Re: [Qemu-devel] [RFC] s390: dump-guest-memory implementation for s390x arch.

[Christian Borntraeger <borntraeger@de.ibm.com>]

On 07/03/13 11:49, Alexander Graf wrote:
> 
> On 28.02.2013, at 10:39, Jens Freimann wrote:
> 
>> From: Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>
>>
>> dump-guest-memory QEMU monitor command didn't work for s390 architecture.
>> The result of the command is supposed to be ELF format 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.
>> target-s390x/arch_memory_mapping.c contains stub functions, current
>> patch places all guest physical memory into the dump.
>>
>> Signed-off-by: Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>
>> Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
>>
>> ---
>> configure                          |   4 +-
>> include/elf.h                      |   6 +
>> target-s390x/Makefile.objs         |   2 +-
>> target-s390x/arch_dump.c           | 240 +++++++++++++++++++++++++++++++++++++
>> target-s390x/arch_memory_mapping.c |  26 ++++
>> 5 files changed, 275 insertions(+), 3 deletions(-)
>> create mode 100644 target-s390x/arch_dump.c
>> create mode 100644 target-s390x/arch_memory_mapping.c
>>
>> diff --git a/configure b/configure
>> index 19738ac..938be14 100755
>> --- a/configure
>> +++ b/configure
>> @@ -4146,7 +4146,7 @@ case "$target_arch2" in
>>     fi
>> esac
>> case "$target_arch2" in
>> -  i386|x86_64)
>> +  i386|x86_64|s390x)
>>     echo "CONFIG_HAVE_GET_MEMORY_MAPPING=y" >> $config_target_mak
>> esac
>> if test "$target_arch2" = "ppc64" -a "$fdt" = "yes"; then
>> @@ -4159,7 +4159,7 @@ if test "$target_softmmu" = "yes" ; then
>>   echo "CONFIG_SOFTMMU=y" >> $config_target_mak
>>   echo "LIBS+=$libs_softmmu $target_libs_softmmu" >> $config_target_mak
>>   case "$target_arch2" in
>> -    i386|x86_64)
>> +    i386|x86_64|s390x)
>>       echo "CONFIG_HAVE_CORE_DUMP=y" >> $config_target_mak
>>   esac
>> fi
>> diff --git a/include/elf.h b/include/elf.h
>> index a21ea53..ba4b3a7 100644
>> --- a/include/elf.h
>> +++ b/include/elf.h
>> @@ -1219,11 +1219,17 @@ typedef struct elf64_shdr {
>>
>> /* Notes used in ET_CORE */
>> #define NT_PRSTATUS	1
>> +#define NT_FPREGSET     2
>> #define NT_PRFPREG	2
>> #define NT_PRPSINFO	3
>> #define NT_TASKSTRUCT	4
>> #define NT_AUXV		6
>> #define NT_PRXFPREG     0x46e62b7f      /* copied from gdb5.1/include/elf/common.h */
>> +#define NT_S390_PREFIX  0x305           /* s390 prefix register */
>> +#define NT_S390_CTRS    0x304           /* s390 control registers */
>> +#define NT_S390_TODPREG 0x303           /* s390 TOD programmable register */
>> +#define NT_S390_TODCMP  0x302           /* s390 TOD clock comparator register */
>> +#define NT_S390_TIMER   0x301           /* s390 timer register */
>>
>>
>> /* Note header in a PT_NOTE section */
>> diff --git a/target-s390x/Makefile.objs b/target-s390x/Makefile.objs
>> index 4e63417..82c79c4 100644
>> --- a/target-s390x/Makefile.objs
>> +++ b/target-s390x/Makefile.objs
>> @@ -1,4 +1,4 @@
>> obj-y += translate.o helper.o cpu.o interrupt.o
>> obj-y += int_helper.o fpu_helper.o cc_helper.o mem_helper.o misc_helper.o
>> -obj-$(CONFIG_SOFTMMU) += ioinst.o
>> +obj-$(CONFIG_SOFTMMU) += ioinst.o arch_dump.o arch_memory_mapping.o
>> obj-$(CONFIG_KVM) += kvm.o
>> diff --git a/target-s390x/arch_dump.c b/target-s390x/arch_dump.c
>> new file mode 100644
>> index 0000000..3098cd1
>> --- /dev/null
>> +++ b/target-s390x/arch_dump.c
>> @@ -0,0 +1,240 @@
>> +/*
>> + * writing ELF notes for s390x arch
>> + *
>> + *  
>> + * Copyright IBM Corp. 2012
>> + *
