1 files changed, 60 insertions, 0 deletions

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index db6720edfdd0..8bfb6146f753 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -43,6 +43,8 @@
 #include <linux/smp.h>
 #include <linux/nmi.h>
 #include <linux/hw_breakpoint.h>
+#include <linux/uaccess.h>
+#include <linux/memory.h>
 
 #include <asm/debugreg.h>
 #include <asm/apicdef.h>
@@ -741,6 +743,64 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
         regs->ip = ip;
 }
 
+int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
+{
+        int err;
+        char opc[BREAK_INSTR_SIZE];
+
+        bpt->type = BP_BREAKPOINT;
+        err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
+                                BREAK_INSTR_SIZE);
+        if (err)
+                return err;
+        err = probe_kernel_write((char *)bpt->bpt_addr,
+                                 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
+#ifdef CONFIG_DEBUG_RODATA
+        if (!err)
+                return err;
+        /*
+         * It is safe to call text_poke() because normal kernel execution
+         * is stopped on all cores, so long as the text_mutex is not locked.
+         */
+        if (mutex_is_locked(&text_mutex))
+                return -EBUSY;
+        text_poke((void *)bpt->bpt_addr, arch_kgdb_ops.gdb_bpt_instr,
+                  BREAK_INSTR_SIZE);
+        err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
+        if (err)
+                return err;
+        if (memcmp(opc, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE))
+                return -EINVAL;
+        bpt->type = BP_POKE_BREAKPOINT;
+#endif /* CONFIG_DEBUG_RODATA */
+        return err;
+}
+
+int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
+{
+#ifdef CONFIG_DEBUG_RODATA
+        int err;
+        char opc[BREAK_INSTR_SIZE];
+
+        if (bpt->type != BP_POKE_BREAKPOINT)
+                goto knl_write;
+        /*
+         * It is safe to call text_poke() because normal kernel execution
+         * is stopped on all cores, so long as the text_mutex is not locked.
+         */
+        if (mutex_is_locked(&text_mutex))
+                goto knl_write;
+        text_poke((void *)bpt->bpt_addr, bpt->saved_instr, BREAK_INSTR_SIZE);
+        err = probe_kernel_read(opc, (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
+        if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE))
+                goto knl_write;
+        return err;
+knl_write:
+#endif /* CONFIG_DEBUG_RODATA */
+        return probe_kernel_write((char *)bpt->bpt_addr,
+                                  (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
+}
+
 struct kgdb_arch arch_kgdb_ops = {
         /* Breakpoint instruction: */
         .gdb_bpt_instr          = { 0xcc },