\t"
+ " .option norvc \n\t"
+ "1: jal zero, %l[label] \n\t"
+ " .option pop \n\t"
+ " .pushsection __jump_table, \"aw\" \n\t"
+ " .align " RISCV_LGPTR " \n\t"
+ " .long 1b - ., %l[label] - . \n\t"
+ " " RISCV_PTR " %0 - . \n\t"
+ " .popsection \n\t"
+ : : "i"(&((char *)key)[branch]) : : label);
+
+ return false;
+label:
+ return true;
+}
+
+#endif /* __ASSEMBLY__ */
+#endif /* __ASM_JUMP_LABEL_H */
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index b355cf485671..a5287ab9f7f2 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -53,4 +53,6 @@ endif
obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o
obj-$(CONFIG_KGDB) += kgdb.o
+obj-$(CONFIG_JUMP_LABEL) += jump_label.o
+
clean:
diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
new file mode 100644
index 000000000000..55b2d742efe1
--- /dev/null
+++ b/arch/riscv/kernel/jump_label.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Emil Renner Berthing
+ *
+ * Based on arch/arm64/kernel/jump_label.c
+ */
+#include <linux/kernel.h>
+#include <linux/jump_label.h>
+#include <asm/patch.h>
+
+#define RISCV_INSN_NOP 0x00000013
+#define RISCV_INSN_JAL 0x0000006f
+
+void arch_jump_label_transform(struct jump_entry *entry,
+ enum jump_label_type type)
+{
+ void *addr = (void *)jump_entry_code(entry);
+ u32 insn;
+
+ if (type == JUMP_LABEL_JMP) {
+ u32 offset = jump_entry_target(entry) - jump_entry_code(entry);
+
+ insn = RISCV_INSN_JAL |
+ ((offset & GENMASK(19, 12)) << (12 - 12)) |
+ ((offset & GENMASK(11, 11)) << (20 - 11)) |
+ ((offset & GENMASK(10, 1)) << (21 - 1)) |
+ ((offset & GENMASK(20, 20)) << (31 - 20));
+ } else
+ insn = RISCV_INSN_NOP;
+
+ patch_text_nosync(addr, &insn, sizeof(insn));
+}
+
+void arch_jump_label_transform_static(struct jump_entry *entry,
+ enum jump_label_type type)
+{
+ /*
+ * We use the same instructions in the arch_static_branch and
+ * arch_static_branch_jump inline functions, so there's no
+ * need to patch them up here.
+ * The core will call arch_jump_label_transform when those
+ * instructions need to be replaced.
+ */
+}
--
2.27.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v1] riscv: Add jump-label implementation
2020-07-07 15:07 [PATCH v1] riscv: Add jump-label implementation Emil Renner Berthing
@ 2020-07-08 6:28 ` Björn Töpel
2020-07-08 9:43 ` Emil Renner Berthing
2020-07-08 7:19 ` Björn Töpel
2020-07-08 7:42 ` Björn Töpel
2 siblings, 1 reply; 6+ messages in thread
From: Björn Töpel @ 2020-07-08 6:28 UTC (permalink / raw)
To: Emil Renner Berthing
Cc: linux-riscv, Palmer Dabbelt, Paul Walmsley, linux-doc,
Jonathan Corbet, LKML
On Tue, 7 Jul 2020 at 17:08, Emil Renner Berthing <kernel@esmil.dk> wrote:
>
> Add jump-label implementation based on the ARM64 version.
>
Thanks for working on this!
> Tested on the HiFive Unleashed board.
>
> Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> ---
>
> Changes since RFC:
> - Use RISCV_PTR and RISCV_LGPTR macros to match struct jump_table
> also in 32bit kernels.
> - Remove unneeded branch ? 1 : 0, thanks Björn
> - Fix \n\n instead of \n\t mistake
>
> .../core/jump-labels/arch-support.txt | 2 +-
> arch/riscv/Kconfig | 2 +
> arch/riscv/include/asm/jump_label.h | 59 +++++++++++++++++++
> arch/riscv/kernel/Makefile | 2 +
> arch/riscv/kernel/jump_label.c | 44 ++++++++++++++
> 5 files changed, 108 insertions(+), 1 deletion(-)
> create mode 100644 arch/riscv/include/asm/jump_label.h
> create mode 100644 arch/riscv/kernel/jump_label.c
>
> diff --git a/Documentation/features/core/jump-labels/arch-support.txt b/Documentation/features/core/jump-labels/arch-support.txt
> index 632a1c7aefa2..760243d18ed7 100644
> --- a/Documentation/features/core/jump-labels/arch-support.txt
> +++ b/Documentation/features/core/jump-labels/arch-support.txt
> @@ -23,7 +23,7 @@
> | openrisc: | TODO |
> | parisc: | ok |
> | powerpc: | ok |
> - | riscv: | TODO |
> + | riscv: | ok |
> | s390: | ok |
> | sh: | TODO |
> | sparc: | ok |
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index fd639937e251..d2f5c53fdc19 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -46,6 +46,8 @@ config RISCV
> select GENERIC_TIME_VSYSCALL if MMU && 64BIT
> select HANDLE_DOMAIN_IRQ
> select HAVE_ARCH_AUDITSYSCALL
> + select HAVE_ARCH_JUMP_LABEL
> + select HAVE_ARCH_JUMP_LABEL_RELATIVE
> select HAVE_ARCH_KASAN if MMU && 64BIT
> select HAVE_ARCH_KGDB
> select HAVE_ARCH_KGDB_QXFER_PKT
> diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
