| Message ID | 8211c633eb5dceeabee2996a4db91cd971cf7c77.1671098103.git.baskov@ispras.ru |
|---|---|
| State | New |
| Headers | show |
| Series | x86_64: Improvements at compressed kernel stage | expand |
On Thu, 15 Dec 2022 at 13:38, Evgeniy Baskov <baskov@ispras.ru> wrote: > > To protect sections on page table level each section > needs to be aligned on page size (4KB). > > Set sections alignment in linker script. > > Tested-by: Mario Limonciello <mario.limonciello@amd.com> > Tested-by: Peter Jones <pjones@redhat.com> > Signed-off-by: Evgeniy Baskov <baskov@ispras.ru> > --- > arch/x86/boot/compressed/vmlinux.lds.S | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S > index 112b2375d021..6be90f1a1198 100644 > --- a/arch/x86/boot/compressed/vmlinux.lds.S > +++ b/arch/x86/boot/compressed/vmlinux.lds.S > @@ -27,21 +27,27 @@ SECTIONS > HEAD_TEXT > _ehead = . ; > } > + . = ALIGN(PAGE_SIZE); > .rodata..compressed : { > + _compressed = .; > *(.rodata..compressed) Can you just move this bit into the rodata section below? > + _ecompressed = .; > } > + . = ALIGN(PAGE_SIZE); > .text : { Please use .text : ALIGN(PAGE_SIZE) { which marks the section as being page aligned, rather than just being placed on a 4k boundary. > _text = .; /* Text */ > *(.text) > *(.text.*) > _etext = . ; > } > + . = ALIGN(PAGE_SIZE); > .rodata : { > _rodata = . ; > *(.rodata) /* read-only data */ > *(.rodata.*) > _erodata = . ; > } > + . = ALIGN(PAGE_SIZE); > .data : { > _data = . ; > *(.data) > -- > 2.37.4 >
On 2023-03-10 17:43, Ard Biesheuvel wrote: > On Thu, 15 Dec 2022 at 13:38, Evgeniy Baskov <baskov@ispras.ru> wrote: >> >> To protect sections on page table level each section >> needs to be aligned on page size (4KB). >> >> Set sections alignment in linker script. >> >> Tested-by: Mario Limonciello <mario.limonciello@amd.com> >> Tested-by: Peter Jones <pjones@redhat.com> >> Signed-off-by: Evgeniy Baskov <baskov@ispras.ru> >> --- >> arch/x86/boot/compressed/vmlinux.lds.S | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/arch/x86/boot/compressed/vmlinux.lds.S >> b/arch/x86/boot/compressed/vmlinux.lds.S >> index 112b2375d021..6be90f1a1198 100644 >> --- a/arch/x86/boot/compressed/vmlinux.lds.S >> +++ b/arch/x86/boot/compressed/vmlinux.lds.S >> @@ -27,21 +27,27 @@ SECTIONS >> HEAD_TEXT >> _ehead = . ; >> } >> + . = ALIGN(PAGE_SIZE); >> .rodata..compressed : { >> + _compressed = .; >> *(.rodata..compressed) > > Can you just move this bit into the rodata section below? I don't think that easily possible, as the layout need to stay compatible with in-place extraction for non-UEFI boot. For that execution path the code in .head.text moves everything behind it to the end of the extraction buffer and extraction code overwrites compressed kernel blob progressively during extraction. And that is why we have effectively have two code sections... > >> + _ecompressed = .; >> } >> + . = ALIGN(PAGE_SIZE); >> .text : { > > Please use > > .text : ALIGN(PAGE_SIZE) { > > which marks the section as being page aligned, rather than just being > placed on a 4k boundary. Will fix in v5. > >> _text = .; /* Text */ >> *(.text) >> *(.text.*) >> _etext = . ; >> } >> + . = ALIGN(PAGE_SIZE); >> .rodata : { >> _rodata = . ; >> *(.rodata) /* read-only data */ >> *(.rodata.*) >> _erodata = . ; >> } >> + . = ALIGN(PAGE_SIZE); >> .data : { >> _data = . ; >> *(.data) >> -- >> 2.37.4 >>
