| Message ID | 20230726173024.3684-4-jszhang@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | riscv: vdso.lds.S: some improvement | expand |
| Context | Check | Description |
|---|---|---|
| conchuod/cover_letter | success | Series has a cover letter |
| conchuod/tree_selection | success | Guessed tree name to be for-next at HEAD 471aba2e4760 |
| conchuod/fixes_present | success | Fixes tag not required for -next series |
| conchuod/maintainers_pattern | success | MAINTAINERS pattern errors before the patch: 4 and now 4 |
| conchuod/verify_signedoff | success | Signed-off-by tag matches author and committer |
| conchuod/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| conchuod/build_rv64_clang_allmodconfig | success | Errors and warnings before: 9 this patch: 9 |
| conchuod/module_param | success | Was 0 now: 0 |
| conchuod/build_rv64_gcc_allmodconfig | success | Errors and warnings before: 10 this patch: 10 |
| conchuod/build_rv32_defconfig | success | Build OK |
| conchuod/dtb_warn_rv64 | success | Errors and warnings before: 3 this patch: 3 |
| conchuod/header_inline | success | No static functions without inline keyword in header files |
| conchuod/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 33 lines checked |
| conchuod/build_rv64_nommu_k210_defconfig | success | Build OK |
| conchuod/verify_fixes | success | No Fixes tag |
| conchuod/build_rv64_nommu_virt_defconfig | success | Build OK |
On Thu, Jul 27, 2023 at 01:30:24AM +0800, Jisheng Zhang wrote: > I believe the hardcoded 0x800 and related comments come from the long > history VDSO_TEXT_OFFSET in x86 vdso code, but commit 5b9304933730 > ("x86 vDSO: generate vdso-syms.lds") and commit f6b46ebf904f ("x86 > vDSO: new layout") removes the comment and hard coding for x86. > > Similar as x86 and other arch, riscv doesn't need the rigid layout > using VDSO_TEXT_OFFSET since it "no longer matters to the kernel". > so we could remove the hard coding now, and removing it brings a > small vdso.so and aligns with other architectures. > > Also, having enough separation between data and text is important for > I-cache, so similar as x86, move .note, .eh_frame_hdr, and .eh_frame > between .rodata and .text. > > Signed-off-by: Jisheng Zhang <jszhang@kernel.org> > --- > arch/riscv/kernel/vdso/vdso.lds.S | 17 ++++++++--------- > 1 file changed, 8 insertions(+), 9 deletions(-) > > diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S > index 671aa21769bc..cbe2a179331d 100644 > --- a/arch/riscv/kernel/vdso/vdso.lds.S > +++ b/arch/riscv/kernel/vdso/vdso.lds.S > @@ -23,12 +23,8 @@ SECTIONS > .gnu.version_d : { *(.gnu.version_d) } > .gnu.version_r : { *(.gnu.version_r) } > > - .note : { *(.note.*) } :text :note > .dynamic : { *(.dynamic) } :text :dynamic > > - .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr > - .eh_frame : { KEEP (*(.eh_frame)) } :text > - > .rodata : { > *(.rodata .rodata.* .gnu.linkonce.r.*) > *(.got.plt) *(.got) > @@ -37,13 +33,16 @@ SECTIONS > *(.bss .bss.* .gnu.linkonce.b.*) > } > > + .note : { *(.note.*) } :text :note > + > + .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr > + .eh_frame : { KEEP (*(.eh_frame)) } :text > + > /* > - * This linker script is used both with -r and with -shared. > - * For the layouts to match, we need to skip more than enough > - * space for the dynamic symbol table, etc. If this amount is > - * insufficient, ld -shared will error; simply increase it here. > + * Text is well-separated from actual data: there's plenty of > + * stuff that isn't used at runtime in between. > */ > - . = 0x800; > + . = ALIGN(16); > .text : { *(.text .text.*) } :text > > . = ALIGN(4); > -- > 2.40.1 > Reviewed-by: Andrew Jones <ajones@ventanamicro.com> Thanks, drew
diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S index 671aa21769bc..cbe2a179331d 100644 --- a/arch/riscv/kernel/vdso/vdso.lds.S +++ b/arch/riscv/kernel/vdso/vdso.lds.S @@ -23,12 +23,8 @@ SECTIONS .gnu.version_d : { *(.gnu.version_d) } .gnu.version_r : { *(.gnu.version_r) } - .note : { *(.note.*) } :text :note .dynamic : { *(.dynamic) } :text :dynamic - .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr - .eh_frame : { KEEP (*(.eh_frame)) } :text - .rodata : { *(.rodata .rodata.* .gnu.linkonce.r.*) *(.got.plt) *(.got) @@ -37,13 +33,16 @@ SECTIONS *(.bss .bss.* .gnu.linkonce.b.*) } + .note : { *(.note.*) } :text :note + + .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr + .eh_frame : { KEEP (*(.eh_frame)) } :text + /* - * This linker script is used both with -r and with -shared. - * For the layouts to match, we need to skip more than enough - * space for the dynamic symbol table, etc. If this amount is - * insufficient, ld -shared will error; simply increase it here. + * Text is well-separated from actual data: there's plenty of + * stuff that isn't used at runtime in between. */ - . = 0x800; + . = ALIGN(16); .text : { *(.text .text.*) } :text . = ALIGN(4);
I believe the hardcoded 0x800 and related comments come from the long history VDSO_TEXT_OFFSET in x86 vdso code, but commit 5b9304933730 ("x86 vDSO: generate vdso-syms.lds") and commit f6b46ebf904f ("x86 vDSO: new layout") removes the comment and hard coding for x86. Similar as x86 and other arch, riscv doesn't need the rigid layout using VDSO_TEXT_OFFSET since it "no longer matters to the kernel". so we could remove the hard coding now, and removing it brings a small vdso.so and aligns with other architectures. Also, having enough separation between data and text is important for I-cache, so similar as x86, move .note, .eh_frame_hdr, and .eh_frame between .rodata and .text. Signed-off-by: Jisheng Zhang <jszhang@kernel.org> --- arch/riscv/kernel/vdso/vdso.lds.S | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-)