[Qemu-devel] [PATCH 12/13] Introduce BP_CPU as a breakpoint type

[Jan Kiszka <jan.kiszka@siemens.com>]

Add another breakpoint/watchpoint type to BP_GDB: BP_CPU. This type is
intended for hardware-assisted break/watchpoint emulations like the x86
architecture requires.

To keep the highest priority for BP_GDB breakpoints, this type is
always inserted at the head of break/watchpoint lists, thus is found
first when looking up the origin of a debug interruption.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 cpu-all.h |    1 +
 exec.c    |   46 ++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 39 insertions(+), 8 deletions(-)

Index: b/cpu-all.h
===================================================================
--- a/cpu-all.h
+++ b/cpu-all.h
@@ -806,6 +806,7 @@ void cpu_reset_interrupt(CPUState *env,
 #define BP_STOP_BEFORE_ACCESS 0x04
 #define BP_WATCHPOINT_HIT     0x08
 #define BP_GDB                0x10
+#define BP_CPU                0x20
 
 int cpu_breakpoint_insert(CPUState *env, target_ulong pc, int flags,
                           CPUBreakpoint **breakpoint);
Index: b/exec.c
===================================================================
--- a/exec.c
+++ b/exec.c
@@ -1236,7 +1236,7 @@ int cpu_watchpoint_insert(CPUState *env,
                           int flags, CPUWatchpoint **watchpoint)
 {
     target_ulong len_mask = ~(len - 1);
-    CPUWatchpoint *wp;
+    CPUWatchpoint *wp, *prev_wp;
 
     /* sanity checks: allow power-of-2 lengths, deny unaligned watchpoints */
     if ((len != 1 && len != 2 && len != 4) || (addr & ~len_mask))
@@ -1250,11 +1250,26 @@ int cpu_watchpoint_insert(CPUState *env,
     wp->len_mask = len_mask;
     wp->flags = flags;
 
-    wp->next = env->watchpoints;
-    wp->prev = NULL;
+    /* keep all GDB-injected watchpoints in front */
+    if (!(flags & BP_GDB) && env->watchpoints) {
+        prev_wp = env->watchpoints;
+        while (prev_wp->next != NULL && (prev_wp->next->flags & BP_GDB))
+            prev_wp = prev_wp->next;
+    } else {
+        prev_wp = NULL;
+    }
+
+    /* Insert new watchpoint */
+    if (prev_wp) {
+        wp->next = prev_wp->next;
+        prev_wp->next = wp;
+    } else {
+        wp->next = env->watchpoints;
+        env->watchpoints = wp;
+    }
     if (wp->next)
         wp->next->prev = wp;
-    env->watchpoints = wp;
+    wp->prev = prev_wp;
 
     tlb_flush_page(env, addr);
 
@@ -1310,7 +1325,7 @@ int cpu_breakpoint_insert(CPUState *env,
                           CPUBreakpoint **breakpoint)
 {
 #if defined(TARGET_HAS_ICE)
-    CPUBreakpoint *bp;
+    CPUBreakpoint *bp, *prev_bp;
 
     bp = qemu_malloc(sizeof(*bp));
     if (!bp)
@@ -1319,11 +1334,26 @@ int cpu_breakpoint_insert(CPUState *env,
     bp->pc = pc;
     bp->flags = flags;
 
-    bp->next = env->breakpoints;
-    bp->prev = NULL;
+    /* keep all GDB-injected breakpoints in front */
+    if (!(flags & BP_GDB) && env->breakpoints) {
+        prev_bp = env->breakpoints;
+        while (prev_bp->next != NULL && (prev_bp->next->flags & BP_GDB))
+            prev_bp = prev_bp->next;
+    } else {
+        prev_bp = NULL;
+    }
+
+    /* Insert new breakpoint */
+    if (prev_bp) {
+        bp->next = prev_bp->next;
+        prev_bp->next = bp;
+    } else {
+        bp->next = env->breakpoints;
+        env->breakpoints = bp;
+    }
     if (bp->next)
         bp->next->prev = bp;
-    env->breakpoints = bp;
+    bp->prev = prev_bp;
 
     breakpoint_invalidate(env, pc);