Commit 06ec27ae authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/64: add stack protector support 



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: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent c3ff2a51

arch/powerpc/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -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

arch/powerpc/Makefile

+8 −0
Original line number Diff line number Diff line
@@ -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.

arch/powerpc/include/asm/paca.h

+3 −0
Original line number Diff line number Diff line
@@ -256,6 +256,9 @@ 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 void copy_mm_to_paca(struct mm_struct *mm);

arch/powerpc/include/asm/stackprotector.h

+4 −0
Original line number Diff line number Diff line
@@ -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 */

arch/powerpc/kernel/asm-offsets.c

+3 −0
Original line number Diff line number Diff line
@@ -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

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