On Sat, 11 Mar 2023 at 15:30, Evgeniy Baskov <baskov@ispras.ru> wrote: > > On 2023-03-10 17:43, Ard Biesheuvel wrote: > > On Thu, 15 Dec 2022 at 13:38, Evgeniy Baskov <baskov@ispras.ru> wrote: > >> > >> To protect sections on page table level each section > >> needs to be aligned on page size (4KB). > >> > >> Set sections alignment in linker script. > >> > >> Tested-by: Mario Limonciello <mario.limonciello@amd.com> > >> Tested-by: Peter Jones <pjones@redhat.com> > >> Signed-off-by: Evgeniy Baskov <baskov@ispras.ru> > >> --- > >> arch/x86/boot/compressed/vmlinux.lds.S | 6 ++++++ > >> 1 file changed, 6 insertions(+) > >> > >> diff --git a/arch/x86/boot/compressed/vmlinux.lds.S > >> b/arch/x86/boot/compressed/vmlinux.lds.S > >> index 112b2375d021..6be90f1a1198 100644 > >> --- a/arch/x86/boot/compressed/vmlinux.lds.S > >> +++ b/arch/x86/boot/compressed/vmlinux.lds.S > >> @@ -27,21 +27,27 @@ SECTIONS > >> HEAD_TEXT > >> _ehead = . ; > >> } > >> + . = ALIGN(PAGE_SIZE); > >> .rodata..compressed : { > >> + _compressed = .; > >> *(.rodata..compressed) > > > > Can you just move this bit into the rodata section below? > > I don't think that easily possible, as the layout need > to stay compatible with in-place extraction for non-UEFI boot. > For that execution path the code in .head.text moves everything > behind it to the end of the extraction buffer and extraction > code overwrites compressed kernel blob progressively during > extraction. And that is why we have effectively have two code > sections... > A right - thanks for explaining that to me. So in the end, I think it doesn't matter in any case if we just stick to a single .text section with R-X attributes and a single .data section with RW- attributes. > > > >> + _ecompressed = .; > >> } > >> + . = ALIGN(PAGE_SIZE); > >> .text : { > > > > Please use > > > > .text : ALIGN(PAGE_SIZE) { > > > > which marks the section as being page aligned, rather than just being > > placed on a 4k boundary. > > Will fix in v5. > > > > >> _text = .; /* Text */ > >> *(.text) > >> *(.text.*) > >> _etext = . ; > >> } > >> + . = ALIGN(PAGE_SIZE); > >> .rodata : { > >> _rodata = . ; > >> *(.rodata) /* read-only data */ > >> *(.rodata.*) > >> _erodata = . ; > >> } > >> + . = ALIGN(PAGE_SIZE); > >> .data : { > >> _data = . ; > >> *(.data) > >> -- > >> 2.37.4 > >>
diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S index 112b2375d021..6be90f1a1198 100644 --- a/arch/x86/boot/compressed/vmlinux.lds.S +++ b/arch/x86/boot/compressed/vmlinux.lds.S @@ -27,21 +27,27 @@ SECTIONS HEAD_TEXT _ehead = . ; } + . = ALIGN(PAGE_SIZE); .rodata..compressed : { + _compressed = .; *(.rodata..compressed) + _ecompressed = .; } + . = ALIGN(PAGE_SIZE); .text : { _text = .; /* Text */ *(.text) *(.text.*) _etext = . ; } + . = ALIGN(PAGE_SIZE); .rodata : { _rodata = . ; *(.rodata) /* read-only data */ *(.rodata.*) _erodata = . ; } + . = ALIGN(PAGE_SIZE); .data : { _data = . ; *(.data)