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arm: kgdb: Handle read-only text / modules

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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: Doug Anderson <dianders@chromium.org>
[kees: switched structure size check to BUILD_BUG_ON (sboyd)]
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
This commit is contained in:
Doug Anderson 2014-04-22 15:14:51 -07:00 committed by Kees Cook
parent 42d720d173
commit 23a4e4050b
2 changed files with 30 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

2
arch/arm/kernel/Makefile
View file

@ -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

29
arch/arm/kernel/kgdb.c
View file

@ -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