[PATCH 1/2] target/xtensa: use generic instruction breakpoint infrastructure

[Max Filippov <jcmvbkbc@gmail.com>]

Don't embed ibreak exception generation into TB and don't invalidate TB
on ibreak address change. Add CPUBreakpoint pointers to xtensa
CPUArchState, use cpu_breakpoint_insert/cpu_breakpoint_remove_by_ref to
manage ibreak breakpoints and provide TCGCPUOps::debug_check_breakpoint
callback that recognizes valid instruction breakpoints.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 target/xtensa/cpu.c        |  1 +
 target/xtensa/cpu.h        |  4 ++++
 target/xtensa/dbg_helper.c | 46 +++++++++++++++++++++++++-------------
 target/xtensa/helper.c     | 12 ++++++++++
 target/xtensa/translate.c  | 17 --------------
 5 files changed, 47 insertions(+), 33 deletions(-)

diff --git a/target/xtensa/cpu.c b/target/xtensa/cpu.c
index e20fe87bf255..b74ee8917065 100644
--- a/target/xtensa/cpu.c
+++ b/target/xtensa/cpu.c
@@ -235,6 +235,7 @@ static const struct TCGCPUOps xtensa_tcg_ops = {
     .do_interrupt = xtensa_cpu_do_interrupt,
     .do_transaction_failed = xtensa_cpu_do_transaction_failed,
     .do_unaligned_access = xtensa_cpu_do_unaligned_access,
+    .debug_check_breakpoint = xtensa_debug_check_breakpoint,
 #endif /* !CONFIG_USER_ONLY */
 };
 
diff --git a/target/xtensa/cpu.h b/target/xtensa/cpu.h
index dd8172930653..8a423706d8c0 100644
--- a/target/xtensa/cpu.h
+++ b/target/xtensa/cpu.h
@@ -229,6 +229,7 @@ enum {
 #define MAX_NCCOMPARE 3
 #define MAX_TLB_WAY_SIZE 8
 #define MAX_NDBREAK 2
+#define MAX_NIBREAK 2
 #define MAX_NMEMORY 4
 #define MAX_MPU_FOREGROUND_SEGMENTS 32
 
@@ -547,6 +548,8 @@ struct CPUArchState {
 
     /* Watchpoints for DBREAK registers */
     struct CPUWatchpoint *cpu_watchpoint[MAX_NDBREAK];
+    /* Breakpoints for IBREAK registers */
+    struct CPUBreakpoint *cpu_breakpoint[MAX_NIBREAK];
 };
 
 /**
@@ -590,6 +593,7 @@ void xtensa_cpu_do_transaction_failed(CPUState *cs, hwaddr physaddr, vaddr addr,
                                       int mmu_idx, MemTxAttrs attrs,
                                       MemTxResult response, uintptr_t retaddr);
 hwaddr xtensa_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
+bool xtensa_debug_check_breakpoint(CPUState *cs);
 #endif
 void xtensa_cpu_dump_state(CPUState *cpu, FILE *f, int flags);
 void xtensa_count_regs(const XtensaConfig *config,
diff --git a/target/xtensa/dbg_helper.c b/target/xtensa/dbg_helper.c
index 3e0c9e8e8be0..497dafca719c 100644
--- a/target/xtensa/dbg_helper.c
+++ b/target/xtensa/dbg_helper.c
@@ -33,27 +33,21 @@
 #include "exec/exec-all.h"
 #include "exec/address-spaces.h"
 
-static void tb_invalidate_virtual_addr(CPUXtensaState *env, uint32_t vaddr)
-{
-    uint32_t paddr;
-    uint32_t page_size;
-    unsigned access;
-    int ret = xtensa_get_physical_addr(env, false, vaddr, 2, 0,
-                                       &paddr, &page_size, &access);
-    if (ret == 0) {
-        tb_invalidate_phys_addr(&address_space_memory, paddr,
-                                MEMTXATTRS_UNSPECIFIED);
-    }
-}
-
 void HELPER(wsr_ibreakenable)(CPUXtensaState *env, uint32_t v)
 {
+    CPUState *cs = env_cpu(env);
     uint32_t change = v ^ env->sregs[IBREAKENABLE];
     unsigned i;
 
