[Crash-utility] [PATCH 1/3] Introduce x86_64_kvtop_pagetable

[Hatayama, Daisuke]

Indoh-san,

> -----Original Message-----
> From: Takao Indoh [mailto:indou.takao at jp.fujitsu.com]
> Sent: Tuesday, October 10, 2017 6:26 PM
> To: crash-utility at redhat.com; Hatayama, Daisuke/畑山 大輔
> <d.hatayama at jp.fujitsu.com>
> Subject: [PATCH 1/3] Introduce x86_64_kvtop_pagetable
> 
> This patch introduces new function x86_64_kvtop_pagetable() to translate
> virtual address to physical address. Unlike x86_64_kvtop(),
> x86_64_kvtop_pagetable() simply converts given virtual address to
> physical address using pagetable.
> 
> To solve kaslr problem of virsh dump and sadump, kaslr offset and
> phys_base need to be calculated before symbol data is loaded. This
> calculation needs translation of kernel virtual address to physical
> address. Current kvtop() implementation tries to use x86_64_VTOP for
> translation at first, but this does not work for this purpose because
> x86_64_VTOP uses phys_base. So x86_64_kvtop_pagetable() is needed which
> does not use phys_base.
> 

Thanks for the patch set.

I don't have comment on this patch.
It looks good to me.

> Signed-off-by: Takao Indoh <indou.takao at jp.fujitsu.com>
> ---
>  defs.h   |  1 +
>  x86_64.c | 26 +++++++++++++++++++++++++-
>  2 files changed, 26 insertions(+), 1 deletion(-)
> 
> diff --git a/defs.h b/defs.h
> index fd97ffe..cddca93 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -5622,6 +5622,7 @@ void x86_64_display_idt_table(void);
>  #define display_idt_table() x86_64_display_idt_table()
>  long x86_64_exception_frame(ulong, ulong, char *, struct bt_info *, FILE *);
>  #define EFRAME_INIT (0)
> +int x86_64_kvtop_pagetable(ulong, physaddr_t *, int);
> 
>  struct x86_64_pt_regs_offsets {
>          long r15;
> diff --git a/x86_64.c b/x86_64.c
> index 44d0c98..fc48425 100644
> --- a/x86_64.c
> +++ b/x86_64.c
> @@ -119,6 +119,7 @@ static int x86_64_verify_paddr(uint64_t);
>  static void GART_init(void);
>  static void x86_64_exception_stacks_init(void);
>  static int in_START_KERNEL_map(ulong);
> +static int __x86_64_kvtop(struct task_context *, ulong, physaddr_t *, int,
> int);
> 
>  struct machine_specific x86_64_machine_specific = { 0 };
> 
> @@ -1964,6 +1965,17 @@ no_upage:
>  	return FALSE;
>  }
> 
> +int
> +x86_64_kvtop_pagetable(ulong kvaddr, physaddr_t *paddr, int verbose)
> +{
> +	return __x86_64_kvtop(NULL, kvaddr, paddr, verbose, 1);
> +}
> +
> +static int
> +x86_64_kvtop(struct task_context *tc, ulong kvaddr, physaddr_t *paddr, int
> verbose)
> +{
> +	return __x86_64_kvtop(tc, kvaddr, paddr, verbose, 0);
> +}
> 
>  /*
>   *  Translates a kernel virtual address to its physical address.  cmd_vtop()
> @@ -1971,7 +1983,7 @@ no_upage:
>   *  other callers quietly accept the translation.
>   */
>  static int
> -x86_64_kvtop(struct task_context *tc, ulong kvaddr, physaddr_t *paddr, int
> verbose)
> +__x86_64_kvtop(struct task_context *tc, ulong kvaddr, physaddr_t *paddr, int
> verbose, int use_pagetable)
>  {
>  	ulong *pml4;
>          ulong *pgd;
> @@ -1985,6 +1997,16 @@ x86_64_kvtop(struct task_context *tc, ulong kvaddr,
> physaddr_t *paddr, int verbo
>  	ulong pte;
>  	physaddr_t physpage;
> 
> +	if (use_pagetable) {
> +		FILL_PML4();
> +		pml4 = ((ulong *)machdep->machspec->pml4) +
> pml4_index(kvaddr);
> +		if (verbose) {
> +			fprintf(fp, "PML4 DIRECTORY: %lx\n",
> vt->kernel_pgd[0]);
> +			fprintf(fp, "PAGE DIRECTORY: %lx\n", *pml4);
> +		}
> +		goto start_vtop_with_pagetable;
> +	}
> +
>          if (!IS_KVADDR(kvaddr))
>                  return FALSE;
> 
> @@ -2031,6 +2053,8 @@ x86_64_kvtop(struct task_context *tc, ulong kvaddr,
> physaddr_t *paddr, int verbo
>                 		fprintf(fp, "PAGE DIRECTORY: %lx\n", *pml4);
>  		}
>  	}
> +
> +start_vtop_with_pagetable:
>  	if (!(*pml4) & _PAGE_PRESENT)
>  		goto no_kpage;
>  	pgd_paddr = (*pml4) & PHYSICAL_PAGE_MASK;
> --
> 2.9.5