[Crash-utility] [PATCH] Add ELF core dump support for s390x
Dave Anderson
anderson at redhat.com
Thu Feb 11 16:13:52 UTC 2010
----- "Michael Holzheu" <holzheu at linux.vnet.ibm.com> wrote:
> Hi Dave,
>
> Next patch...
>
> We will have ELF core dumps on s390x in the near future:
>
> This patch enables crash for reading s390x (64 bit) ELF core dumps. The
> following new ELF note sections are added by this patch:
>
> * NT_FPREGSET: Floating point registers - all architectures
> * NT_S390_TIMER: S390 CPU timer
> * NT_S390_TODCMP: S390 TOD clock comparator
> * NT_S390_TODPREG: S390 TOD programmable register
> * NT_S390_CTRS: S390 control registers
> * NT_S390_PREFIX: S390 prefix register
>
> The mapping of a s390 CPU to the correct note number is done via the prefix
> register of the CPUs. This is implemented in s390x_get_note_nr(). The
> function gets the prefix register for the logical CPU number from the lowcore
> pointer array (global variable lowcore_ptr) and searches the matching prefix
> register note.
>
> If CPU information is found in the dump for a running task, it is converted
> into a generic s390x_cpu structure which is then attached to "bt->machdep".
> If "bt->machdep" is set, the s390x "machdep->get_stack_frame()" function uses
> that register information.
OK, first the simple stuff...
The change to is_shared_object() doesn't make sense to me.
That function is only used when loading extension modules.
You make the following change in the ELFCLASS32 section.
So if a 32-bit s390 crash session attempts to load a 32-bit
s390 extension module, your patch will cause it to fall
through and fail:
--- a/symbols.c
+++ b/symbols.c
@@ -2710,7 +2710,7 @@ is_shared_object(char *file)
break;
case EM_S390:
- if (machine_type("S390"))
+ if (machine_type("S390X"))
return TRUE;
break;
How can that work?
Anyway, on to the the bigger picture...
--- a/netdump.h
+++ b/netdump.h
@@ -68,6 +68,12 @@ struct vmcore_data {
ulong switch_stack;
uint num_prstatus_notes;
void *nt_prstatus_percpu[NR_CPUS];
+ void *nt_fpregset_percpu[NR_CPUS];
+ void *nt_s390_timer_percpu[NR_CPUS];
+ void *nt_s390_todcmp_percpu[NR_CPUS];
+ void *nt_s390_todpreg_percpu[NR_CPUS];
+ void *nt_s390_ctrs_percpu[NR_CPUS];
+ void *nt_s390_prefix_percpu[NR_CPUS];
struct xen_kdump_data *xen_kdump_data;
void *vmcoreinfo;
uint size_vmcoreinfo;
This is bit hard to swallow. A while back I went through and purged
several prior static declarations of data structures that used arrays
indexed with NR_CPUS -- replacing them with pointers that dynamically
allocated the arrays when the actual number of cpus was known.
I really don't want to ever *add* any new instances of static arrays
indexed with NR_CPUS. Now you could argue that the currently-existing
nt_prstatus_percpu[NR_CPUS] is there, but that should probably be changed
to malloc() NR_CPUS-worth during the dumpfile discovery phase, and then
do a realloc() later on when the actual number of cpus is determined.
Anyway, the x86_64 and ia64 arches are up to 4096 NR_CPUS, so your patch
adds ~200k of useless static data for those architectures. So I suggest
suggest that all of your new NR_CPU-indexed fields -- none of which are
of any interest to the other architectures -- should be moved into s390x.c,
and then just a single pointer to the collective data could be put into
the vmcore_data structure. (i.e., similar to the xen_kdump_data pointer).
Let's keep the vmcore_data structure as generic as possible.
Also BTW, there's a lot work d one reading/saving the new note data,
but once that's accomplished, I don't see where the data is ever
used? What's the point of saving it if it's not referred
to somewhere later on? You couldn't even look at it unless
you ran a gdb on the crash session. Or am I missing something?
I see the temporary bt->machdep reference to the static s390x_cpu
data structure in get_netdump_regs_s390x(). But I would think
that if you're going to the trouble to save all of that data,
that you might want to put the s390x_cpu structure in s390x,
and then maybe dump its data in s390x_dump_machdep_table()
via "help -m".
