| Message ID | 27a078f43742063cc30e706b196fb5fff5d5c37e.1662459668.git.baskov@ispras.ru |
|---|---|
| State | Superseded |
| Headers | show |
| Series | x86_64: Improvements at compressed kernel stage | expand |
On Tue, 6 Sept 2022 at 12:41, 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. > > 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 = .; Why are you adding these? > *(.rodata..compressed) > + _ecompressed = .; > } > + . = ALIGN(PAGE_SIZE); On other EFI architectures, we only distinguish between R-X and RW- regions, and alignment between .rodata and .text is unnecessary. Do we really need to deviate from that here? > .text : { > _text = .; /* Text */ > *(.text) > *(.text.*) > _etext = . ; > } > + . = ALIGN(PAGE_SIZE); > .rodata : { > _rodata = . ; > *(.rodata) /* read-only data */ > *(.rodata.*) > _erodata = . ; > } > + . = ALIGN(PAGE_SIZE); > .data : { > _data = . ; > *(.data) > -- > 2.35.1 >
On 2022-10-19 10:01, Ard Biesheuvel wrote: > On Tue, 6 Sept 2022 at 12:41, 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. >> >> 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 = .; > > Why are you adding these? It is used for address compressed kernel blob during memory protection setup. Although it can be addressed via different symbols, I though that addressing sections data in a common way (through linker generated symbols) would be better. I can remove or mention the change in commit message (for now I will do the latter). > >> *(.rodata..compressed) >> + _ecompressed = .; >> } >> + . = ALIGN(PAGE_SIZE); > > On other EFI architectures, we only distinguish between R-X and RW- > regions, and alignment between .rodata and .text is unnecessary. Do we > really need to deviate from that here? I though that leaving a huge compressed kernel blob executable is undesirable, so I decided to split it out. I can make it either RW- or R-X if it would be more acceptable. > > >> .text : { >> _text = .; /* Text */ >> *(.text) >> *(.text.*) >> _etext = . ; >> } >> + . = ALIGN(PAGE_SIZE); >> .rodata : { >> _rodata = . ; >> *(.rodata) /* read-only data */ >> *(.rodata.*) >> _erodata = . ; >> } >> + . = ALIGN(PAGE_SIZE); >> .data : { >> _data = . ; >> *(.data) >> -- >> 2.35.1 >>
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)
To protect sections on page table level each section needs to be aligned on page size (4KB). Set sections alignment in linker script. Signed-off-by: Evgeniy Baskov <baskov@ispras.ru> --- arch/x86/boot/compressed/vmlinux.lds.S | 6 ++++++ 1 file changed, 6 insertions(+)