[PATCH v2 0/2] riscv: improve __ex_table section handling

[PATCH v2 0/2] riscv: improve __ex_table section handling

[Jisheng Zhang]

From: Jisheng Zhang <jszhang@kernel.org>

Enable BUILDTIME_TABLE_SORT to sort the exception table at build time
then move exception table to RO_DATA segment.

Since v1:
  - Only enable BUILDTIME_TABLE_SORT for MMU. Thank Palmer for catching
    tinyconfig case.

Jisheng Zhang (2):
  riscv: Enable BUILDTIME_TABLE_SORT
  riscv: Move EXCEPTION_TABLE to RO_DATA segment

 arch/riscv/Kconfig                  | 1 +
 arch/riscv/kernel/vmlinux-xip.lds.S | 1 -
 arch/riscv/kernel/vmlinux.lds.S     | 4 ++--
 scripts/sorttable.c                 | 1 +
 4 files changed, 4 insertions(+), 3 deletions(-)

-- 
2.32.0

[PATCH v2 1/2] riscv: Enable BUILDTIME_TABLE_SORT

[Jisheng Zhang]

From: Jisheng Zhang <jszhang@kernel.org>

Enable BUILDTIME_TABLE_SORT to sort the exception table at build time
rather than during boot.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/riscv/Kconfig  | 1 +
 scripts/sorttable.c | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 80a7aa9f74de..570689d3889b 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -40,6 +40,7 @@ config RISCV
 	select ARCH_WANT_FRAME_POINTERS
 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
 	select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
+	select BUILDTIME_TABLE_SORT if MMU
 	select CLONE_BACKWARDS
 	select CLINT_TIMER if !MMU
 	select COMMON_CLK
diff --git a/scripts/sorttable.c b/scripts/sorttable.c
index 0ef3abfc4a51..f355869c65cd 100644
--- a/scripts/sorttable.c
+++ b/scripts/sorttable.c
@@ -349,6 +349,7 @@ static int do_file(char const *const fname, void *addr)
 	case EM_ARM:
 	case EM_MICROBLAZE:
 	case EM_MIPS:
+	case EM_RISCV:
 	case EM_XTENSA:
 		break;
 	default:
-- 
2.32.0

[PATCH v2 2/2] riscv: Move EXCEPTION_TABLE to RO_DATA segment

[Jisheng Zhang]

From: Jisheng Zhang <jszhang@kernel.org>

_ex_table section is read-only, so move it to RO_DATA.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 arch/riscv/kernel/vmlinux-xip.lds.S | 1 -
 arch/riscv/kernel/vmlinux.lds.S     | 4 ++--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/vmlinux-xip.lds.S b/arch/riscv/kernel/vmlinux-xip.lds.S
index af776555ded9..9c9f35091ef0 100644
--- a/arch/riscv/kernel/vmlinux-xip.lds.S
+++ b/arch/riscv/kernel/vmlinux-xip.lds.S
@@ -121,7 +121,6 @@ SECTIONS
 	}
 
 	BSS_SECTION(PAGE_SIZE, PAGE_SIZE, 0)
-	EXCEPTION_TABLE(0x10)
 
 	.rel.dyn : AT(ADDR(.rel.dyn) - LOAD_OFFSET) {
 		*(.rel.dyn*)
diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 502d0826ecb1..5104f3a871e3 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -4,6 +4,8 @@
  * Copyright (C) 2017 SiFive
  */
 
+#define RO_EXCEPTION_TABLE_ALIGN	16
+
 #ifdef CONFIG_XIP_KERNEL
 #include "vmlinux-xip.lds.S"
 #else
@@ -112,8 +114,6 @@ SECTIONS
 		*(.srodata*)
 	}
 
-	EXCEPTION_TABLE(0x10)
-
 	. = ALIGN(SECTION_ALIGN);
 	_data = .;
 
-- 
2.32.0

Re: [PATCH v2 0/2] riscv: improve __ex_table section handling

[Palmer Dabbelt]

On Thu, 26 Aug 2021 07:09:52 PDT (-0700), jszhang3@mail.ustc.edu.cn wrote:
> From: Jisheng Zhang <jszhang@kernel.org>
>
> Enable BUILDTIME_TABLE_SORT to sort the exception table at build time
> then move exception table to RO_DATA segment.
>
> Since v1:
>   - Only enable BUILDTIME_TABLE_SORT for MMU. Thank Palmer for catching
>     tinyconfig case.
>
> Jisheng Zhang (2):
>   riscv: Enable BUILDTIME_TABLE_SORT
>   riscv: Move EXCEPTION_TABLE to RO_DATA segment
>
>  arch/riscv/Kconfig                  | 1 +
>  arch/riscv/kernel/vmlinux-xip.lds.S | 1 -
>  arch/riscv/kernel/vmlinux.lds.S     | 4 ++--
>  scripts/sorttable.c                 | 1 +
>  4 files changed, 4 insertions(+), 3 deletions(-)

Thanks, this is on for-next.