Re: [Qemu-devel] [PATCH v3] s390: Implement dump-guest-memory support for target s390x

["Andreas Färber" <afaerber@suse.de>]

Hi Jens,

Am 25.06.2013 12:17, schrieb Jens Freimann:
> With this patch dump-guest-memory on s390 produces an ELF formatted,
> crash-readable dump.
> In order to implement this, the arch-specific part of dump-guest-memory
> was added:
> target-s390x/arch_dump.c contains the whole set of function for writing
> Elf note sections of all types for s390x.
> 
> Signed-off-by: Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>
> Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>

Just some more nitpicks...

> ---
>  include/elf.h              |   6 ++
>  target-s390x/Makefile.objs |   2 +-
>  target-s390x/arch_dump.c   | 229 +++++++++++++++++++++++++++++++++++++++++++++
>  target-s390x/cpu-qom.h     |   5 +
>  target-s390x/cpu.c         |   4 +
>  5 files changed, 245 insertions(+), 1 deletion(-)
>  create mode 100644 target-s390x/arch_dump.c
> 
> diff --git a/include/elf.h b/include/elf.h
> index cf0d3e2..58bfbf8 100644
> --- a/include/elf.h
> +++ b/include/elf.h
> @@ -1348,11 +1348,17 @@ typedef struct elf64_shdr {
>  
>  /* Notes used in ET_CORE */
>  #define NT_PRSTATUS	1
> +#define NT_FPREGSET     2
>  #define NT_PRFPREG	2
>  #define NT_PRPSINFO	3
>  #define NT_TASKSTRUCT	4
>  #define NT_AUXV		6
>  #define NT_PRXFPREG     0x46e62b7f      /* copied from gdb5.1/include/elf/common.h */
> +#define NT_S390_PREFIX  0x305           /* s390 prefix register */
> +#define NT_S390_CTRS    0x304           /* s390 control registers */
> +#define NT_S390_TODPREG 0x303           /* s390 TOD programmable register */
> +#define NT_S390_TODCMP  0x302           /* s390 TOD clock comparator register */
> +#define NT_S390_TIMER   0x301           /* s390 timer register */
>  
>  
>  /* Note header in a PT_NOTE section */
> diff --git a/target-s390x/Makefile.objs b/target-s390x/Makefile.objs
> index 4e63417..c34f654 100644
> --- a/target-s390x/Makefile.objs
> +++ b/target-s390x/Makefile.objs
> @@ -1,4 +1,4 @@
>  obj-y += translate.o helper.o cpu.o interrupt.o
>  obj-y += int_helper.o fpu_helper.o cc_helper.o mem_helper.o misc_helper.o
> -obj-$(CONFIG_SOFTMMU) += ioinst.o
> +obj-$(CONFIG_SOFTMMU) += ioinst.o arch_dump.o
>  obj-$(CONFIG_KVM) += kvm.o
> diff --git a/target-s390x/arch_dump.c b/target-s390x/arch_dump.c
> new file mode 100644
> index 0000000..df95e46
> --- /dev/null
> +++ b/target-s390x/arch_dump.c
> @@ -0,0 +1,229 @@
> +/*
> + * writing ELF notes for s390x arch
> + *
> + *
> + * Copyright IBM Corp. 2012, 2013
> + *
> + *     Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "cpu.h"
> +#include "elf.h"
> +#include "exec/cpu-all.h"
> +#include "sysemu/dump.h"
> +#include "sysemu/kvm.h"
> +
> +
> +struct s390x_user_regs_struct {
> +    uint64_t        psw[2];
> +    uint64_t        gprs[16];
> +    uint32_t        acrs[16];
> +} QEMU_PACKED;
> +
> +typedef struct s390x_user_regs_struct s390x_user_regs;

Are these copied from the kernel or somewhere? QEMU expects CamelCase
for both struct and typedef.

> +
> +struct s390x_elf_prstatus_struct {
> +    uint8_t pad1[32];
> +    uint32_t pid;
> +    uint8_t pad2[76];
> +    s390x_user_regs regs;
> +    uint8_t pad3[16];
> +} QEMU_PACKED;
> +
> +typedef struct s390x_elf_prstatus_struct s390x_elf_prstatus;
> +
> +struct s390x_elf_fpregset_struct {
> +        uint32_t        fpc;
> +        uint32_t        pad;
> +        uint64_t        fprs[16];

Indentation?

