[PATCH v3 1/2] arm64: mm: Enable CONT_SIZE aligned sections for 64k page kernels.
From: Jeremy Linton <hidden>
Date: 2016-02-19 17:46:22
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
This change allows ALIGN_RODATA for 64k and 16k kernels. In the case of 64k/16k kernels it actually aligns to the CONT_SIZE (2M) rather than the SECTION_SIZE (which is 512M/32M). This makes it generally more useful, given contiguous hit enabled kernels. Reviewed-by: Ard Biesheuvel <redacted> Signed-off-by: Jeremy Linton <redacted> --- arch/arm64/Kconfig.debug | 13 +++++++------ arch/arm64/kernel/vmlinux.lds.S | 11 ++++++----- 2 files changed, 13 insertions(+), 11 deletions(-)
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug
index e13c4bf..9d33d5e 100644
--- a/arch/arm64/Kconfig.debug
+++ b/arch/arm64/Kconfig.debug@@ -59,15 +59,16 @@ 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 (2 MiB). 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 N
diff --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