Re: [PATCH v2 1/1] target-riscv: support QMP dump-guest-memory

[Andrew Jones]

On Fri, Dec 18, 2020 at 10:26:53AM +0800, Yifei Jiang wrote:
> Add the support needed for creating prstatus elf notes. Now elf notes
> only contains user_regs. This allows us to use QMP dump-guest-memory.
> 
> Signed-off-by: Yifei Jiang <jiangyifei@huawei.com>
> Signed-off-by: Mingwang Li <limingwang@huawei.com>
> ---
>  target/riscv/arch_dump.c | 189 +++++++++++++++++++++++++++++++++++++++
>  target/riscv/cpu.c       |   2 +
>  target/riscv/cpu.h       |   4 +
>  target/riscv/cpu_bits.h  |   1 +
>  target/riscv/meson.build |   1 +
>  5 files changed, 197 insertions(+)
>  create mode 100644 target/riscv/arch_dump.c
> 
> diff --git a/target/riscv/arch_dump.c b/target/riscv/arch_dump.c
> new file mode 100644
> index 0000000000..b89ddf18c7
> --- /dev/null
> +++ b/target/riscv/arch_dump.c
> @@ -0,0 +1,189 @@
> +/* Support for writing ELF notes for RISC-V architectures
> + *
> + * Copyright (C) 2020 Huawei Technologies Co., Ltd
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2 or later, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along 
> with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "cpu.h"
> +#include "elf.h"
> +#include "sysemu/dump.h"
> +
> +/* struct user_regs_struct from arch/riscv/include/uapi/asm/ptrace.h */
> +struct riscv_user_regs {
> +    target_ulong pc;
> +    target_ulong regs[31];
> +} QEMU_PACKED;
> +
> +/* struct elf_prstatus from include/uapi/linux/elfcore.h */
> +struct riscv64_elf_prstatus {
> +    char pad1[32]; /* 32 == offsetof(struct elf_prstatus, pr_pid) */
> +    uint32_t pr_pid;
> +    char pad2[76]; /* 76 == offsetof(struct elf_prstatus, pr_reg) -
> +                            offsetof(struct elf_prstatus, pr_ppid) */
> +    struct riscv_user_regs pr_reg;
> +    char pad3[8];
> +} QEMU_PACKED;

Any reason not to use the defensive build-bugs that target/arm/arch_dump.c
has?

