[PATCH v2 07/12] powerpc/32s: Allow disabling KUEP at boot time
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STALE1947d
LANDED
From: Christophe Leroy <hidden>
Date: 2021-06-03 08:41:55
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Linus Torvalds
Landed in mainline as 50d2f104cd95 on 2021-06-16.
PPC64 uses MMU features to enable/disable KUEP at boot time. But feature fixups are applied way too early on PPC32. Now that all KUEP related actions are in C following the conversion of KUEP initial setup and context switch in C, static branches can be used to enable/disable KUEP. Signed-off-by: Christophe Leroy <redacted> --- arch/powerpc/include/asm/book3s/32/kup.h | 6 +++++- arch/powerpc/mm/book3s32/kuep.c | 11 +++++++---- 2 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index 618ffc8e4ee9..2854d970dabe 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h@@ -7,6 +7,10 @@ #ifndef __ASSEMBLY__ +#include <linux/jump_label.h> + +extern struct static_key_false disable_kuep_key; + static __always_inline bool kuap_is_disabled(void) { return !IS_ENABLED(CONFIG_PPC_KUAP);
@@ -14,7 +18,7 @@ static __always_inline bool kuap_is_disabled(void) static __always_inline bool kuep_is_disabled(void) { - return !IS_ENABLED(CONFIG_PPC_KUEP); + return !IS_ENABLED(CONFIG_PPC_KUEP) || static_branch_unlikely(&disable_kuep_key); } static inline void kuep_lock(void)
diff --git a/arch/powerpc/mm/book3s32/kuep.c b/arch/powerpc/mm/book3s32/kuep.c
index 3147e2edcf63..3f6eb6e23fca 100644
--- a/arch/powerpc/mm/book3s32/kuep.c
+++ b/arch/powerpc/mm/book3s32/kuep.c@@ -3,15 +3,18 @@ #include <asm/kup.h> #include <asm/smp.h> +struct static_key_false disable_kuep_key; + void __init setup_kuep(bool disabled) { - kuep_lock(); + if (!disabled) + kuep_lock(); if (smp_processor_id() != boot_cpuid) return; - pr_info("Activating Kernel Userspace Execution Prevention\n"); - if (disabled) - pr_warn("KUEP cannot be disabled yet on 6xx when compiled in\n"); + static_branch_enable(&disable_kuep_key); + else + pr_info("Activating Kernel Userspace Execution Prevention\n"); }
--
2.25.0