[PATCH v5 2/2] powerpc/64: add stack protector support
From: Christophe Leroy <hidden>
Date: 2018-09-27 07:06:01
Also in:
lkml
Subsystem:
linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
On PPC64, as register r13 points to the paca_struct at all time, this patch adds a copy of the canary there, which is copied at task_switch. That new canary is then used by using the following GCC options: -mstack-protector-guard=tls -mstack-protector-guard-reg=r13 -mstack-protector-guard-offset=offsetof(struct paca_struct, canary)) Signed-off-by: Christophe Leroy <redacted> --- arch/powerpc/Kconfig | 2 +- arch/powerpc/Makefile | 8 ++++++++ arch/powerpc/include/asm/paca.h | 3 +++ arch/powerpc/include/asm/stackprotector.h | 4 ++++ arch/powerpc/kernel/asm-offsets.c | 3 +++ arch/powerpc/kernel/entry_64.S | 4 ++++ 6 files changed, 23 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3bcb05929931..602eea723624 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig@@ -180,7 +180,7 @@ config PPC select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_TRACEHOOK select HAVE_CBPF_JIT if !PPC64 - select HAVE_STACKPROTECTOR if $(cc-option,-mstack-protector-guard=tls) && PPC32 + select HAVE_STACKPROTECTOR if $(cc-option,-mstack-protector-guard=tls) select HAVE_CONTEXT_TRACKING if PPC64 select HAVE_DEBUG_KMEMLEAK select HAVE_DEBUG_STACKOVERFLOW
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 45b8eb4d8fe7..81552c7b46eb 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile@@ -113,7 +113,11 @@ KBUILD_ARFLAGS += --target=elf$(BITS)-$(GNUTARGET) endif cflags-$(CONFIG_STACKPROTECTOR) += -mstack-protector-guard=tls +ifdef CONFIG_PPC64 +cflags-$(CONFIG_STACKPROTECTOR) += -mstack-protector-guard-reg=r13 +else cflags-$(CONFIG_STACKPROTECTOR) += -mstack-protector-guard-reg=r2 +endif LDFLAGS_vmlinux-y := -Bstatic LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
@@ -411,8 +415,12 @@ ifdef CONFIG_STACKPROTECTOR prepare: stack_protector_prepare stack_protector_prepare: prepare0 +ifdef CONFIG_PPC64 + $(eval KBUILD_CFLAGS += -mstack-protector-guard-offset=$(shell awk '{if ($$2 == "PACA_CANARY") print $$3;}' include/generated/asm-offsets.h)) +else $(eval KBUILD_CFLAGS += -mstack-protector-guard-offset=$(shell awk '{if ($$2 == "TASK_CANARY") print $$3;}' include/generated/asm-offsets.h)) endif +endif # Use the file '.tmp_gas_check' for binutils tests, as gas won't output # to stdout and these checks are run even on install targets.
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index 6d6b3706232c..98d883e58945 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h@@ -246,6 +246,9 @@ struct paca_struct { struct slb_entry *mce_faulty_slbs; u16 slb_save_cache_ptr; #endif /* CONFIG_PPC_BOOK3S_64 */ +#ifdef CONFIG_STACKPROTECTOR + unsigned long canary; +#endif } ____cacheline_aligned; extern struct paca_struct **paca_ptrs;
diff --git a/arch/powerpc/include/asm/stackprotector.h b/arch/powerpc/include/asm/stackprotector.h
index d05d969c98c2..1c8460e23583 100644
--- a/arch/powerpc/include/asm/stackprotector.h
+++ b/arch/powerpc/include/asm/stackprotector.h@@ -11,6 +11,7 @@ #include <linux/version.h> #include <asm/reg.h> #include <asm/current.h> +#include <asm/paca.h> /* * Initialize the stackprotector canary value.
@@ -29,6 +30,9 @@ static __always_inline void boot_init_stack_canary(void) canary &= CANARY_MASK; current->stack_canary = canary; +#ifdef CONFIG_PPC64 + get_paca()->canary = canary; +#endif } #endif /* _ASM_STACKPROTECTOR_H */
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index a992f7a53cf3..773dee55b3f6 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c@@ -81,6 +81,9 @@ int main(void) OFFSET(MM, task_struct, mm); #ifdef CONFIG_STACKPROTECTOR OFFSET(TASK_CANARY, task_struct, stack_canary); +#ifdef CONFIG_PPC64 + OFFSET(PACA_CANARY, paca_struct, canary); +#endif #endif OFFSET(MMCONTEXTID, mm_struct, context.id); #ifdef CONFIG_PPC64
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 77a888bfcb53..573fa879d785 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S@@ -624,6 +624,10 @@ _GLOBAL(_switch) addi r6,r4,-THREAD /* Convert THREAD to 'current' */ std r6,PACACURRENT(r13) /* Set new 'current' */ +#if defined(CONFIG_STACKPROTECTOR) + ld r6, TASK_CANARY(r6) + std r6, PACA_CANARY(r13) +#endif ld r8,KSP(r4) /* new stack pointer */ #ifdef CONFIG_PPC_BOOK3S_64
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2.13.3