Now, the NT_S390_XXX defines -- were did they originate exactly?
If I google them -- all I get is a reference to your 2-hour old
crash-utility mailing list post! Anyway, I haven't tried compiling
it, but given that they are all #define'd in the "#ifdef S390X" section
of defs.h, then netdump.c couldn't possibly compile for any other arch.
Also, the NT_S390_XXX numerical values are probably safe and would never
be misconstrued, but the NT_FPREGSET note is the only new note section
that could conceivably show up in some other architecture, so that
should be restricted to s390x only.
What do you think?
Dave
>
> ---
> defs.h | 66 ++++++++++++++++++++++++
> netdump.c | 164
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> netdump.h | 6 ++
> s390x.c | 34 ++++++++++--
> symbols.c | 2
> 5 files changed, 264 insertions(+), 8 deletions(-)
>
> --- a/defs.h
> +++ b/defs.h
> @@ -2747,6 +2747,71 @@ struct efi_memory_desc_t {
> #define _SECTION_SIZE_BITS 28
> #define _MAX_PHYSMEM_BITS 42
>
> +/*
> + * S390 CPU timer ELF note
> + */
> +#ifndef NT_S390_TIMER
> +#define NT_S390_TIMER 0x301
> +#endif
> +
> +/*
> + * S390 TOD clock comparator ELF note
> + */
> +#ifndef NT_S390_TODCMP
> +#define NT_S390_TODCMP 0x302
> +#endif
> +
> +/*
> + * S390 TOD programmable register ELF note
> + */
> +#ifndef NT_S390_TODPREG
> +#define NT_S390_TODPREG 0x303
> +#endif
> +
> +/*
> + * S390 control registers ELF note
> + */
> +#ifndef NT_S390_CTRS
> +#define NT_S390_CTRS 0x304
> +#endif
> +
> +/*
> + * S390 prefix ELF note
> + */
> +#ifndef NT_S390_PREFIX
> +#define NT_S390_PREFIX 0x305
> +#endif
> +
> +/*
> + * S390 floating point register ELF Note
> + */
> +#ifndef NT_FPREGSET
> +#define NT_FPREGSET 0x2
> +#endif
> +
> +struct nt_s390_fpregset_64 {
> + uint32_t fpc;
> + uint32_t pad;
> + uint64_t fprs[16];
> +} __attribute__ ((packed));
> +
> +/*
> + * s390x CPU info
> + */
> +struct s390x_cpu
> +{
> + uint64_t gprs[16];
> + uint64_t ctrs[16];
> + uint32_t acrs[16];
> + uint64_t fprs[16];
> + uint32_t fpc;
> + uint64_t psw[2];
> + uint32_t prefix;
> + uint64_t timer;
> + uint64_t todcmp;
> + uint32_t todpreg;
> +};
> +
> #endif /* S390X */
>
> #ifdef PLATFORM
> @@ -4196,6 +4261,7 @@ void get_netdump_regs(struct bt_info *,
> int is_partial_netdump(void);
> void get_netdump_regs_x86(struct bt_info *, ulong *, ulong *);
> void get_netdump_regs_x86_64(struct bt_info *, ulong *, ulong *);
> +void get_netdump_regs_s390x(struct bt_info *, ulong *, ulong *);
> struct vmcore_data;
> struct vmcore_data *get_kdump_vmcore_data(void);
> int read_kdump(int, void *, int, ulong, physaddr_t);
> --- a/netdump.c
> +++ b/netdump.c
> @@ -213,6 +213,11 @@ is_netdump(char *file, ulong source_quer
> goto bailout;
> break;
>
> + case EM_S390:
> + if (machine_type_mismatch(file, "S390X", NULL,
> + source_query))
> + goto bailout;
> + break;
> case EM_386:
> if (machine_type_mismatch(file, "X86", NULL,