> +} QEMU_PACKED;
> +
> +typedef struct s390x_elf_fpregset_struct s390x_elf_fpregset;
> +
> +    typedef struct note_struct {
> +        Elf64_Nhdr hdr;
> +        char name[5];
> +        char pad3[3];
> +        union {
> +            s390x_elf_prstatus prstatus;
> +            s390x_elf_fpregset fpregset;
> +            uint32_t prefix;
> +            uint64_t timer;
> +            uint64_t todcmp;
> +            uint32_t todpreg;
> +            uint64_t ctrs[16];
> +        } contents;
> +    } QEMU_PACKED note_t;

Why indented?

*_t has been criticized as being reserved for POSIX.

> +
> +static int s390x_write_elf64_prstatus(note_t *note, CPUArchState *env)

Please don't use CPUArchState in s390x-only code, use CPUS390XState
where needed; for static helpers please prefer S390CPU.

`git grep CPUArchState` flags to me where I still need to touch things,
same for ENV_GET_CPU() (which Jason recently introduced, fix upcoming).

> +{
> +    int i;
> +    s390x_user_regs *regs;
> +
> +    note->hdr.n_type = cpu_to_be32(NT_PRSTATUS);
> +
> +    regs = &(note->contents.prstatus.regs);
> +    regs->psw[0] =  cpu_to_be64(env->psw.mask);
> +    regs->psw[1] =  cpu_to_be64(env->psw.addr);

Two spaces accidental?

> +    for (i = 0; i <= 15; i++) {
> +        regs->acrs[i] = cpu_to_be32(env->aregs[i]);
> +        regs->gprs[i] = cpu_to_be64(env->regs[i]);
> +    }
> +
> +    return 0;
> +}

Already returns 0, make it void? Same for all callbacks below.

> +
> +static int s390x_write_elf64_fpregset(note_t *note, CPUArchState *env)
> +{
> +    int i;
> +
> +    note->hdr.n_type = cpu_to_be32(NT_FPREGSET);
> +
> +    note->contents.fpregset.fpc = cpu_to_be32(env->fpc);
> +    for (i = 0; i <= 15; i++) {
> +        note->contents.fpregset.fprs[i] =  cpu_to_be64(env->fregs[i].ll);
> +    }
> +
> +    return 0;
> +}
> +
> +
> +static int s390x_write_elf64_timer(note_t *note, CPUArchState *env)
> +{
> +    note->hdr.n_type = cpu_to_be32(NT_S390_TIMER);
> +
> +    note->contents.timer = cpu_to_be64((uint64_t)(env->cputm));
> +
> +    return 0;
> +}
> +
> +static int s390x_write_elf64_todcmp(note_t *note, CPUArchState *env)
> +{
> +    note->hdr.n_type = cpu_to_be32(NT_S390_TODCMP);
> +
> +    note->contents.todcmp = cpu_to_be64((uint64_t)(env->ckc));
> +
> +    return 0;
> +}
> +
> +static int s390x_write_elf64_todpreg(note_t *note, CPUArchState *env)
> +{
> +    note->hdr.n_type = cpu_to_be32(NT_S390_TODPREG);
> +
> +    note->contents.todpreg = cpu_to_be32((uint32_t)(env->todpr));
> +
> +    return 0;
> +}
> +
> +static int s390x_write_elf64_ctrs(note_t *note, CPUArchState *env)
> +{
> +    int i;
> +
> +    note->hdr.n_type = cpu_to_be32(NT_S390_CTRS);
> +
> +    for (i = 0; i <= 15; i++) {
> +        note->contents.ctrs[i] =  cpu_to_be64(env->cregs[i]);
> +    }
> +
> +    return 0;
> +}
> +
> +static int s390x_write_elf64_prefix(note_t *note, CPUArchState *env)
> +{
> +    note->hdr.n_type = cpu_to_be32(NT_S390_PREFIX);
> +
> +    note->contents.prefix = cpu_to_be32((uint32_t)(env->psa));
> +
> +    return 0;
> +}
> +
> +
> +struct note_func_desc_struct {
> +    int contents_size;
> +    int (*note_contents_func)(note_t *note, CPUArchState *env);
> +} note_func[] = {
> +    {sizeof(((note_t *)0)->contents.prstatus), s390x_write_elf64_prstatus},
> +    {sizeof(((note_t *)0)->contents.prefix),   s390x_write_elf64_prefix},
> +    {sizeof(((note_t *)0)->contents.fpregset), s390x_write_elf64_fpregset},
> +    {sizeof(((note_t *)0)->contents.ctrs),     s390x_write_elf64_ctrs},
> +    {sizeof(((note_t *)0)->contents.timer),    s390x_write_elf64_timer},
> +    {sizeof(((note_t *)0)->contents.todcmp),   s390x_write_elf64_todcmp},
> +    {sizeof(((note_t *)0)->contents.todpreg),  s390x_write_elf64_todpreg},
> +    { 0, NULL}
> +};
> +
> +
> +static int s390x_write_all_elf64_notes(const char *note_name,
> +                                   WriteCoreDumpFunction f,
> +                                   CPUArchState *env, int id,
> +                                   void *opaque)

Odd indentation?

