From e16e65a02913d29a7b27c4e3a415ceec967b0629 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Sun, 29 Mar 2020 16:12:58 +0200 Subject: arm64: remove CONFIG_DEBUG_ALIGN_RODATA feature When CONFIG_DEBUG_ALIGN_RODATA is enabled, kernel segments mapped with different permissions (r-x for .text, r-- for .rodata, rw- for .data, etc) are rounded up to 2 MiB so they can be mapped more efficiently. In particular, it permits the segments to be mapped using level 2 block entries when using 4k pages, which is expected to result in less TLB pressure. However, the mappings for the bulk of the kernel will use level 2 entries anyway, and the misaligned fringes are organized such that they can take advantage of the contiguous bit, and use far fewer level 3 entries than would be needed otherwise. This makes the value of this feature dubious at best, and since it is not enabled in defconfig or in the distro configs, it does not appear to be in wide use either. So let's just remove it. Signed-off-by: Ard Biesheuvel Acked-by: Mark Rutland Acked-by: Will Deacon Acked-by: Laura Abbott Signed-off-by: Catalin Marinas --- arch/arm64/Kconfig.debug | 13 ------------- 1 file changed, 13 deletions(-) (limited to 'arch/arm64/Kconfig.debug') diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug index 1c906d932d6b..a1efa246c9ed 100644 --- a/arch/arm64/Kconfig.debug +++ b/arch/arm64/Kconfig.debug @@ -52,19 +52,6 @@ config DEBUG_WX If in doubt, say "Y". -config DEBUG_ALIGN_RODATA - depends on STRICT_KERNEL_RWX - 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. - - If in doubt, say N. - config DEBUG_EFI depends on EFI && DEBUG_INFO bool "UEFI debugging" -- cgit v1.2.3