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Commit 40d1a07b authored by Max Filippov's avatar Max Filippov
Browse files

xtensa: enable stack protector 



The implementation is adopted from the ARM arch. GCC 7.3, 8 or newer is
required for building the xtensa kernel with SSP.

Signed-off-by: default avatarMax Filippov <jcmvbkbc@gmail.com>
parent aa6476f7

Documentation/features/debug/stackprotector/arch-support.txt

+1 −1
Original line number Diff line number Diff line
@@ -35,5 +35,5 @@ 
    |          um: | TODO |

    |   unicore32: | TODO |

    |         x86: |  ok  |

    |      xtensa: | TODO |

    |      xtensa: |  ok  |

    -----------------------

arch/xtensa/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ config XTENSA 
	select GENERIC_IRQ_SHOW

	select GENERIC_PCI_IOMAP

	select GENERIC_SCHED_CLOCK

	select HAVE_CC_STACKPROTECTOR

	select HAVE_DEBUG_KMEMLEAK

	select HAVE_DMA_API_DEBUG

	select HAVE_DMA_CONTIGUOUS

arch/xtensa/boot/lib/Makefile

+4 −0
Original line number Diff line number Diff line
@@ -15,6 +15,10 @@ CFLAGS_REMOVE_inftrees.o = -pg 
CFLAGS_REMOVE_inffast.o = -pg

endif



CFLAGS_REMOVE_inflate.o += -fstack-protector -fstack-protector-strong

CFLAGS_REMOVE_zmem.o += -fstack-protector -fstack-protector-strong

CFLAGS_REMOVE_inftrees.o += -fstack-protector -fstack-protector-strong

CFLAGS_REMOVE_inffast.o += -fstack-protector -fstack-protector-strong



quiet_cmd_copy_zlib = COPY    $@

      cmd_copy_zlib = cat $< > $@

arch/xtensa/include/asm/stackprotector.h

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

 * GCC stack protector support.

 *

 * (This is directly adopted from the ARM implementation)

 *

 * 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 Xtensa.  This unfortunately means that on SMP

 * we cannot have a different canary value per task.

 */



#ifndef _ASM_STACKPROTECTOR_H

#define _ASM_STACKPROTECTOR_H 1



#include <linux/random.h>

#include <linux/version.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 ^= LINUX_VERSION_CODE;



	current->stack_canary = canary;

	__stack_chk_guard = current->stack_canary;

}



#endif	/* _ASM_STACKPROTECTOR_H */

arch/xtensa/kernel/asm-offsets.c

+3 −0
Original line number Diff line number Diff line
@@ -76,6 +76,9 @@ int main(void) 
	DEFINE(TASK_PID, offsetof (struct task_struct, pid));

	DEFINE(TASK_THREAD, offsetof (struct task_struct, thread));

	DEFINE(TASK_THREAD_INFO, offsetof (struct task_struct, stack));

#ifdef CONFIG_CC_STACKPROTECTOR

	DEFINE(TASK_STACK_CANARY, offsetof(struct task_struct, stack_canary));

#endif

	DEFINE(TASK_STRUCT_SIZE, sizeof (struct task_struct));



	/* offsets in thread_info struct */