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Re: [PATCH v1 1/4] target/riscv/kvm: add software breakpoints support
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From: |
Andrew Jones |
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Subject: |
Re: [PATCH v1 1/4] target/riscv/kvm: add software breakpoints support |
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Date: |
Mon, 27 May 2024 17:41:10 +0200 |
On Mon, May 27, 2024 at 02:19:13AM GMT, Chao Du wrote:
> This patch implements insert/remove software breakpoint process:
>
> Add an input parameter for kvm_arch_insert_sw_breakpoint() and
> kvm_arch_remove_sw_breakpoint() to pass the length information,
> which helps us to know whether it is a RVC instruction.
> For some remove cases, we do not have the length info, so we need
> to judge by ourselves.
>
> 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.
>
> Add some stubs which are necessary for building, and will be
> implemented later.
>
> Signed-off-by: Chao Du <duchao@eswincomputing.com>
> ---
> accel/kvm/kvm-all.c | 8 ++--
> include/sysemu/kvm.h | 6 ++-
> target/arm/kvm.c | 6 ++-
> target/i386/kvm/kvm.c | 6 ++-
> target/mips/kvm.c | 6 ++-
> target/ppc/kvm.c | 6 ++-
> target/riscv/kvm/kvm-cpu.c | 79 ++++++++++++++++++++++++++++++++++++++
> target/s390x/kvm/kvm.c | 6 ++-
> 8 files changed, 107 insertions(+), 16 deletions(-)
>
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index c0be9f5eed..d27e77dbb2 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -3357,7 +3357,7 @@ int kvm_insert_breakpoint(CPUState *cpu, int type,
> vaddr addr, vaddr len)
> bp = g_new(struct kvm_sw_breakpoint, 1);
> bp->pc = addr;
> bp->use_count = 1;
> - err = kvm_arch_insert_sw_breakpoint(cpu, bp);
> + err = kvm_arch_insert_sw_breakpoint(cpu, bp, len);
> if (err) {
> g_free(bp);
> return err;
> @@ -3396,7 +3396,7 @@ int kvm_remove_breakpoint(CPUState *cpu, int type,
> vaddr addr, vaddr len)
> return 0;
> }
>
> - err = kvm_arch_remove_sw_breakpoint(cpu, bp);
> + err = kvm_arch_remove_sw_breakpoint(cpu, bp, len);
> if (err) {
> return err;
> }
> @@ -3426,10 +3426,10 @@ void kvm_remove_all_breakpoints(CPUState *cpu)
> CPUState *tmpcpu;
>
> QTAILQ_FOREACH_SAFE(bp, &s->kvm_sw_breakpoints, entry, next) {
> - if (kvm_arch_remove_sw_breakpoint(cpu, bp) != 0) {
> + if (kvm_arch_remove_sw_breakpoint(cpu, bp, 0) != 0) {
> /* Try harder to find a CPU that currently sees the breakpoint.
> */
> CPU_FOREACH(tmpcpu) {
> - if (kvm_arch_remove_sw_breakpoint(tmpcpu, bp) == 0) {
> + if (kvm_arch_remove_sw_breakpoint(tmpcpu, bp, 0) == 0) {
It's not nice to need to add 'len' to all arch insert/remove sw breakpoint
implementations, and the fact we have to pass zero sometimes implies it's
not the right approach.
> break;
> }
> }
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index c31d9c7356..340e094ffb 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -391,9 +391,11 @@ struct kvm_sw_breakpoint
> *kvm_find_sw_breakpoint(CPUState *cpu,
> int kvm_sw_breakpoints_active(CPUState *cpu);
>
> int kvm_arch_insert_sw_breakpoint(CPUState *cpu,
> - struct kvm_sw_breakpoint *bp);
> + struct kvm_sw_breakpoint *bp,
> + vaddr len);
> int kvm_arch_remove_sw_breakpoint(CPUState *cpu,
> - struct kvm_sw_breakpoint *bp);
> + struct kvm_sw_breakpoint *bp,
> + vaddr len);
> int kvm_arch_insert_hw_breakpoint(vaddr addr, vaddr len, int type);
> int kvm_arch_remove_hw_breakpoint(vaddr addr, vaddr len, int type);
> void kvm_arch_remove_all_hw_breakpoints(void);
> diff --git a/target/arm/kvm.c b/target/arm/kvm.c
> index 7cf5cf31de..84593db544 100644
> --- a/target/arm/kvm.c
> +++ b/target/arm/kvm.c
> @@ -2402,7 +2402,8 @@ void kvm_arch_on_sigbus_vcpu(CPUState *c, int code,
> void *addr)
> /* C6.6.29 BRK instruction */
> static const uint32_t brk_insn = 0xd4200000;
>
> -int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> {
> if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, 4, 0) ||
> cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&brk_insn, 4, 1)) {
> @@ -2411,7 +2412,8 @@ int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct
> kvm_sw_breakpoint *bp)
> return 0;
> }
>
> -int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> {
> static uint32_t brk;
>
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index c5943605ee..6449f796d0 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -4992,7 +4992,8 @@ static int kvm_handle_tpr_access(X86CPU *cpu)
> return 1;
> }
>
> -int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> {
> static const uint8_t int3 = 0xcc;
>
> @@ -5003,7 +5004,8 @@ int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct
> kvm_sw_breakpoint *bp)
> return 0;
> }
>
> -int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> {
> uint8_t int3;
>
> diff --git a/target/mips/kvm.c b/target/mips/kvm.c
> index a631ab544f..129964cf6d 100644
> --- a/target/mips/kvm.c
> +++ b/target/mips/kvm.c
> @@ -111,13 +111,15 @@ void kvm_mips_reset_vcpu(MIPSCPU *cpu)
> DPRINTF("%s\n", __func__);
> }
>
> -int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> {
> DPRINTF("%s\n", __func__);
> return 0;
> }
>
> -int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> {
> DPRINTF("%s\n", __func__);
> return 0;
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 46fccff786..9b76bdaa05 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -1378,7 +1378,8 @@ static int kvmppc_handle_dcr_write(CPUPPCState *env,
> return 0;
> }
>
> -int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> {
> /* Mixed endian case is not handled */
> uint32_t sc = debug_inst_opcode;
> @@ -1392,7 +1393,8 @@ int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct
> kvm_sw_breakpoint *bp)
> return 0;
> }
>
> -int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> {
> uint32_t sc;
>
> diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
> index 473416649f..cba55c552d 100644
> --- a/target/riscv/kvm/kvm-cpu.c
> +++ b/target/riscv/kvm/kvm-cpu.c
> @@ -1962,3 +1962,82 @@ 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,
> + vaddr len)
> +{
> + if (len != 4 && len != 2) {
> + return -EINVAL;
> + }
> +
> + uint8_t * insn = (len == 4) ? (uint8_t *)&ebreak_insn :
> + (uint8_t *)&c_ebreak_insn;
> +
> + if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn, len, 0)
> ||
> + cpu_memory_rw_debug(cs, bp->pc, insn, len, 1)) {
> + return -EINVAL;
> + }
We can also read 2 bytes. So how about
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, &ebreak_insn, 4, 1)) {
return -EINVAL;
}
} else {
if (cpu_memory_rw_debug(cs, bp->pc, &c_ebreak_insn, 2, 1)) {
return -EINVAL;
}
}
> +
> + return 0;
> +}
> +
> +int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> +{
> + uint8_t length;
> +
> + if (len == 4 || len == 2) {
> + length = (uint8_t)len;
> + } else if (len == 0) {
> + /* Need to decide the instruction length in this case. */
> + uint32_t read_4_bytes;
> + uint16_t read_2_bytes;
> +
> + if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&read_4_bytes, 4, 0)
> ||
> + cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&read_2_bytes, 2, 0))
> {
> + return -EINVAL;
> + }
> +
> + if (read_4_bytes == ebreak_insn) {
> + length = 4;
> + } else if (read_2_bytes == c_ebreak_insn) {
> + length = 2;
> + } else {
> + return -EINVAL;
> + }
> + } else {
> + return -EINVAL;
> + }
> +
> + if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&bp->saved_insn,
> + length, 1)) {
> + return -EINVAL;
> + }
Also no need need for 'len'.
uint16_t ebreak;
if (cpu_memory_rw_debug(cs, bp->pc, (uint8_t *)&ebreak, 2, 0)) {
return -EINVAL;
}
if ((ebreak & 0x3) == 0x3) {
if (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 *)&bp->saved_insn, 2, 1)) {
return -EINVAL;
}
}
Thanks,
drew
> +
> + 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)
> +{
> + /* TODO; To be implemented later. */
> +}
> diff --git a/target/s390x/kvm/kvm.c b/target/s390x/kvm/kvm.c
> index 1b494ecc20..132952cc84 100644
> --- a/target/s390x/kvm/kvm.c
> +++ b/target/s390x/kvm/kvm.c
> @@ -865,7 +865,8 @@ static void determine_sw_breakpoint_instr(void)
> }
> }
>
> -int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> {
> determine_sw_breakpoint_instr();
>
> @@ -877,7 +878,8 @@ int kvm_arch_insert_sw_breakpoint(CPUState *cs, struct
> kvm_sw_breakpoint *bp)
> return 0;
> }
>
> -int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp)
> +int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct kvm_sw_breakpoint *bp,
> + vaddr len)
> {
> uint8_t t[MAX_ILEN];
>
> --
> 2.17.1
>
>