> new file mode 100644
> index 000000000000..d5fb342bfccf
> --- /dev/null
> +++ b/arch/riscv/include/asm/jump_label.h
> @@ -0,0 +1,59 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2020 Emil Renner Berthing
> + *
> + * Based on arch/arm64/include/asm/jump_label.h
> + */
> +#ifndef __ASM_JUMP_LABEL_H
> +#define __ASM_JUMP_LABEL_H
> +
> +#ifndef __ASSEMBLY__
> +
> +#include <linux/types.h>
> +
> +#define JUMP_LABEL_NOP_SIZE 4
> +
> +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"
> + "1: nop \n\t"
> + " .option pop \n\t"
> + " .pushsection __jump_table, \"aw\" \n\t"
> + " .align " RISCV_LGPTR " \n\t"
> + " .long 1b - ., %l[label] - . \n\t"
> + " " RISCV_PTR " %0 - . \n\t"
> + " .popsection \n\t"
> + : : "i"(&((char *)key)[branch]) : : label);
> +
> + return false;
> +label:
> + return true;
> +}
> +
> +static __always_inline bool arch_static_branch_jump(struct static_key *key,
> + bool branch)
> +{
> + asm_volatile_goto(
> + " .option push \n\t"
> + " .option norelax \n\t"
> + " .option norvc \n\t"
> + "1: jal zero, %l[label] \n\t"
> + " .option pop \n\t"
> + " .pushsection __jump_table, \"aw\" \n\t"
> + " .align " RISCV_LGPTR " \n\t"
> + " .long 1b - ., %l[label] - . \n\t"
> + " " RISCV_PTR " %0 - . \n\t"
> + " .popsection \n\t"
> + : : "i"(&((char *)key)[branch]) : : label);
> +
> + return false;
> +label:
> + return true;
> +}
> +
> +#endif /* __ASSEMBLY__ */
> +#endif /* __ASM_JUMP_LABEL_H */
> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> index b355cf485671..a5287ab9f7f2 100644
> --- a/arch/riscv/kernel/Makefile
> +++ b/arch/riscv/kernel/Makefile
> @@ -53,4 +53,6 @@ endif
> obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o
> obj-$(CONFIG_KGDB) += kgdb.o
>
> +obj-$(CONFIG_JUMP_LABEL) += jump_label.o
> +
> clean:
> diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
> new file mode 100644
> index 000000000000..55b2d742efe1
> --- /dev/null
> +++ b/arch/riscv/kernel/jump_label.c
> @@ -0,0 +1,44 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2020 Emil Renner Berthing
> + *
> + * Based on arch/arm64/kernel/jump_label.c
> + */
> +#include <linux/kernel.h>
> +#include <linux/jump_label.h>
> +#include <asm/patch.h>
> +
> +#define RISCV_INSN_NOP 0x00000013
> +#define RISCV_INSN_JAL 0x0000006f
> +
> +void arch_jump_label_transform(struct jump_entry *entry,
> + enum jump_label_type type)
> +{
> + void *addr = (void *)jump_entry_code(entry);
> + u32 insn;
> +
> + if (type == JUMP_LABEL_JMP) {
> + u32 offset = jump_entry_target(entry) - jump_entry_code(entry);
The 20b jump offset of JAL is enough, but to catch future changes that
might potentially break this, I would add a WARN to catch if offset
>20b (or overkill fallback to JALR -- don't do that.).
Somewhat related to that; The UNIX specification for RISC-V requires
support for RVC. Would it make sense to use the C.-instructions C.J
and C.NOP? Really a nit, or more of a question. I'm fine with this 32b
version!
> +
> + insn = RISCV_INSN_JAL |
> + ((offset & GENMASK(19, 12)) << (12 - 12)) |
> + ((offset & GENMASK(11, 11)) << (20 - 11)) |
> + ((offset & GENMASK(10, 1)) << (21 - 1)) |
> + ((offset & GENMASK(20, 20)) << (31 - 20));
> + } else
> + insn = RISCV_INSN_NOP;
Since the if-statement needs {}, the else-clause should have one too.
Feel free to add:
Reviewed-by: Björn Töpel <bjorn.topel@gmail.com>
Cheers,
Björn
> +
> + patch_text_nosync(addr, &insn, sizeof(insn));
> +}
> +
> +void arch_jump_label_transform_static(struct jump_entry *entry,
> + enum jump_label_type type)
> +{
> + /*
> + * We use the same instructions in the arch_static_branch and
> + * arch_static_branch_jump inline functions, so there's no
> + * need to patch them up here.
> + * The core will call arch_jump_label_transform when those
> + * instructions need to be replaced.
> + */
> +}
> --
> 2.27.0
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1] riscv: Add jump-label implementation
2020-07-07 15:07 [PATCH v1] riscv: Add jump-label implementation Emil Renner Berthing
2020-07-08 6:28 ` Björn Töpel
@ 2020-07-08 7:19 ` Björn Töpel
2020-07-08 7:42 ` Björn Töpel
2 siblings, 0 replies; 6+ messages in thread
From: Björn Töpel @ 2020-07-08 7:19 UTC (permalink / raw)
To: Emil Renner Berthing
Cc: linux-riscv, Palmer Dabbelt, Paul Walmsley, linux-doc,
Jonathan Corbet, LKML
On Tue, 7 Jul 2020 at 17:08, Emil Renner Berthing <kernel@esmil.dk> wrote:
>
> Add jump-label implementation based on the ARM64 version.
