From 58557e486f89823763039502923647037ef7032f Mon Sep 17 00:00:00 2001 From: Florian Fainelli Date: Mon, 17 Jun 2019 15:29:59 -0700 Subject: [PATCH] arm64: Allow user selection of ARM64_MODULE_PLTS Make ARM64_MODULE_PLTS a selectable Kconfig symbol, since some people might have very big modules spilling out of the dedicated module area into vmalloc. Help text is copied from the ARM 32-bit counterpart and modified to a mention of KASLR and specific ARM errata workaround(s). Acked-by: Will Deacon Signed-off-by: Florian Fainelli Signed-off-by: Catalin Marinas --- arch/arm64/Kconfig | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 57b02d4ceb71..22f8e6b3b0f9 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1418,8 +1418,23 @@ config ARM64_SVE KVM in the same kernel image. config ARM64_MODULE_PLTS - bool + bool "Use PLTs to allow module memory to spill over into vmalloc area" select HAVE_MOD_ARCH_SPECIFIC + help + Allocate PLTs when loading modules so that jumps and calls whose + targets are too far away for their relative offsets to be encoded + in the instructions themselves can be bounced via veneers in the + module's PLT. This allows modules to be allocated in the generic + vmalloc area after the dedicated module memory area has been + exhausted. + + When running with address space randomization (KASLR), the module + region itself may be too far away for ordinary relative jumps and + calls, and so in that case, module PLTs are required and cannot be + disabled. + + Specific errata workaround(s) might also force module PLTs to be + enabled (ARM64_ERRATUM_843419). config ARM64_PSEUDO_NMI bool "Support for NMI-like interrupts" -- 2.30.2