>> + *     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;
>> +
>> +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];
>> +} 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;
>> +
>> +static int s390x_write_elf64_prstatus(note_t *note, CPUArchState *env)
>> +{
>> +    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_be32(env->psw.mask);
>> +    regs->psw[1] =  cpu_to_be32(env->psw.addr);
>> +    for (i = 0; i <= 15; i++) {
>> +        regs->acrs[i] = cpu_to_be32(env->aregs[i]);
>> +        regs->gprs[i] = cpu_to_be32(env->regs[i]);
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +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_be32(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, write_core_dump_function f,
>> +                                   CPUArchState *env, int id,
>> +                                   void *opaque)
>> +{
>> +    note_t note;
>> +    struct note_func_desc_struct *nf;
>> +    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 = cpu_to_be32(sizeof(note) - sizeof(note.contents) + nf->contents_size);
>> +        ret = f(&note, note_size, opaque);
>> +
>> +        if (ret < 0) {
>> +            return -1;
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +
>> +int cpu_write_elf64_note(write_core_dump_function f, CPUArchState *env,
>> +                         int cpuid, void *opaque)
>> +{
>> +    return s390x_write_all_elf64_notes("CORE", f, 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);
>> +    note_head_size = sizeof(Elf64_Nhdr);
>> +
>> +    assert (machine == EM_S390);
>> +
>> +    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 cpu_write_elf32_note(write_core_dump_function f, CPUArchState *env,
>> +                         int cpuid, void *opaque)
>> +{
>> +    return 0;
>> +}
>> +
>> +
>> +int cpu_write_elf64_qemunote(write_core_dump_function f, CPUArchState *env,
>> +                             void *opaque)
>> +{
>> +    return 0;
>> +}
>> +
>> +int cpu_write_elf32_qemunote(write_core_dump_function f, CPUArchState *env,
>> +                             void *opaque)
>> +{
>> +    return 0;
>> +}
>> +
>> diff --git a/target-s390x/arch_memory_mapping.c b/target-s390x/arch_memory_mapping.c
>> new file mode 100644
>> index 0000000..3dad3b9
>> --- /dev/null
>> +++ b/target-s390x/arch_memory_mapping.c
>> @@ -0,0 +1,26 @@
>> +/*
>> + * s390x memory mapping
>> + *
>> + * Copyright IBM Corp. 2012
>> + *
>> + * Authors:
>> + *     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 "exec/cpu-all.h"
>> +#include "sysemu/memory_mapping.h"
>> +
>> +int cpu_get_memory_mapping(MemoryMappingList *list, CPUArchState *env)
>> +{
>> +    return 0;
>> +}
>> +
>> +bool cpu_paging_enabled(CPUArchState *env)
>> +{
>> +    return false;
> 
> Why? :)

To make things compile :-)
Why no paging? The idea was to have some code that allows getting an ELF dump of a Linux kernel.
All existing tooling for s390 expects real memory dumps. 

Actually having CONFIG_HAVE_GET_MEMORY_MAPPING=n would be a sane thing todo, but IIRC the common
code in dump.c references some functions that are only available with 
CONFIG_HAVE_GET_MEMORY_MAPPING=y. 

/home/cborntra/REPOS/qemu/dump.c:84: undefined reference to `memory_mapping_list_free'
dump.o: In function `dump_init':
/home/cborntra/REPOS/qemu/dump.c:753: undefined reference to `memory_mapping_list_init'
/home/cborntra/REPOS/qemu/dump.c:757: undefined reference to `qemu_get_guest_simple_memory_mapping'
/home/cborntra/REPOS/qemu/dump.c:761: undefined reference to `memory_mapping_filter'

Kate do you remember the details?

Christian