diff mbox series

[v4,1/3] target/riscv/kvm: add software breakpoints support

Message ID 20240606014501.20763-2-duchao@eswincomputing.com
State New
Headers show
Series target/riscv/kvm: QEMU support for KVM Guest Debug on RISC-V | expand

Commit Message

Chao Du June 6, 2024, 1:44 a.m. UTC 
This patch implements insert/remove software breakpoint process.

For RISC-V, GDB treats single-step similarly to breakpoint: add a
breakpoint at the next step address, then continue. So this also
works for single-step debugging.

Implement kvm_arch_update_guest_debug(): Set the control flag
when there are active breakpoints. This will help KVM to know
the status in the userspace.

Add some stubs which are necessary for building, and will be
implemented later.

Signed-off-by: Chao Du <duchao@eswincomputing.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
---
 target/riscv/kvm/kvm-cpu.c | 69 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
diff mbox series

Patch

diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index 235e2cdaca..748fe5980f 100644
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -1969,3 +1969,72 @@  static const TypeInfo riscv_kvm_cpu_type_infos[] = {
 };
 
 DEFINE_TYPES(riscv_kvm_cpu_type_infos)
+
+static const uint32_t ebreak_insn = 0x00100073;
+static const uint16_t c_ebreak_insn = 0x9002;
+
+int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
+{
+    if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 2, 0)) {
+        return -EINVAL;
+    }
+
+    if ((bp->saved_insn & 0x3) == 0x3) {
+        if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 0)
+            || cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&ebreak_insn, 4, 1)) {
+            return -EINVAL;
+        }
+    } else {
+        if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&c_ebreak_insn, 2, 1)) {
+            return -EINVAL;
+        }
+    }
+
+    return 0;
+}
+
+int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
+{
+    uint32_t ebreak;
+    uint16_t c_ebreak;
+
+    if ((bp->saved_insn & 0x3) == 0x3) {
+        if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&ebreak, 4, 0) ||
+            ebreak != ebreak_insn ||
+            cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 1)) {
+            return -EINVAL;
+        }
+    } else {
+        if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&c_ebreak, 2, 0) ||
+            c_ebreak != c_ebreak_insn ||
+            cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 2, 1)) {
+            return -EINVAL;
+        }
+    }
+
+    return 0;
+}
+
+int kvm_arch_insert_hw_breakpoint(vaddr addr, vaddr len, int type)
+{
+    /* TODO; To be implemented later. */
+    return -EINVAL;
+}
+
+int kvm_arch_remove_hw_breakpoint(vaddr addr, vaddr len, int type)
+{
+    /* TODO; To be implemented later. */
+    return -EINVAL;
+}
+
+void kvm_arch_remove_all_hw_breakpoints(void)
+{
+    /* TODO; To be implemented later. */
+}
+
+void kvm_arch_update_guest_debug(CPUState *cs, struct kvm_guest_debug *dbg)
+{
+    if (kvm_sw_breakpoints_active(cs)) {
+        dbg->control |= KVM_GUESTDBG_ENABLE;
+    }
+}