>
> Tested on the HiFive Unleashed board.
>
> Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> ---
>
> Changes since RFC:
> - Use RISCV_PTR and RISCV_LGPTR macros to match struct jump_table
> also in 32bit kernels.
> - Remove unneeded branch ? 1 : 0, thanks Björn
> - Fix \n\n instead of \n\t mistake
>
> .../core/jump-labels/arch-support.txt | 2 +-
> arch/riscv/Kconfig | 2 +
> arch/riscv/include/asm/jump_label.h | 59 +++++++++++++++++++
> arch/riscv/kernel/Makefile | 2 +
> arch/riscv/kernel/jump_label.c | 44 ++++++++++++++
> 5 files changed, 108 insertions(+), 1 deletion(-)
> create mode 100644 arch/riscv/include/asm/jump_label.h
> create mode 100644 arch/riscv/kernel/jump_label.c
>
> diff --git a/Documentation/features/core/jump-labels/arch-support.txt b/Documentation/features/core/jump-labels/arch-support.txt
> index 632a1c7aefa2..760243d18ed7 100644
> --- a/Documentation/features/core/jump-labels/arch-support.txt
> +++ b/Documentation/features/core/jump-labels/arch-support.txt
> @@ -23,7 +23,7 @@
> | openrisc: | TODO |
> | parisc: | ok |
> | powerpc: | ok |
> - | riscv: | TODO |
> + | riscv: | ok |
> | s390: | ok |
> | sh: | TODO |
> | sparc: | ok |
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index fd639937e251..d2f5c53fdc19 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -46,6 +46,8 @@ config RISCV
> select GENERIC_TIME_VSYSCALL if MMU && 64BIT
> select HANDLE_DOMAIN_IRQ
> select HAVE_ARCH_AUDITSYSCALL
> + select HAVE_ARCH_JUMP_LABEL
> + select HAVE_ARCH_JUMP_LABEL_RELATIVE
Missed one thing in the last reply; Please update defconfig with
CONFIG_JUMP_LABEL=y.
Björn
> select HAVE_ARCH_KASAN if MMU && 64BIT
> select HAVE_ARCH_KGDB
> select HAVE_ARCH_KGDB_QXFER_PKT
> diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
> new file mode 100644
> index 000000000000..d5fb342bfccf
> --- /dev/null
> +++ b/arch/riscv/include/asm/jump_label.h
> @@ -0,0 +1,59 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2020 Emil Renner Berthing
> + *
> + * Based on arch/arm64/include/asm/jump_label.h
> + */
> +#ifndef __ASM_JUMP_LABEL_H
> +#define __ASM_JUMP_LABEL_H
> +
> +#ifndef __ASSEMBLY__
> +
> +#include <linux/types.h>
> +
> +#define JUMP_LABEL_NOP_SIZE 4
> +
> +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"
> + "1: nop \n\t"
> + " .option pop \n\t"
> + " .pushsection __jump_table, \"aw\" \n\t"
> + " .align " RISCV_LGPTR " \n\t"
> + " .long 1b - ., %l[label] - . \n\t"
> + " " RISCV_PTR " %0 - . \n\t"
> + " .popsection \n\t"
> + : : "i"(&((char *)key)[branch]) : : label);
> +
> + return false;
> +label:
> + return true;
> +}
> +
> +static __always_inline bool arch_static_branch_jump(struct static_key *key,
> + bool branch)
> +{
> + asm_volatile_goto(
> + " .option push \n\t"
> + " .option norelax \n\t"
> + " .option norvc \n\t"
> + "1: jal zero, %l[label] \n\t"
> + " .option pop \n\t"
> + " .pushsection __jump_table, \"aw\" \n\t"
> + " .align " RISCV_LGPTR " \n\t"
> + " .long 1b - ., %l[label] - . \n\t"
> + " " RISCV_PTR " %0 - . \n\t"
> + " .popsection \n\t"
> + : : "i"(&((char *)key)[branch]) : : label);
> +
> + return false;
> +label:
> + return true;
> +}
> +
> +#endif /* __ASSEMBLY__ */
> +#endif /* __ASM_JUMP_LABEL_H */
> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> index b355cf485671..a5287ab9f7f2 100644
> --- a/arch/riscv/kernel/Makefile
> +++ b/arch/riscv/kernel/Makefile
> @@ -53,4 +53,6 @@ endif
> obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o
> obj-$(CONFIG_KGDB) += kgdb.o
>
> +obj-$(CONFIG_JUMP_LABEL) += jump_label.o
> +
> clean:
> diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
> new file mode 100644
> index 000000000000..55b2d742efe1
> --- /dev/null
> +++ b/arch/riscv/kernel/jump_label.c
> @@ -0,0 +1,44 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2020 Emil Renner Berthing
> + *
> + * Based on arch/arm64/kernel/jump_label.c
> + */
> +#include <linux/kernel.h>
> +#include <linux/jump_label.h>
> +#include <asm/patch.h>
> +
> +#define RISCV_INSN_NOP 0x00000013
> +#define RISCV_INSN_JAL 0x0000006f
> +
> +void arch_jump_label_transform(struct jump_entry *entry,
> + enum jump_label_type type)
> +{
> + void *addr = (void *)jump_entry_code(entry);
> + u32 insn;
> +
> + if (type == JUMP_LABEL_JMP) {
> + u32 offset = jump_entry_target(entry) - jump_entry_code(entry);
> +
> + insn = RISCV_INSN_JAL |
> + ((offset & GENMASK(19, 12)) << (12 - 12)) |
> + ((offset & GENMASK(11, 11)) << (20 - 11)) |
> + ((offset & GENMASK(10, 1)) << (21 - 1)) |
> + ((offset & GENMASK(20, 20)) << (31 - 20));
> + } else
> + insn = RISCV_INSN_NOP;
> +
> + patch_text_nosync(addr, &insn, sizeof(insn));
> +}
> +
> +void arch_jump_label_transform_static(struct jump_entry *entry,
> + enum jump_label_type type)
> +{
> + /*
> + * We use the same instructions in the arch_static_branch and
> + * arch_static_branch_jump inline functions, so there's no
> + * need to patch them up here.