> source_query))
> @@ -1858,6 +1863,72 @@ dump_Elf64_Nhdr(Elf64_Off offset, int st
> }
> }
> break;
> + case NT_FPREGSET:
> + netdump_print("(NT_FPREGSET)");
> + if (store) {
> + for (i = 0; i < NR_CPUS; i++) {
> + if (nd->nt_fpregset_percpu[i])
> + continue;
> + nd->nt_fpregset_percpu[i] = (void *)note;
> + break;
> + }
> + }
> + break;
> + case NT_S390_TIMER:
> + netdump_print("(NT_S390_TIMER)\n");
> + if (store) {
> + for (i = 0; i < NR_CPUS; i++) {
> + if (nd->nt_s390_timer_percpu[i])
> + continue;
> + nd->nt_s390_timer_percpu[i] = (void *)note;
> + break;
> + }
> + }
> + break;
> + case NT_S390_TODCMP:
> + netdump_print("(NT_S390_TODCMP)\n");
> + if (store) {
> + for (i = 0; i < NR_CPUS; i++) {
> + if (nd->nt_s390_todcmp_percpu[i])
> + continue;
> + nd->nt_s390_todcmp_percpu[i] = (void *)note;
> + break;
> + }
> + }
> + break;
> + case NT_S390_TODPREG:
> + netdump_print("(NT_S390_TODPREG)\n");
> + if (store) {
> + for (i = 0; i < NR_CPUS; i++) {
> + if (nd->nt_s390_todpreg_percpu[i])
> + continue;
> + nd->nt_s390_todpreg_percpu[i] = (void *)note;
> + break;
> + }
> + }
> + break;
> + case NT_S390_CTRS:
> + netdump_print("(NT_S390_CTRS)\n");
> + if (store) {
> + for (i = 0; i < NR_CPUS; i++) {
> + if (nd->nt_s390_ctrs_percpu[i])
> + continue;
> + nd->nt_s390_ctrs_percpu[i] = (void *)note;
> + break;
> + }
> + }
> + break;
> + case NT_S390_PREFIX:
> + netdump_print("(NT_S390_PREFIX)\n");
> + if (store) {
> + for (i = 0; i < NR_CPUS; i++) {
> + if (nd->nt_s390_prefix_percpu[i])
> + continue;
> + nd->nt_s390_prefix_percpu[i] = (void *)note;
> + break;
> + }
> + }
> + break;
> case NT_PRPSINFO:
> netdump_print("(NT_PRPSINFO)\n");
> if (store)
> @@ -2082,6 +2153,9 @@ get_netdump_regs(struct bt_info *bt, ulo
> return get_netdump_regs_x86_64(bt, eip, esp);
> break;
>
> + case EM_S390:
> + get_netdump_regs_s390x(bt, eip, esp);
> + break;
> default:
> error(FATAL,
> "support for ELF machine type %d not available\n",
> @@ -2381,6 +2455,96 @@ get_netdump_regs_ppc64(struct bt_info *b
> machdep->get_stack_frame(bt, eip, esp);
> }
>
> +static void *
> +get_note_desc(Elf64_Nhdr *note)
> +{
> + void *ptr = note;
> +
> + return ptr + roundup(sizeof(*note) + note->n_namesz, 4);
> +}
> +
> +static int
> +s390x_get_note_nr(struct bt_info *bt)
> +{
> + unsigned int cpu = bt->tc->processor;
> + unsigned long lowcore_ptr, prefix;
> + uint32_t *nt_prefix;
> + unsigned int i;
> +
> + lowcore_ptr = symbol_value("lowcore_ptr");
> + readmem(lowcore_ptr + cpu * sizeof(long), KVADDR,
> + &prefix, sizeof(long), "lowcore_ptr", FAULT_ON_ERROR);
> + for (i = 0; i < nd->num_prstatus_notes; i++) {
> + nt_prefix = get_note_desc(nd->nt_s390_prefix_percpu[i]);
> + if (*nt_prefix == prefix)
> + return i;
> + }
> + error(FATAL, "cannot determine NT_PRSTATUS ELF note for task:
> %lx\n",
> + bt->task);
> +}
> +
> +static void
> +s390x_note_to_s390x_cpu(struct s390x_cpu *s390x_cpu, int note_nr)
