[PATCH 13/15] arm64: add a workaround for GNU gold with ARM64_MODULE_PLTS
From: Ard Biesheuvel <hidden>
Date: 2017-11-03 20:09:44
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On 3 November 2017 at 17:12, Sami Tolvanen [off-list ref] wrote:
CONFIG_CLANG_LTO depends on GNU gold and due to a known bug, the linker crashes when ARM64_MODULE_PLTS is enabled: https://sourceware.org/bugzilla/show_bug.cgi?id=14592 To work around the problem, this change: 1) Enables ARM64_MODULE_PLTS only when it's needed, i.e. when RANDOMIZE_MODULE_REGION_FULL is selected,
This is not true. Even when RANDOMIZE_MODULE_REGION_FULL is not enabled, we may need module PLTs. When the module region is randomized, it shares its chunk of vmalloc space with other users, and so there is a [low] probability that the module region we choose is used up by vmalloc/vmap/ioremap allocations, and so we need to be able to fall back to the general vmalloc space.
quoted hunk ↗ jump to hunk
2) and disables RANDOMIZE_MODULE_REGION_FULL with clang LTO. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- arch/arm64/Kconfig | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 43ccddb7c8ec..a301fdc90319 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig@@ -997,8 +997,8 @@ config RELOCATABLE config RANDOMIZE_BASE bool "Randomize the address of the kernel image" - select ARM64_MODULE_PLTS if MODULES select RELOCATABLE + select ARM64_MODULE_PLTS if RANDOMIZE_MODULE_REGION_FULL help Randomizes the virtual address at which the kernel image is loaded, as a security feature that deters exploit attempts@@ -1016,7 +1016,7 @@ config RANDOMIZE_BASE config RANDOMIZE_MODULE_REGION_FULL bool "Randomize the module region independently from the core kernel" - depends on RANDOMIZE_BASE + depends on RANDOMIZE_BASE && !CLANG_LTO default y help Randomizes the location of the module region without considering the --2.15.0.403.gc27cc4dac6-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel at lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel