commit 80b605056d59bb5ee979e2e6ba60528fb3f9eb1b
author Chao Du <duchao@eswincomputing.com> Thu Jun 06 01:44:59 2024 +0000
committer Alistair Francis <alistair.francis@wdc.com> Wed Jun 26 22:45:14 2024 +1000
tree 2722b7dae35595044f034b8c61c21fb4f8ef9316
parent f42cdf2ea5b3a1dc369792d7acbf9cd3e5c90815

target/riscv/kvm: add software breakpoints support

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>
Message-ID: <20240606014501.20763-2-duchao@eswincomputing.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/kvm/kvm-cpu.c

diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index 235e2cd..748fe59 100644
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -1969,3 +1969,72 @@
 };
 
 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;
+    }
+}