> + * The core will call arch_jump_label_transform when those
> + * instructions need to be replaced.
> + */
> +}
> --
> 2.27.0
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1] riscv: Add jump-label implementation
2020-07-07 15:07 [PATCH v1] riscv: Add jump-label implementation Emil Renner Berthing
2020-07-08 6:28 ` Björn Töpel
2020-07-08 7:19 ` Björn Töpel
@ 2020-07-08 7:42 ` Björn Töpel
2020-07-08 9:45 ` Emil Renner Berthing
2 siblings, 1 reply; 6+ messages in thread
From: Björn Töpel @ 2020-07-08 7:42 UTC (permalink / raw)
To: Emil Renner Berthing
Cc: linux-riscv, Palmer Dabbelt, Paul Walmsley, linux-doc,
Jonathan Corbet, LKML
On Tue, 7 Jul 2020 at 17:08, Emil Renner Berthing <kernel@esmil.dk> wrote:
>
> Add jump-label implementation based on the ARM64 version.
>
> Tested on the HiFive Unleashed board.
>
I took your patch for a spin on qemu. The boot selftest
(CONFIG_STATIC_KEYS_SELFTEST=y) passes, but the module test
(CONFIG_TEST_STATIC_KEYS=m) does not.
When I run the in "test tools/testing/selftests/static_keys" (this
simply loads the test_static_key_base.ko and test_static_keys.ko
modules) I get:
[ 134.090464] test_static_keys: Unknown relocation type 36
36 is the relocation type R_RISCV_ADD64, which is not handled in
arch/riscv/kernel/module.c.
If you dump the relocation entries for test_static_keys.ko
(riscv64-linux-gnu-objdump -r test_static_keys.ko), you'll see that:
RELOCATION RECORDS FOR [__jump_table]:
OFFSET TYPE VALUE
0000000000000000 R_RISCV_ADD32 .L1^B1
0000000000000000 R_RISCV_SUB32 .L0
0000000000000004 R_RISCV_ADD32 .L3
0000000000000004 R_RISCV_SUB32 .L0
0000000000000008 R_RISCV_ADD64 old_true_key+0x0000000000000001
0000000000000008 R_RISCV_SUB64 .L0
...
It would be great if you could add a patch for that as well (separate,
same series). R_RISCV_ADD64 *and* R_RISCV_SUB64 are currently
unhandled by module.c.
Cheers,
Björn
> Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> ---
>
> Changes since RFC:
> - Use RISCV_PTR and RISCV_LGPTR macros to match struct jump_table
> also in 32bit kernels.
> - Remove unneeded branch ? 1 : 0, thanks Björn
> - Fix \n\n instead of \n\t mistake
>
> .../core/jump-labels/arch-support.txt | 2 +-
> arch/riscv/Kconfig | 2 +
> arch/riscv/include/asm/jump_label.h | 59 +++++++++++++++++++
> arch/riscv/kernel/Makefile | 2 +
> arch/riscv/kernel/jump_label.c | 44 ++++++++++++++
> 5 files changed, 108 insertions(+), 1 deletion(-)
> create mode 100644 arch/riscv/include/asm/jump_label.h
> create mode 100644 arch/riscv/kernel/jump_label.c
>
> diff --git a/Documentation/features/core/jump-labels/arch-support.txt b/Documentation/features/core/jump-labels/arch-support.txt
> index 632a1c7aefa2..760243d18ed7 100644
> --- a/Documentation/features/core/jump-labels/arch-support.txt
> +++ b/Documentation/features/core/jump-labels/arch-support.txt
> @@ -23,7 +23,7 @@
> | openrisc: | TODO |
> | parisc: | ok |
> | powerpc: | ok |
> - | riscv: | TODO |
> + | riscv: | ok |
> | s390: | ok |
> | sh: | TODO |
> | sparc: | ok |
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index fd639937e251..d2f5c53fdc19 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -46,6 +46,8 @@ config RISCV
> select GENERIC_TIME_VSYSCALL if MMU && 64BIT
> select HANDLE_DOMAIN_IRQ
> select HAVE_ARCH_AUDITSYSCALL
> + select HAVE_ARCH_JUMP_LABEL
> + select HAVE_ARCH_JUMP_LABEL_RELATIVE
> select HAVE_ARCH_KASAN if MMU && 64BIT
> select HAVE_ARCH_KGDB
> select HAVE_ARCH_KGDB_QXFER_PKT
> diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
> new file mode 100644
> index 000000000000..d5fb342bfccf
> --- /dev/null
> +++ b/arch/riscv/include/asm/jump_label.h
> @@ -0,0 +1,59 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (C) 2020 Emil Renner Berthing
> + *
> + * Based on arch/arm64/include/asm/jump_label.h
> + */
> +#ifndef __ASM_JUMP_LABEL_H