> +{
> + struct nt_s390_fpregset_64 *nt_s390_fpregset;
> + Elf64_Nhdr *note;
> + char *ptr;
> +
> + /* Copy prstatus note */
> + note = (Elf64_Nhdr *) nd->nt_prstatus_percpu[note_nr];
> + ptr = get_note_desc(note) + MEMBER_OFFSET("elf_prstatus",
> "pr_reg");
> + memcpy(&s390x_cpu->psw, ptr, sizeof(s390x_cpu->psw));
> + memcpy(&s390x_cpu->gprs, ptr + 16, sizeof(s390x_cpu->gprs));
> + memcpy(&s390x_cpu->acrs, ptr + 16 + 16 * 8,
> sizeof(s390x_cpu->acrs));
> +
> + /* Copy s390 floating point register note */
> + nt_s390_fpregset = get_note_desc(nd->nt_fpregset_percpu[note_nr]);
> + memcpy(&s390x_cpu->fpc, &nt_s390_fpregset->fpc,
> + sizeof(s390x_cpu->fpc));
> + memcpy(&s390x_cpu->fprs, &nt_s390_fpregset->fprs,
> + sizeof(s390x_cpu->fprs));
> +
> + /* Copy s390 additional notes */
> + memcpy(&s390x_cpu->timer,
> + get_note_desc(nd->nt_s390_timer_percpu[note_nr]),
> + sizeof(s390x_cpu->timer));
> + memcpy(&s390x_cpu->todcmp,
> + get_note_desc(nd->nt_s390_todcmp_percpu[note_nr]),
> + sizeof(s390x_cpu->todcmp));
> + memcpy(&s390x_cpu->todpreg,
> + get_note_desc(nd->nt_s390_todpreg_percpu[note_nr]),
> + sizeof(s390x_cpu->todpreg));
> + memcpy(&s390x_cpu->ctrs,
> + get_note_desc(nd->nt_s390_ctrs_percpu[note_nr]),
> + sizeof(s390x_cpu->ctrs));
> + memcpy(&s390x_cpu->prefix,
> + get_note_desc(nd->nt_s390_prefix_percpu[note_nr]),
> + sizeof(s390x_cpu->prefix));
> +}
> +
> +void
> +get_netdump_regs_s390x(struct bt_info *bt, ulong *eip, ulong *esp)
> +{
> + static struct s390x_cpu s390x_cpu;
> + unsigned int note_nr;
> + Elf64_Nhdr *note;
> +
> + bt->machdep = NULL;
> + if (nd->num_prstatus_notes == 0)
> + goto out;
> + if (!(is_task_active(bt->task) &&
> + (kt->cpu_flags[bt->tc->processor] & ONLINE)))
> + goto out;
> + note_nr = s390x_get_note_nr(bt);
> + if (!nd->nt_prstatus_percpu[note_nr])
> + error(FATAL, "cannot determine NT_PRSTATUS ELF note for "
> + "task: %lx\n", bt->task);
> + s390x_note_to_s390x_cpu(&s390x_cpu, note_nr);
> + bt->machdep = &s390x_cpu;
> +out:
> + machdep->get_stack_frame(bt, eip, esp);
> +}
> +
> int
> is_partial_netdump(void)
> {
> --- a/netdump.h
> +++ b/netdump.h
> @@ -68,6 +68,12 @@ struct vmcore_data {
> ulong switch_stack;
> uint num_prstatus_notes;
> void *nt_prstatus_percpu[NR_CPUS];
> + void *nt_fpregset_percpu[NR_CPUS];
> + void *nt_s390_timer_percpu[NR_CPUS];
> + void *nt_s390_todcmp_percpu[NR_CPUS];
> + void *nt_s390_todpreg_percpu[NR_CPUS];
> + void *nt_s390_ctrs_percpu[NR_CPUS];
> + void *nt_s390_prefix_percpu[NR_CPUS];
> struct xen_kdump_data *xen_kdump_data;
> void *vmcoreinfo;
> uint size_vmcoreinfo;
> --- a/s390x.c
> +++ b/s390x.c
> @@ -56,7 +56,6 @@ static ulong s390x_processor_speed(void)
> static int s390x_eframe_search(struct bt_info *);
> static void s390x_back_trace_cmd(struct bt_info *);
> static void s390x_dump_irq(int);
> -static void s390x_get_stack_frame(struct bt_info *, ulong *, ulong
> *);