> +{
> +    note_t note;
> +    struct note_func_desc_struct *nf;

typedef and CamelCase

> +    int note_size;
> +    int ret = -1;
> +
> +    for (nf = note_func; nf->note_contents_func; nf++) {
> +        note.hdr.n_namesz = cpu_to_be32(sizeof(note.name));
> +        note.hdr.n_descsz = cpu_to_be32(nf->contents_size);
> +        strncpy(note.name, note_name, sizeof(note.name));
> +        ret = (*nf->note_contents_func)(&note, env);
> +
> +        note_size = sizeof(note) - sizeof(note.contents) + nf->contents_size;
> +        ret = f(&note, note_size, opaque);
> +
> +        if (ret < 0) {
> +            return -1;
> +        }
> +
> +    }
> +
> +    return 0;
> +}
> +
> +
> +int s390_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
> +                              int cpuid, void *opaque)
> +{
> +    S390CPU *cpu = S390_CPU(cs);

Here you have the S390CPU that you could just pass on.

> +    return s390x_write_all_elf64_notes("CORE", f, &cpu->env, cpuid, opaque);
> +}
> +
> +int cpu_get_dump_info(ArchDumpInfo *info)
> +{
> +    info->d_machine = EM_S390;
> +    info->d_endian = ELFDATA2MSB;
> +    info->d_class = ELFCLASS64;
> +
> +    return 0;
> +}
> +
> +ssize_t cpu_get_note_size(int class, int machine, int nr_cpus)
> +{
> +    int name_size = 8; /* "CORE" or "QEMU" rounded */
> +    size_t elf_note_size = 0;
> +    int note_head_size;
> +    struct note_func_desc_struct *nf;
> +
> +    assert(class == ELFCLASS64);
> +    assert(machine == EM_S390);
> +
> +    note_head_size = sizeof(Elf64_Nhdr);
> +
> +    for (nf = note_func; nf->note_contents_func; nf++) {
> +        elf_note_size = elf_note_size + note_head_size + name_size +
> +                        nf->contents_size;
> +    }
> +
> +    return (elf_note_size) * nr_cpus;
> +}
> +
> +int s390_cpu_write_elf64_qemunote(WriteCoreDumpFunction f,
> +        CPUState *env, void *opaque)

Please don't mix env with CPUState. Indentation?

> +{
> +    return 0;
> +}
> diff --git a/target-s390x/cpu-qom.h b/target-s390x/cpu-qom.h
> index 34d45c2..6327802 100644
> --- a/target-s390x/cpu-qom.h
> +++ b/target-s390x/cpu-qom.h
> @@ -72,5 +72,10 @@ static inline S390CPU *s390_env_get_cpu(CPUS390XState *env)
>  #define ENV_OFFSET offsetof(S390CPU, env)
>  
>  void s390_cpu_do_interrupt(CPUState *cpu);
> +int s390_cpu_write_elf64_note(WriteCoreDumpFunction f, CPUState *cs,
> +                         int cpuid, void *opaque);
> +
> +int s390_cpu_write_elf64_qemunote(WriteCoreDumpFunction f,
> +         CPUState *env, void *opaque);

Consistent indentation?

>  
>  #endif
> diff --git a/target-s390x/cpu.c b/target-s390x/cpu.c
> index 23fe51f..9376a6c 100644
> --- a/target-s390x/cpu.c
> +++ b/target-s390x/cpu.c
> @@ -171,6 +171,10 @@ static void s390_cpu_class_init(ObjectClass *oc, void *data)
>  
>      cc->do_interrupt = s390_cpu_do_interrupt;
>      dc->vmsd = &vmstate_s390_cpu;
> +#ifndef CONFIG_USER_ONLY
> +    cc->write_elf64_note = s390_cpu_write_elf64_note;
> +    cc->write_elf64_qemunote = s390_cpu_write_elf64_qemunote;
> +#endif
>  }
>  
>  static const TypeInfo s390_cpu_type_info = {

Regards,
Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg