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Commit 6533b7c1 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc: Initial stack protector (-fstack-protector) support 



Partialy copied from commit c743f380 ("ARM: initial stack protector
(-fstack-protector) support")

This is the very basic stuff without the changing canary upon
task switch yet.  Just the Kconfig option and a constant canary
value initialized at boot time.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent d0563a12

arch/powerpc/Kconfig

+1 −0
Original line number Original line Diff line number Diff line
@@ -163,6 +163,7 @@ config PPC 
	select HAVE_VIRT_CPU_ACCOUNTING

	select HAVE_VIRT_CPU_ACCOUNTING

	select HAVE_ARCH_HARDENED_USERCOPY

	select HAVE_ARCH_HARDENED_USERCOPY

	select HAVE_KERNEL_GZIP

	select HAVE_KERNEL_GZIP

	select HAVE_CC_STACKPROTECTOR





config GENERIC_CSUM

config GENERIC_CSUM

	def_bool CPU_LITTLE_ENDIAN

	def_bool CPU_LITTLE_ENDIAN

arch/powerpc/include/asm/stackprotector.h

0 → 100644
+40 −0
Original line number Original line Diff line number Diff line 
/*

 * GCC stack protector support.

 *

 * Stack protector works by putting predefined pattern at the start of

 * the stack frame and verifying that it hasn't been overwritten when

 * returning from the function.  The pattern is called stack canary

 * and gcc expects it to be defined by a global variable called

 * "__stack_chk_guard" on PPC.  This unfortunately means that on SMP

 * we cannot have a different canary value per task.

 */



#ifndef _ASM_STACKPROTECTOR_H

#define _ASM_STACKPROTECTOR_H



#include <linux/random.h>

#include <linux/version.h>

#include <asm/reg.h>



extern unsigned long __stack_chk_guard;



/*

 * Initialize the stackprotector canary value.

 *

 * NOTE: this must only be called from functions that never return,

 * and it must always be inlined.

 */

static __always_inline void boot_init_stack_canary(void)

{

	unsigned long canary;



	/* Try to get a semi random initial value. */

	get_random_bytes(&canary, sizeof(canary));

	canary ^= mftb();

	canary ^= LINUX_VERSION_CODE;



	current->stack_canary = canary;

	__stack_chk_guard = current->stack_canary;

}



#endif	/* _ASM_STACKPROTECTOR_H */

arch/powerpc/kernel/Makefile

+4 −0
Original line number Original line Diff line number Diff line
@@ -19,6 +19,10 @@ CFLAGS_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) 
CFLAGS_btext.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)

CFLAGS_btext.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)

CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)

CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)





# -fstack-protector triggers protection checks in this code,

# but it is being used too early to link to meaningful stack_chk logic.

CFLAGS_prom_init.o += $(call cc-option, -fno-stack-protector)



ifdef CONFIG_FUNCTION_TRACER

ifdef CONFIG_FUNCTION_TRACER

# Do not trace early boot code

# Do not trace early boot code

CFLAGS_REMOVE_cputable.o = -mno-sched-epilog $(CC_FLAGS_FTRACE)

CFLAGS_REMOVE_cputable.o = -mno-sched-epilog $(CC_FLAGS_FTRACE)

arch/powerpc/kernel/process.c

+6 −0
Original line number Original line Diff line number Diff line
@@ -64,6 +64,12 @@ 
#include <linux/kprobes.h>

#include <linux/kprobes.h>

#include <linux/kdebug.h>

#include <linux/kdebug.h>





#ifdef CONFIG_CC_STACKPROTECTOR

#include <linux/stackprotector.h>

unsigned long __stack_chk_guard __read_mostly;

EXPORT_SYMBOL(__stack_chk_guard);

#endif



/* Transactional Memory debug */

/* Transactional Memory debug */

#ifdef TM_DEBUG_SW

#ifdef TM_DEBUG_SW

#define TM_DEBUG(x...) printk(KERN_INFO x)

#define TM_DEBUG(x...) printk(KERN_INFO x)