From: Jisheng Zhang <jszhang@kernel.org> To: Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu> Cc: Andrew Jones <ajones@ventanamicro.com>, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/3] riscv: vdso.lds.S: remove hardcoded 0x800 .text start addr Date: Thu, 27 Jul 2023 01:30:24 +0800 [thread overview] Message-ID: <20230726173024.3684-4-jszhang@kernel.org> (raw) In-Reply-To: <20230726173024.3684-1-jszhang@kernel.org> 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
WARNING: multiple messages have this Message-ID (diff)
From: Jisheng Zhang <jszhang@kernel.org> To: Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu> Cc: Andrew Jones <ajones@ventanamicro.com>, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/3] riscv: vdso.lds.S: remove hardcoded 0x800 .text start addr Date: Thu, 27 Jul 2023 01:30:24 +0800 [thread overview] Message-ID: <20230726173024.3684-4-jszhang@kernel.org> (raw) In-Reply-To: <20230726173024.3684-1-jszhang@kernel.org> 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 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2023-07-26 17:42 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-07-26 17:30 [PATCH 0/3] riscv: vdso.lds.S: some improvement Jisheng Zhang 2023-07-26 17:30 ` Jisheng Zhang 2023-07-26 17:30 ` [PATCH 1/3] riscv: vdso.lds.S: drop __alt_start and __alt_end symbols Jisheng Zhang 2023-07-26 17:30 ` Jisheng Zhang 2023-07-26 17:30 ` [PATCH 2/3] riscv: vdso.lds.S: merge .data section into .rodata section Jisheng Zhang 2023-07-26 17:30 ` Jisheng Zhang 2023-07-28 12:57 ` Andrew Jones 2023-07-28 12:57 ` Andrew Jones 2023-07-28 14:11 ` Jisheng Zhang 2023-07-28 14:11 ` Jisheng Zhang 2023-07-26 17:30 ` Jisheng Zhang [this message] 2023-07-26 17:30 ` [PATCH 3/3] riscv: vdso.lds.S: remove hardcoded 0x800 .text start addr Jisheng Zhang 2023-07-28 12:58 ` Andrew Jones 2023-07-28 12:58 ` Andrew Jones 2023-09-05 14:46 ` [PATCH 0/3] riscv: vdso.lds.S: some improvement Emil Renner Berthing 2023-09-05 14:46 ` Emil Renner Berthing
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