     for (i = 0; i < env->config->nibreak; ++i) {
         if (change & (1 << i)) {
-            tb_invalidate_virtual_addr(env, env->sregs[IBREAKA + i]);
+            if (v & (1 << i)) {
+                cpu_breakpoint_insert(cs, env->sregs[IBREAKA + i],
+                                      BP_CPU, &env->cpu_breakpoint[i]);
+            } else {
+                cpu_breakpoint_remove_by_ref(cs, env->cpu_breakpoint[i]);
+                env->cpu_breakpoint[i] = NULL;
+            }
         }
     }
     env->sregs[IBREAKENABLE] = v & ((1 << env->config->nibreak) - 1);
@@ -62,12 +56,32 @@ void HELPER(wsr_ibreakenable)(CPUXtensaState *env, uint32_t v)
 void HELPER(wsr_ibreaka)(CPUXtensaState *env, uint32_t i, uint32_t v)
 {
     if (env->sregs[IBREAKENABLE] & (1 << i) && env->sregs[IBREAKA + i] != v) {
-        tb_invalidate_virtual_addr(env, env->sregs[IBREAKA + i]);
-        tb_invalidate_virtual_addr(env, v);
+        CPUState *cs = env_cpu(env);
+
+        cpu_breakpoint_remove_by_ref(cs, env->cpu_breakpoint[i]);
+        cpu_breakpoint_insert(cs, v, BP_CPU, &env->cpu_breakpoint[i]);
     }
     env->sregs[IBREAKA + i] = v;
 }
 
+bool xtensa_debug_check_breakpoint(CPUState *cs)
+{
+    XtensaCPU *cpu = XTENSA_CPU(cs);
+    CPUXtensaState *env = &cpu->env;
+    unsigned int i;
+
+    if (xtensa_get_cintlevel(env) >= env->config->debug_level) {
+        return false;
+    }
+    for (i = 0; i < env->config->nibreak; ++i) {
+        if (env->sregs[IBREAKENABLE] & (1 << i) &&
+            env->sregs[IBREAKA + i] == env->pc) {
+            return true;
+        }
+    }
+    return false;
+}
+
 static void set_dbreak(CPUXtensaState *env, unsigned i, uint32_t dbreaka,
         uint32_t dbreakc)
 {
diff --git a/target/xtensa/helper.c b/target/xtensa/helper.c
index dbeb97a953cc..151da75a41c5 100644
--- a/target/xtensa/helper.c
+++ b/target/xtensa/helper.c
@@ -231,6 +231,18 @@ void xtensa_breakpoint_handler(CPUState *cs)
             }
             cpu_loop_exit_noexc(cs);
         }
+    } else {
+        if (cpu_breakpoint_test(cs, env->pc, BP_GDB)
+            || !cpu_breakpoint_test(cs, env->pc, BP_CPU)) {
+            return;
+        }
+        if (env->sregs[ICOUNT] == 0xffffffff &&
+            xtensa_get_cintlevel(env) < env->sregs[ICOUNTLEVEL]) {
+            debug_exception_env(env, DEBUGCAUSE_IC);
+        } else {
+            debug_exception_env(env, DEBUGCAUSE_IB);
+        }
+        cpu_loop_exit_noexc(cs);
     }
 }
 
diff --git a/target/xtensa/translate.c b/target/xtensa/translate.c
index de899405994e..87947236ca3a 100644
--- a/target/xtensa/translate.c
+++ b/target/xtensa/translate.c
@@ -1123,19 +1123,6 @@ static inline unsigned xtensa_insn_len(CPUXtensaState *env, DisasContext *dc)
     return xtensa_op0_insn_len(dc, b0);
 }
 
-static void gen_ibreak_check(CPUXtensaState *env, DisasContext *dc)
-{
-    unsigned i;
-
-    for (i = 0; i < dc->config->nibreak; ++i) {
-        if ((env->sregs[IBREAKENABLE] & (1 << i)) &&
-                env->sregs[IBREAKA + i] == dc->pc) {
-            gen_debug_exception(dc, DEBUGCAUSE_IB);
-            break;
-        }
-    }
-}
-
 static void xtensa_tr_init_disas_context(DisasContextBase *dcbase,
                                          CPUState *cpu)
 {
@@ -1205,10 +1192,6 @@ static void xtensa_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)
         gen_set_label(label);
     }
 
-    if (dc->debug) {
-        gen_ibreak_check(env, dc);
-    }
-
     disas_xtensa_insn(env, dc);
 
     if (dc->icount) {
-- 
2.39.2