> +
> +struct riscv64_note {
> +    Elf64_Nhdr hdr;
> +    char name[8]; /* align_up(sizeof("CORE"), 4) */
> +    struct riscv64_elf_prstatus prstatus;
> +} QEMU_PACKED;
> +
> +#define RISCV64_NOTE_HEADER_SIZE offsetof(struct riscv64_note, prstatus)
> +#define RISCV64_PRSTATUS_NOTE_SIZE \
> +            (RISCV64_NOTE_HEADER_SIZE + sizeof(struct riscv64_elf_prstatus))
> +
> +static void riscv64_note_init(struct riscv64_note *note, DumpState *s,
> +                              const char *name, Elf64_Word namesz,
> +                              Elf64_Word type, Elf64_Word descsz)
> +{
> +    memset(note, 0, sizeof(*note));
> +
> +    note->hdr.n_namesz = cpu_to_dump32(s, namesz);
> +    note->hdr.n_descsz = cpu_to_dump32(s, descsz);
> +    note->hdr.n_type = cpu_to_dump32(s, type);
> +
> +    memcpy(note->name, name, namesz);
> +}
> +
> +int riscv_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
> +                               int cpuid, void *opaque)
> +{
> +    struct riscv64_note note;
> +    RISCVCPU *cpu = RISCV_CPU(cs);
> +    CPURISCVState *env = &cpu->env;
> +    DumpState *s = opaque;
> +    int ret, i = 0;
> +    const char name[] = "CORE";
> +
> +    riscv64_note_init(&note, s, name, sizeof(name),
> +                      NT_PRSTATUS, sizeof(note.prstatus));
> +
> +    note.prstatus.pr_pid = cpu_to_dump32(s, cpuid);
> +
> +    note.prstatus.pr_reg.pc = cpu_to_dump64(s, env->pc);
> +
> +    for (i = 0; i < 31; i++) {
> +        note.prstatus.pr_reg.regs[i] = cpu_to_dump64(s, env->gpr[i + 1]);
> +    }
> +
> +    ret = f(&note, RISCV64_PRSTATUS_NOTE_SIZE, s);
> +    if (ret < 0) {
> +        return -1;
> +    }
> +
> +    return ret;
> +}
> +
> +struct riscv32_elf_prstatus {
> +    char pad1[24]; /* 24 == offsetof(struct elf_prstatus, pr_pid) */
> +    uint32_t pr_pid;
> +    char pad2[44]; /* 44 == offsetof(struct elf_prstatus, pr_reg) -
> +                            offsetof(struct elf_prstatus, pr_ppid) */
> +    struct riscv_user_regs pr_reg;
> +    char pad3[4];
> +} QEMU_PACKED;
> +
> +struct riscv32_note {
> +    Elf32_Nhdr hdr;
> +    char name[8]; /* align_up(sizeof("CORE"), 4) */
> +    struct riscv32_elf_prstatus prstatus;
> +} QEMU_PACKED;
> +
> +#define RISCV32_NOTE_HEADER_SIZE offsetof(struct riscv32_note, prstatus)
> +#define RISCV32_PRSTATUS_NOTE_SIZE \
> +            (RISCV32_NOTE_HEADER_SIZE + sizeof(struct riscv32_elf_prstatus))
> +
> +static void riscv32_note_init(struct riscv32_note *note, DumpState *s,
> +                              const char *name, Elf32_Word namesz,
> +                              Elf32_Word type, Elf32_Word descsz)
> +{
> +    memset(note, 0, sizeof(*note));
> +
> +    note->hdr.n_namesz = cpu_to_dump32(s, namesz);
> +    note->hdr.n_descsz = cpu_to_dump32(s, descsz);
> +    note->hdr.n_type = cpu_to_dump32(s, type);
> +
> +    memcpy(note->name, name, namesz);
> +}
> +
> +int riscv_cpu_write_elf32_note(WriteCoreDumpFunction f, CPUState *cs,
> +                               int cpuid, void *opaque)
> +{
> +    struct riscv32_note note;
> +    RISCVCPU *cpu = RISCV_CPU(cs);
> +    CPURISCVState *env = &cpu->env;
> +    DumpState *s = opaque;
> +    int ret, i;
> +    const char name[] = "CORE";
> +
> +    riscv32_note_init(&note, s, name, sizeof(name),
> +                      NT_PRSTATUS, sizeof(note.prstatus));
> +
> +    note.prstatus.pr_pid = cpu_to_dump32(s, cpuid);
> +
> +    note.prstatus.pr_reg.pc = cpu_to_dump32(s, env->pc);
> +
> +    for (i = 0; i < 31; i++) {
> +        note.prstatus.pr_reg.regs[i] = cpu_to_dump32(s, env->gpr[i + 1]);
> +    }
> +
> +    ret = f(&note, RISCV32_PRSTATUS_NOTE_SIZE, s);
> +    if (ret < 0) {
> +        return -1;
> +    }
> +
> +    return ret;
> +}
> +
> +int cpu_get_dump_info(ArchDumpInfo *info,
> +                      const GuestPhysBlockList *guest_phys_blocks)
> +{
> +    RISCVCPU *cpu;
> +    CPURISCVState *env;
> +
> +    if (first_cpu == NULL) {
> +        return -1;
> +    }
> +    cpu = RISCV_CPU(first_cpu);
> +    env = &cpu->env;
> +
> +    info->d_machine = EM_RISCV;
> +
> +#if defined(TARGET_RISCV64)
> +    info->d_class = ELFCLASS64;
> +#else
> +    info->d_class = ELFCLASS32;
> +#endif
> +
> +    info->d_endian = (env->mstatus & MSTATUS_UBE) != 0
> +                     ? ELFDATA2MSB : ELFDATA2LSB;
> +
> +    return 0;
> +}
> +
> +ssize_t cpu_get_note_size(int class, int machine, int nr_cpus)
> +{
> +    size_t note_size;
> +
> +    if (class == ELFCLASS64) {
> +        note_size = RISCV64_PRSTATUS_NOTE_SIZE;
> +    } else {
> +        note_size = RISCV32_PRSTATUS_NOTE_SIZE;
> +    }
> +
> +    return note_size * nr_cpus;
> +}
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 6a0264fc6b..69999af813 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -560,6 +560,8 @@ static void riscv_cpu_class_init(ObjectClass *c, void 
> *data)
>      cc->get_phys_page_debug = riscv_cpu_get_phys_page_debug;
>      /* For now, mark unmigratable: */
>      cc->vmsd = &vmstate_riscv_cpu;
> +    cc->write_elf64_note = riscv_cpu_write_elf64_note;
> +    cc->write_elf32_note = riscv_cpu_write_elf32_note;
>  #endif
>  #ifdef CONFIG_TCG
>      cc->tcg_initialize = riscv_translate_init;
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index c0a326c843..4a340b0c73 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -315,6 +315,10 @@ extern const char * const riscv_intr_names[];
>  
>  const char *riscv_cpu_get_trap_name(target_ulong cause, bool async);
>  void riscv_cpu_do_interrupt(CPUState *cpu);
> +int riscv_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
> +                               int cpuid, void *opaque);
> +int riscv_cpu_write_elf32_note(WriteCoreDumpFunction f, CPUState *cs,
> +                               int cpuid, void *opaque);
>  int riscv_cpu_gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
>  int riscv_cpu_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg);
>  bool riscv_cpu_exec_interrupt(CPUState *cs, int interrupt_request);
> diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
> index 24b24c69c5..d7259561e7 100644
> --- a/target/riscv/cpu_bits.h
> +++ b/target/riscv/cpu_bits.h
> @@ -368,6 +368,7 @@
>  #define MSTATUS_MIE         0x00000008
>  #define MSTATUS_UPIE        0x00000010
>  #define MSTATUS_SPIE        0x00000020
> +#define MSTATUS_UBE         0x00000040
>  #define MSTATUS_MPIE        0x00000080
>  #define MSTATUS_SPP         0x00000100
>  #define MSTATUS_MPP         0x00001800
> diff --git a/target/riscv/meson.build b/target/riscv/meson.build
> index 14a5c62dac..88ab850682 100644
> --- a/target/riscv/meson.build
> +++ b/target/riscv/meson.build
> @@ -26,6 +26,7 @@ riscv_ss.add(files(
>  
>  riscv_softmmu_ss = ss.source_set()
>  riscv_softmmu_ss.add(files(
> +  'arch_dump.c',
>    'pmp.c',
>    'monitor.c',
>    'machine.c'
> -- 
> 2.19.1
> 
>

Besides the missing build-bug question,

Reviewed-by: Andrew Jones <drjones@redhat.com>


Thanks,
drew