[PATCH v2 1/2] arm64: mm: Enable CONT_SIZE aligned sections for 64k page kernels.
From: Ard Biesheuvel <hidden>
Date: 2016-02-17 17:17:46
On 17 February 2016 at 17:29, Jeremy Linton [off-list ref] wrote:
This change allows ALIGN_RODATA for 16k and 64k kernels. In the case of 64k kernels it actually aligns to the CONT_SIZE
... and 16k kernels ...
rather than the SECTION_SIZE (which is 512M). This makes it generally more useful, especially for CONT enabled kernels. Signed-off-by: Jeremy Linton <redacted>
It probably makes sense to mention here that the alignment is 2 MB for all page sizes. Reviewed-by: Ard Biesheuvel <redacted>
quoted hunk ↗ jump to hunk
--- arch/arm64/Kconfig.debug | 12 ++++++------ arch/arm64/kernel/vmlinux.lds.S | 11 ++++++----- 2 files changed, 12 insertions(+), 11 deletions(-)diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug index e13c4bf..65705ee 100644 --- a/arch/arm64/Kconfig.debug +++ b/arch/arm64/Kconfig.debug@@ -59,15 +59,15 @@ config DEBUG_RODATA If in doubt, say Y config DEBUG_ALIGN_RODATA - depends on DEBUG_RODATA && ARM64_4K_PAGES + depends on DEBUG_RODATA bool "Align linker sections up to SECTION_SIZE" help If this option is enabled, sections that may potentially be marked as - read only or non-executable will be aligned up to the section size of - the kernel. This prevents sections from being split into pages and - avoids a potential TLB penalty. The downside is an increase in - alignment and potentially wasted space. Turn on this option if - performance is more important than memory pressure. + read only or non-executable will be aligned up to the section size + or contiguous hint size of the kernel. This prevents sections from + being split into pages and avoids a potential TLB penalty. The downside + is an increase in alignment and potentially wasted space. Turn on + this option if performance is more important than memory pressure. If in doubt, say Ndiff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index b78a3c7..8f4fc2c 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S@@ -63,13 +63,14 @@ PECOFF_FILE_ALIGNMENT = 0x200; #endif #if defined(CONFIG_DEBUG_ALIGN_RODATA) -#define ALIGN_DEBUG_RO . = ALIGN(1<<SECTION_SHIFT); -#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO +#if defined(CONFIG_ARM64_4K_PAGES) +#define ALIGN_DEBUG_RO_MIN(min) . = ALIGN(SECTION_SIZE); +#else +#define ALIGN_DEBUG_RO_MIN(min) . = ALIGN(CONT_SIZE); +#endif #elif defined(CONFIG_DEBUG_RODATA) -#define ALIGN_DEBUG_RO . = ALIGN(1<<PAGE_SHIFT); -#define ALIGN_DEBUG_RO_MIN(min) ALIGN_DEBUG_RO +#define ALIGN_DEBUG_RO_MIN(min) . = ALIGN(PAGE_SIZE); #else -#define ALIGN_DEBUG_RO #define ALIGN_DEBUG_RO_MIN(min) . = ALIGN(min); #endif --2.4.3