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Commit 23a4e405 authored by Doug Anderson's avatar Doug Anderson Committed by Kees Cook
Browse files

arm: kgdb: Handle read-only text / modules 



Handle the case where someone has set the text segment of the kernel
as read-only by using the newly introduced "patch" mechanism.

Signed-off-by: default avatarDoug Anderson <dianders@chromium.org>
[kees: switched structure size check to BUILD_BUG_ON (sboyd)]
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarNicolas Pitre <nico@linaro.org>
parent 42d720d1

arch/arm/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ test-kprobes-objs += kprobes-test-arm.o 
endif

obj-$(CONFIG_OABI_COMPAT)	+= sys_oabi-compat.o

obj-$(CONFIG_ARM_THUMBEE)	+= thumbee.o

obj-$(CONFIG_KGDB)		+= kgdb.o

obj-$(CONFIG_KGDB)		+= kgdb.o patch.o

obj-$(CONFIG_ARM_UNWIND)	+= unwind.o

obj-$(CONFIG_HAVE_TCM)		+= tcm.o

obj-$(CONFIG_OF)		+= devtree.o

arch/arm/kernel/kgdb.c

+29 −0
Original line number Diff line number Diff line
@@ -12,8 +12,12 @@ 
#include <linux/irq.h>

#include <linux/kdebug.h>

#include <linux/kgdb.h>

#include <linux/uaccess.h>



#include <asm/traps.h>



#include "patch.h"



struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =

{

	{ "r0", 4, offsetof(struct pt_regs, ARM_r0)},
@@ -244,6 +248,31 @@ void kgdb_arch_exit(void) 
	unregister_die_notifier(&kgdb_notifier);

}



int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)

{

	int err;



	/* patch_text() only supports int-sized breakpoints */

	BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);



	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,

				BREAK_INSTR_SIZE);

	if (err)

		return err;



	patch_text((void *)bpt->bpt_addr,

		   *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);



	return err;

}



int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)

{

	patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);



	return 0;

}



/*

 * Register our undef instruction hooks with ARM undef core.

 * We regsiter a hook specifically looking for the KGB break inst