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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2016-10-17 16:18:39 +0100
committerWill Deacon <will.deacon@arm.com>2016-10-17 16:24:02 +0100
commit8fe88a4145cdeee486af60e61f5d5a14f804fa45 (patch)
tree59d398ebc747e7c1f13d896ee47e0ded25ce048a /arch/arm64/Kconfig
parentarm64: kernel: Init MDCR_EL2 even in the absence of a PMU (diff)
downloadlinux-dev-8fe88a4145cdeee486af60e61f5d5a14f804fa45.tar.xz
linux-dev-8fe88a4145cdeee486af60e61f5d5a14f804fa45.zip
arm64: kaslr: keep modules close to the kernel when DYNAMIC_FTRACE=y
The RANDOMIZE_MODULE_REGION_FULL Kconfig option allows KASLR to be configured in such a way that kernel modules and the core kernel are allocated completely independently, which implies that modules are likely to require branches via PLT entries to reach the core kernel. The dynamic ftrace code does not expect that, and assumes that it can patch module code to perform a relative branch to anywhere in the core kernel. This may result in errors such as branch_imm_common: offset out of range ------------[ cut here ]------------ WARNING: CPU: 3 PID: 196 at kernel/trace/ftrace.c:1995 ftrace_bug+0x220/0x2e8 Modules linked in: CPU: 3 PID: 196 Comm: systemd-udevd Not tainted 4.8.0-22-generic #24 Hardware name: AMD Seattle/Seattle, BIOS 10:34:40 Oct 6 2016 task: ffff8d1bef7dde80 task.stack: ffff8d1bef6b0000 PC is at ftrace_bug+0x220/0x2e8 LR is at ftrace_process_locs+0x330/0x430 So make RANDOMIZE_MODULE_REGION_FULL mutually exclusive with DYNAMIC_FTRACE at the Kconfig level. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/Kconfig')
-rw-r--r--arch/arm64/Kconfig2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 30398dbc940a..969ef880d234 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -915,7 +915,7 @@ 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 && !DYNAMIC_FTRACE
default y
help
Randomizes the location of the module region without considering the