> +#define __ASM_JUMP_LABEL_H
> +
> +#ifndef __ASSEMBLY__
> +
> +#include <linux/types.h>
> +
> +#define JUMP_LABEL_NOP_SIZE 4
> +
> +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"
> + "1: nop \n\t"
> + " .option pop \n\t"
> + " .pushsection __jump_table, \"aw\" \n\t"
> + " .align " RISCV_LGPTR " \n\t"
> + " .long 1b - ., %l[label] - . \n\t"
> + " " RISCV_PTR " %0 - . \n\t"
> + " .popsection \n\t"
> + : : "i"(&((char *)key)[branch]) : : label);
> +
> + return false;
> +label:
> + return true;
> +}
> +
> +static __always_inline bool arch_static_branch_jump(struct static_key *key,
> + bool branch)
> +{
> + asm_volatile_goto(
> + " .option push \n\t"
> + " .option norelax \n\t"
> + " .option norvc \n\t"
> + "1: jal zero, %l[label] \n\t"
> + " .option pop \n\t"
> + " .pushsection __jump_table, \"aw\" \n\t"
> + " .align " RISCV_LGPTR " \n\t"
> + " .long 1b - ., %l[label] - . \n\t"
> + " " RISCV_PTR " %0 - . \n\t"
> + " .popsection \n\t"
> + : : "i"(&((char *)key)[branch]) : : label);
> +
> + return false;
> +label:
> + return true;
> +}
> +
> +#endif /* __ASSEMBLY__ */
> +#endif /* __ASM_JUMP_LABEL_H */
> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> index b355cf485671..a5287ab9f7f2 100644
> --- a/arch/riscv/kernel/Makefile
> +++ b/arch/riscv/kernel/Makefile
> @@ -53,4 +53,6 @@ endif
> obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o
> obj-$(CONFIG_KGDB) += kgdb.o
>
> +obj-$(CONFIG_JUMP_LABEL) += jump_label.o
> +
> clean:
> diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
> new file mode 100644
> index 000000000000..55b2d742efe1
> --- /dev/null
> +++ b/arch/riscv/kernel/jump_label.c
> @@ -0,0 +1,44 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2020 Emil Renner Berthing
> + *
> + * Based on arch/arm64/kernel/jump_label.c
> + */
> +#include <linux/kernel.h>
> +#include <linux/jump_label.h>
> +#include <asm/patch.h>
> +
> +#define RISCV_INSN_NOP 0x00000013
> +#define RISCV_INSN_JAL 0x0000006f
> +
> +void arch_jump_label_transform(struct jump_entry *entry,
> + enum jump_label_type type)
> +{
> + void *addr = (void *)jump_entry_code(entry);
> + u32 insn;
> +
> + if (type == JUMP_LABEL_JMP) {
> + u32 offset = jump_entry_target(entry) - jump_entry_code(entry);
> +
> + insn = RISCV_INSN_JAL |
> + ((offset & GENMASK(19, 12)) << (12 - 12)) |
> + ((offset & GENMASK(11, 11)) << (20 - 11)) |
> + ((offset & GENMASK(10, 1)) << (21 - 1)) |
> + ((offset & GENMASK(20, 20)) << (31 - 20));
> + } else
> + insn = RISCV_INSN_NOP;
> +
> + patch_text_nosync(addr, &insn, sizeof(insn));
> +}
> +
> +void arch_jump_label_transform_static(struct jump_entry *entry,
> + enum jump_label_type type)
> +{
> + /*
> + * We use the same instructions in the arch_static_branch and
> + * arch_static_branch_jump inline functions, so there's no
> + * need to patch them up here.
> + * The core will call arch_jump_label_transform when those
> + * instructions need to be replaced.
> + */
> +}
> --
> 2.27.0
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1] riscv: Add jump-label implementation
2020-07-08 6:28 ` Björn Töpel
@ 2020-07-08 9:43 ` Emil Renner Berthing
0 siblings, 0 replies; 6+ messages in thread
From: Emil Renner Berthing @ 2020-07-08 9:43 UTC (permalink / raw)
To: Björn Töpel
Cc: linux-riscv, Palmer Dabbelt, Paul Walmsley, linux-doc,
Jonathan Corbet, LKML
On Wed, 8 Jul 2020 at 08:28, Björn Töpel <bjorn.topel@gmail.com> wrote:
> On Tue, 7 Jul 2020 at 17:08, Emil Renner Berthing <kernel@esmil.dk> wrote:
> >
> > Add jump-label implementation based on the ARM64 version.
> >
>
> Thanks for working on this!
>
> > Tested on the HiFive Unleashed board.
> >
> > Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> > ---
> >
> > Changes since RFC:
> > - Use RISCV_PTR and RISCV_LGPTR macros to match struct jump_table
> > also in 32bit kernels.
> > - Remove unneeded branch ? 1 : 0, thanks Björn
> > - Fix \n\n instead of \n\t mistake
> >
> > .../core/jump-labels/arch-support.txt | 2 +-
> > arch/riscv/Kconfig | 2 +
> > arch/riscv/include/asm/jump_label.h | 59 +++++++++++++++++++
> > arch/riscv/kernel/Makefile | 2 +
> > arch/riscv/kernel/jump_label.c | 44 ++++++++++++++
> > 5 files changed, 108 insertions(+), 1 deletion(-)
> > create mode 100644 arch/riscv/include/asm/jump_label.h
> > create mode 100644 arch/riscv/kernel/jump_label.c
> >
> > diff --git a/Documentation/features/core/jump-labels/arch-support.txt b/Documentation/features/core/jump-labels/arch-support.txt
> > index 632a1c7aefa2..760243d18ed7 100644
> > --- a/Documentation/features/core/jump-labels/arch-support.txt
> > +++ b/Documentation/features/core/jump-labels/arch-support.txt
> > @@ -23,7 +23,7 @@
> > | openrisc: | TODO |
> > | parisc: | ok |
> > | powerpc: | ok |
> > - | riscv: | TODO |
> > + | riscv: | ok |
> > | s390: | ok |
> > | sh: | TODO |
> > | sparc: | ok |
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index fd639937e251..d2f5c53fdc19 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -46,6 +46,8 @@ config RISCV
> > select GENERIC_TIME_VSYSCALL if MMU && 64BIT
> > select HANDLE_DOMAIN_IRQ
> > select HAVE_ARCH_AUDITSYSCALL
> > + select HAVE_ARCH_JUMP_LABEL
> > + select HAVE_ARCH_JUMP_LABEL_RELATIVE
> > select HAVE_ARCH_KASAN if MMU && 64BIT
> > select HAVE_ARCH_KGDB
> > select HAVE_ARCH_KGDB_QXFER_PKT
> > diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
> > new file mode 100644
> > index 000000000000..d5fb342bfccf
> > --- /dev/null
> > +++ b/arch/riscv/include/asm/jump_label.h
> > @@ -0,0 +1,59 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright (C) 2020 Emil Renner Berthing
> > + *
> > + * Based on arch/arm64/include/asm/jump_label.h
> > + */
> > +#ifndef __ASM_JUMP_LABEL_H
> > +#define __ASM_JUMP_LABEL_H
> > +
> > +#ifndef __ASSEMBLY__
> > +
> > +#include <linux/types.h>
> > +
> > +#define JUMP_LABEL_NOP_SIZE 4
> > +
> > +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"
> > + "1: nop \n\t"
> > + " .option pop \n\t"
> > + " .pushsection __jump_table, \"aw\" \n\t"
> > + " .align " RISCV_LGPTR " \n\t"
> > + " .long 1b - ., %l[label] - . \n\t"
> > + " " RISCV_PTR " %0 - . \n\t"
> > + " .popsection \n\t"
> > + : : "i"(&((char *)key)[branch]) : : label);
> > +
> > + return false;
> > +label:
> > + return true;
> > +}
> > +
> > +static __always_inline bool arch_static_branch_jump(struct static_key *key,
> > + bool branch)
> > +{
> > + asm_volatile_goto(
> > + " .option push \n\t"
> > + " .option norelax \n\t"
> > + " .option norvc \n\t"
> > + "1: jal zero, %l[label] \n\t"
> > + " .option pop \n\t"
> > + " .pushsection __jump_table, \"aw\" \n\t"
> > + " .align " RISCV_LGPTR " \n\t"
> > + " .long 1b - ., %l[label] - . \n\t"
> > + " " RISCV_PTR " %0 - . \n\t"
> > + " .popsection \n\t"
> > + : : "i"(&((char *)key)[branch]) : : label);
> > +
> > + return false;
> > +label:
> > + return true;
> > +}
> > +
> > +#endif /* __ASSEMBLY__ */
> > +#endif /* __ASM_JUMP_LABEL_H */
> > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> > index b355cf485671..a5287ab9f7f2 100644
> > --- a/arch/riscv/kernel/Makefile
> > +++ b/arch/riscv/kernel/Makefile
> > @@ -53,4 +53,6 @@ endif
> > obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o
> > obj-$(CONFIG_KGDB) += kgdb.o
> >
> > +obj-$(CONFIG_JUMP_LABEL) += jump_label.o
> > +
> > clean:
> > diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
> > new file mode 100644
> > index 000000000000..55b2d742efe1
> > --- /dev/null
> > +++ b/arch/riscv/kernel/jump_label.c
> > @@ -0,0 +1,44 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (C) 2020 Emil Renner Berthing
> > + *
> > + * Based on arch/arm64/kernel/jump_label.c
> > + */
> > +#include <linux/kernel.h>
> > +#include <linux/jump_label.h>
> > +#include <asm/patch.h>
> > +
> > +#define RISCV_INSN_NOP 0x00000013
> > +#define RISCV_INSN_JAL 0x0000006f
> > +
> > +void arch_jump_label_transform(struct jump_entry *entry,
> > + enum jump_label_type type)
> > +{
> > + void *addr = (void *)jump_entry_code(entry);
> > + u32 insn;
> > +
> > + if (type == JUMP_LABEL_JMP) {
> > + u32 offset = jump_entry_target(entry) - jump_entry_code(entry);
>
> The 20b jump offset of JAL is enough, but to catch future changes that
> might potentially break this, I would add a WARN to catch if offset
> >20b (or overkill fallback to JALR -- don't do that.).
You're right. Not all architectures have warnings, but all arch's but
parisc and xtensa supports offsets > 20b. I'll add a WARN.
> Somewhat related to that; The UNIX specification for RISC-V requires
> support for RVC. Would it make sense to use the C.-instructions C.J
> and C.NOP? Really a nit, or more of a question. I'm fine with this 32b
> version!
That would definitely be possible, but then we only get 11b of offset
available. That's even lower than the 17b of parisc and xtensa. That
would probably need a CONFIG flag unless someone can come up with a
way to estimate the offset at compile time.
