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: 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>
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@ -67,7 +67,7 @@ test-kprobes-objs += kprobes-test-arm.o
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endif
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obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o
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obj-$(CONFIG_ARM_THUMBEE) += thumbee.o
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obj-$(CONFIG_KGDB) += kgdb.o
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obj-$(CONFIG_KGDB) += kgdb.o patch.o
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obj-$(CONFIG_ARM_UNWIND) += unwind.o
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obj-$(CONFIG_HAVE_TCM) += tcm.o
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obj-$(CONFIG_OF) += devtree.o
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@ -12,8 +12,12 @@
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#include <linux/irq.h>
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#include <linux/kdebug.h>
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#include <linux/kgdb.h>
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#include <linux/uaccess.h>
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#include <asm/traps.h>
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#include "patch.h"
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struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
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{
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{ "r0", 4, offsetof(struct pt_regs, ARM_r0)},
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@ -244,6 +248,31 @@ void kgdb_arch_exit(void)
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unregister_die_notifier(&kgdb_notifier);
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}
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int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
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{
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int err;
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/* patch_text() only supports int-sized breakpoints */
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BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);
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err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
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BREAK_INSTR_SIZE);
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if (err)
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return err;
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patch_text((void *)bpt->bpt_addr,
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*(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);
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return err;
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}
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int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
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{
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patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);
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return 0;
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}
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/*
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* Register our undef instruction hooks with ARM undef core.
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* We regsiter a hook specifically looking for the KGB break inst
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