3 files changed, 62 insertions, 18 deletions

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index fdc37b3d0ce3..b9bd9d8de665 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>
@@ -742,6 +744,64 @@ 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 },
diff --git a/drivers/misc/kgdbts.c b/drivers/misc/kgdbts.c
index d087456ba089..3aa9a969b373 100644
--- a/drivers/misc/kgdbts.c
+++ b/drivers/misc/kgdbts.c
@@ -968,22 +968,6 @@ static void run_singlestep_break_test(void)
         kgdbts_break_test();
 }
 
-static void test_debug_rodata(void)
-{
-#ifdef CONFIG_DEBUG_RODATA
-        /* Until there is an api to write to read-only text segments, use
-         * HW breakpoints for the remainder of any tests, else print a
-         * failure message if hw breakpoints do not work.
-         */
-        if (!(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT && hwbreaks_ok)) {
-                eprintk("kgdbts: HW breakpoints BROKEN, ending tests\n");
-                return;
-        }
-        force_hwbrks = 1;
-        v1printk("kgdbts:Using HW breakpoints for SW breakpoint tests\n");
-#endif /* CONFIG_DEBUG_RODATA */
-}
-
 static void kgdbts_run_tests(void)
 {
         char *ptr;
@@ -1016,7 +1000,6 @@ static void kgdbts_run_tests(void)
                 v1printk("kgdbts:RUN access write breakpoint test\n");
                 run_hw_break_test(0);
         }
-        test_debug_rodata();
 
         /* required internal KGDB tests */
         v1printk("kgdbts:RUN plant and detach test\n");
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index e5d689c1d774..c4d2fc194ede 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -63,7 +63,8 @@ enum kgdb_bptype {
         BP_HARDWARE_BREAKPOINT,
         BP_WRITE_WATCHPOINT,
         BP_READ_WATCHPOINT,
-        BP_ACCESS_WATCHPOINT
+        BP_ACCESS_WATCHPOINT,
+        BP_POKE_BREAKPOINT,
 };
 
 enum kgdb_bpstate {