Alternatively I can't see a way that two compressed instructions could
combine to a jump with more than the 20b of offset, and I can't
imagine two compressed nops would be better than one 32b nop, so
unless you're willing to live with 11b offsets I think we're better
off with the 32b instructions.
> > +
> > + insn = RISCV_INSN_JAL |
> > + ((offset & GENMASK(19, 12)) << (12 - 12)) |
> > + ((offset & GENMASK(11, 11)) << (20 - 11)) |
> > + ((offset & GENMASK(10, 1)) << (21 - 1)) |
> > + ((offset & GENMASK(20, 20)) << (31 - 20));
> > + } else
> > + insn = RISCV_INSN_NOP;
>
> Since the if-statement needs {}, the else-clause should have one too.
Will fix.
> Feel free to add:
> Reviewed-by: Björn Töpel <bjorn.topel@gmail.com>
Thanks!
> Cheers,
> Björn
> > +
> > + patch_text_nosync(addr, &insn, sizeof(insn));
> > +}
> > +
> > +void arch_jump_label_transform_static(struct jump_entry *entry,
> > + enum jump_label_type type)
> > +{
> > + /*
> > + * We use the same instructions in the arch_static_branch and
> > + * arch_static_branch_jump inline functions, so there's no
> > + * need to patch them up here.
> > + * The core will call arch_jump_label_transform when those
> > + * instructions need to be replaced.
> > + */
> > +}
> > --
> > 2.27.0
> >
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v1] riscv: Add jump-label implementation
2020-07-08 7:42 ` Björn Töpel
@ 2020-07-08 9:45 ` Emil Renner Berthing
0 siblings, 0 replies; 6+ messages in thread
From: Emil Renner Berthing @ 2020-07-08 9:45 UTC (permalink / raw)
To: Björn Töpel
Cc: linux-riscv, Palmer Dabbelt, Paul Walmsley, linux-doc,
Jonathan Corbet, LKML
On Wed, 8 Jul 2020 at 09:42, Björn Töpel <bjorn.topel@gmail.com> wrote:
>
> On Tue, 7 Jul 2020 at 17:08, Emil Renner Berthing <kernel@esmil.dk> wrote:
> >
> > Add jump-label implementation based on the ARM64 version.
> >
> > Tested on the HiFive Unleashed board.
> >
>
> I took your patch for a spin on qemu. The boot selftest
> (CONFIG_STATIC_KEYS_SELFTEST=y) passes, but the module test
> (CONFIG_TEST_STATIC_KEYS=m) does not.
>
> When I run the in "test tools/testing/selftests/static_keys" (this
> simply loads the test_static_key_base.ko and test_static_keys.ko
> modules) I get:
>
> [ 134.090464] test_static_keys: Unknown relocation type 36
>
> 36 is the relocation type R_RISCV_ADD64, which is not handled in
> arch/riscv/kernel/module.c.
>
> If you dump the relocation entries for test_static_keys.ko
> (riscv64-linux-gnu-objdump -r test_static_keys.ko), you'll see that:
>
> RELOCATION RECORDS FOR [__jump_table]:
> OFFSET TYPE VALUE
> 0000000000000000 R_RISCV_ADD32 .L1^B1
> 0000000000000000 R_RISCV_SUB32 .L0
> 0000000000000004 R_RISCV_ADD32 .L3
> 0000000000000004 R_RISCV_SUB32 .L0
> 0000000000000008 R_RISCV_ADD64 old_true_key+0x0000000000000001
> 0000000000000008 R_RISCV_SUB64 .L0
> ...
>
> It would be great if you could add a patch for that as well (separate,
> same series). R_RISCV_ADD64 *and* R_RISCV_SUB64 are currently
> unhandled by module.c.
On it! I'll also add the CONFIG_JUMP_LABEL to defconfig to the next version.
>
> Cheers,
> Björn
>
> > Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> > ---
> >
> > Changes since RFC:
> > - Use RISCV_PTR and RISCV_LGPTR macros to match struct jump_table
> > also in 32bit kernels.