> static int s390x_dis_filter(ulong, char *);
> static void s390x_cmd_mach(void);
> static int s390x_get_smp_cpus(void);
> @@ -64,6 +63,7 @@ static void s390x_display_machine_stats(
> static void s390x_dump_line_number(ulong);
> static struct line_number_hook s390x_line_number_hooks[];
> static int s390x_is_uvaddr(ulong, struct task_context *);
> +static void s390x_get_stack_frame(struct bt_info *, ulong *, ulong
> *);
>
>
> /*
> @@ -571,15 +571,36 @@ s390x_has_cpu(struct bt_info *bt)
> * read lowcore for cpu
> */
> static void
> -s390x_get_lowcore(int cpu, char* lowcore)
> +s390x_get_lowcore(struct bt_info *bt, char* lowcore)
> {
> unsigned long lowcore_array,lowcore_ptr;
> + struct s390x_cpu *s390x_cpu;
> + int cpu = bt->tc->processor;
>
> lowcore_array = symbol_value("lowcore_ptr");
> readmem(lowcore_array + cpu * S390X_WORD_SIZE,KVADDR,
> - &lowcore_ptr, sizeof(long), "lowcore_ptr", FAULT_ON_ERROR);
> - readmem(lowcore_ptr, KVADDR, lowcore, LOWCORE_SIZE, "lowcore",
> + &lowcore_ptr, sizeof(long), "lowcore_ptr",
> FAULT_ON_ERROR);
> + readmem(lowcore_ptr, KVADDR, lowcore, LOWCORE_SIZE, "lowcore",
> FAULT_ON_ERROR);
> +
> + if (!bt->machdep)
> + return;
> +
> + s390x_cpu = bt->machdep;
> + /* Copy ELF register information to defined places in lowcore */
> + memcpy(lowcore + 4864, &s390x_cpu->psw, sizeof(s390x_cpu->psw));
> + memcpy(lowcore + 4736, &s390x_cpu->gprs, sizeof(s390x_cpu->gprs));
> + memcpy(lowcore + 4928, &s390x_cpu->acrs, sizeof(s390x_cpu->acrs));
> +
> + memcpy(lowcore + 4892, &s390x_cpu->fpc, sizeof(s390x_cpu->fpc));
> + memcpy(lowcore + 4608, &s390x_cpu->fprs, sizeof(s390x_cpu->fprs));
> +
> + memcpy(lowcore + 4888, &s390x_cpu->prefix,
> sizeof(s390x_cpu->prefix));
> + memcpy(lowcore + 4992, &s390x_cpu->ctrs, sizeof(s390x_cpu->ctrs));
> +
> + memcpy(lowcore + 4900, &s390x_cpu->todpreg,
> sizeof(s390x_cpu->todpreg));
> + memcpy(lowcore + 4904, &s390x_cpu->timer,
> sizeof(s390x_cpu->timer));
> + memcpy(lowcore + 4912, &s390x_cpu->todcmp,
> sizeof(s390x_cpu->todcmp));
> }
>
> /*
> @@ -627,7 +648,7 @@ s390x_back_trace_cmd(struct bt_info *bt)
> fprintf(fp,"(active)\n");
> return;
> }
> - s390x_get_lowcore(cpu,lowcore);
> + s390x_get_lowcore(bt, lowcore);
> psw_flags = ULONG(lowcore + OFFSET(s390_lowcore_psw_save_area));
>
> if(psw_flags & 0x1000000000000ULL){
> @@ -908,7 +929,7 @@ s390x_get_stack_frame(struct bt_info *bt
> char lowcore[LOWCORE_SIZE];
>
> if(s390x_has_cpu(bt))
> - s390x_get_lowcore(s390x_cpu_of_task(bt->task),lowcore);
> + s390x_get_lowcore(bt, lowcore);
>
> /* get the stack pointer */
> if(esp){
> @@ -1139,5 +1160,4 @@ try_closest:
> }
> }
> }
> -
> #endif
> --- a/symbols.c
> +++ b/symbols.c
> @@ -2710,7 +2710,7 @@ is_shared_object(char *file)
> break;
>
> case EM_S390:
> - if (machine_type("S390"))
> + if (machine_type("S390X"))
> return TRUE;
> break;
> }
>
>
> --
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