> > - Remove unneeded branch ? 1 : 0, thanks Björn
> > - Fix \n\n instead of \n\t mistake
> >
> > .../core/jump-labels/arch-support.txt | 2 +-
> > arch/riscv/Kconfig | 2 +
> > arch/riscv/include/asm/jump_label.h | 59 +++++++++++++++++++
> > arch/riscv/kernel/Makefile | 2 +
> > arch/riscv/kernel/jump_label.c | 44 ++++++++++++++
> > 5 files changed, 108 insertions(+), 1 deletion(-)
> > create mode 100644 arch/riscv/include/asm/jump_label.h
> > create mode 100644 arch/riscv/kernel/jump_label.c
> >
> > diff --git a/Documentation/features/core/jump-labels/arch-support.txt b/Documentation/features/core/jump-labels/arch-support.txt
> > index 632a1c7aefa2..760243d18ed7 100644
> > --- a/Documentation/features/core/jump-labels/arch-support.txt
> > +++ b/Documentation/features/core/jump-labels/arch-support.txt
> > @@ -23,7 +23,7 @@
> > | openrisc: | TODO |
> > | parisc: | ok |
> > | powerpc: | ok |
> > - | riscv: | TODO |
> > + | riscv: | ok |
> > | s390: | ok |
> > | sh: | TODO |
> > | sparc: | ok |
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index fd639937e251..d2f5c53fdc19 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -46,6 +46,8 @@ config RISCV
> > select GENERIC_TIME_VSYSCALL if MMU && 64BIT
> > select HANDLE_DOMAIN_IRQ
> > select HAVE_ARCH_AUDITSYSCALL
> > + select HAVE_ARCH_JUMP_LABEL
> > + select HAVE_ARCH_JUMP_LABEL_RELATIVE
> > select HAVE_ARCH_KASAN if MMU && 64BIT
> > select HAVE_ARCH_KGDB
> > select HAVE_ARCH_KGDB_QXFER_PKT
> > diff --git a/arch/riscv/include/asm/jump_label.h b/arch/riscv/include/asm/jump_label.h
> > new file mode 100644
> > index 000000000000..d5fb342bfccf
> > --- /dev/null
> > +++ b/arch/riscv/include/asm/jump_label.h
> > @@ -0,0 +1,59 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright (C) 2020 Emil Renner Berthing
> > + *
> > + * Based on arch/arm64/include/asm/jump_label.h
> > + */
> > +#ifndef __ASM_JUMP_LABEL_H
> > +#define __ASM_JUMP_LABEL_H
> > +
> > +#ifndef __ASSEMBLY__
> > +
> > +#include <linux/types.h>
> > +
> > +#define JUMP_LABEL_NOP_SIZE 4
> > +
> > +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"
> > + "1: nop \n\t"
> > + " .option pop \n\t"
> > + " .pushsection __jump_table, \"aw\" \n\t"
> > + " .align " RISCV_LGPTR " \n\t"
> > + " .long 1b - ., %l[label] - . \n\t"
> > + " " RISCV_PTR " %0 - . \n\t"
> > + " .popsection \n\t"
> > + : : "i"(&((char *)key)[branch]) : : label);
> > +
> > + return false;
> > +label:
> > + return true;
> > +}
> > +
> > +static __always_inline bool arch_static_branch_jump(struct static_key *key,
> > + bool branch)
> > +{
> > + asm_volatile_goto(
> > + " .option push \n\t"
> > + " .option norelax \n\t"
> > + " .option norvc \n\t"
> > + "1: jal zero, %l[label] \n\t"
> > + " .option pop \n\t"
> > + " .pushsection __jump_table, \"aw\" \n\t"
> > + " .align " RISCV_LGPTR " \n\t"
> > + " .long 1b - ., %l[label] - . \n\t"
> > + " " RISCV_PTR " %0 - . \n\t"
> > + " .popsection \n\t"
> > + : : "i"(&((char *)key)[branch]) : : label);
> > +
> > + return false;
> > +label:
> > + return true;
> > +}
> > +
> > +#endif /* __ASSEMBLY__ */
> > +#endif /* __ASM_JUMP_LABEL_H */
> > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> > index b355cf485671..a5287ab9f7f2 100644
> > --- a/arch/riscv/kernel/Makefile
> > +++ b/arch/riscv/kernel/Makefile
> > @@ -53,4 +53,6 @@ endif
> > obj-$(CONFIG_HOTPLUG_CPU) += cpu-hotplug.o
> > obj-$(CONFIG_KGDB) += kgdb.o
> >
> > +obj-$(CONFIG_JUMP_LABEL) += jump_label.o
> > +
> > clean:
> > diff --git a/arch/riscv/kernel/jump_label.c b/arch/riscv/kernel/jump_label.c
> > new file mode 100644
> > index 000000000000..55b2d742efe1
> > --- /dev/null
> > +++ b/arch/riscv/kernel/jump_label.c
> > @@ -0,0 +1,44 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (C) 2020 Emil Renner Berthing
> > + *
> > + * Based on arch/arm64/kernel/jump_label.c
> > + */
> > +#include <linux/kernel.h>
> > +#include <linux/jump_label.h>
> > +#include <asm/patch.h>
> > +
> > +#define RISCV_INSN_NOP 0x00000013
> > +#define RISCV_INSN_JAL 0x0000006f
> > +
> > +void arch_jump_label_transform(struct jump_entry *entry,
> > + enum jump_label_type type)
> > +{
> > + void *addr = (void *)jump_entry_code(entry);
> > + u32 insn;
> > +
> > + if (type == JUMP_LABEL_JMP) {
> > + u32 offset = jump_entry_target(entry) - jump_entry_code(entry);
> > +
> > + insn = RISCV_INSN_JAL |
> > + ((offset & GENMASK(19, 12)) << (12 - 12)) |
> > + ((offset & GENMASK(11, 11)) << (20 - 11)) |
> > + ((offset & GENMASK(10, 1)) << (21 - 1)) |
> > + ((offset & GENMASK(20, 20)) << (31 - 20));
> > + } else
> > + insn = RISCV_INSN_NOP;
> > +
> > + patch_text_nosync(addr, &insn, sizeof(insn));
> > +}
> > +
> > +void arch_jump_label_transform_static(struct jump_entry *entry,
> > + enum jump_label_type type)
> > +{
> > + /*
> > + * We use the same instructions in the arch_static_branch and
> > + * arch_static_branch_jump inline functions, so there's no
> > + * need to patch them up here.
> > + * The core will call arch_jump_label_transform when those
> > + * instructions need to be replaced.
> > + */
> > +}
> > --
> > 2.27.0
> >
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-07-08 9:45 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-07 15:07 [PATCH v1] riscv: Add jump-label implementation Emil Renner Berthing
2020-07-08 6:28 ` Björn Töpel
2020-07-08 9:43 ` Emil Renner Berthing
2020-07-08 7:19 ` Björn Töpel
2020-07-08 7:42 ` Björn Töpel
2020-07-08 9:45 ` Emil Renner Berthing
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).