[Crash-utility] [PATCH] sadump: Fix a problem of PTI enabled kernel
Hatayama, Daisuke
d.hatayama at jp.fujitsu.com
Fri Jan 26 06:56:16 UTC 2018
> -----Original Message-----
> From: Takao Indoh [mailto:indou.takao at jp.fujitsu.com]
> Sent: Friday, January 26, 2018 9:26 AM
> To: crash-utility at redhat.com; Hatayama, Daisuke
> <d.hatayama at jp.fujitsu.com>
> Subject: [PATCH] sadump: Fix a problem of PTI enabled kernel
>
> This patch fixes a problem that a dumpfile of sadump cannot be opened
> by crash when Page Table Isolation(PTI) is enabled.
>
> When PTI is enabled, bit 12 of CR3 register is used to split user
> space and kernel space. Also bit 11:0 is used for Process Context
> IDentifiers(PCID). To open a dump file of sadump, a value of CR3 is
> used to calculate KASLR offset and phys_base, therefore this patch
> fixes to mask CR3 register value collectly for PTI enabled kernel.
>
> This patch also includes code cleanup.
>
> Signed-off-by: Takao Indoh <indou.takao at jp.fujitsu.com>
> ---
> defs.h | 2 ++
> sadump.c | 33 +++++++++++++++++++++------------
> symbols.c | 9 +++++++++
> 3 files changed, 32 insertions(+), 12 deletions(-)
>
> diff --git a/defs.h b/defs.h
> index dcd6c26..a19f280 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2605,6 +2605,8 @@ struct symbol_table_data {
> ulong divide_error_vmlinux;
> ulong idt_table_vmlinux;
> ulong saved_command_line_vmlinux;
> + ulong pti_init_vmlinux;
> + ulong kaiser_init_vmlinux;
> };
>
> /* flags for st */
> diff --git a/sadump.c b/sadump.c
> index 6b912d4..25cefe9 100644
> --- a/sadump.c
> +++ b/sadump.c
> @@ -1749,7 +1749,7 @@ static ulong memparse(char *ptr, char **retptr)
> * of elfcorehdr.
> */
> static ulong
> -get_elfcorehdr(ulong cr3, ulong kaslr_offset)
> +get_elfcorehdr(ulong kaslr_offset)
> {
> char cmdline[BUFSIZE], *ptr;
> ulong cmdline_vaddr;
> @@ -1906,7 +1906,7 @@ get_vmcoreinfo(ulong elfcorehdr, ulong *addr, int *len)
> * using "elfcorehdr=" and retrieve kaslr_offset/phys_base from
> vmcoreinfo.
> */
> static int
> -get_kaslr_offset_from_vmcoreinfo(ulong cr3, ulong orig_kaslr_offset,
> +get_kaslr_offset_from_vmcoreinfo(ulong orig_kaslr_offset,
> ulong *kaslr_offset, ulong *phys_base)
> {
> ulong elfcorehdr_addr = 0;
> @@ -1916,7 +1916,7 @@ get_kaslr_offset_from_vmcoreinfo(ulong cr3, ulong
> orig_kaslr_offset,
> int ret = FALSE;
>
> /* Find "elfcorehdr=" in the kernel boot parameter */
> - elfcorehdr_addr = get_elfcorehdr(cr3, orig_kaslr_offset);
> + elfcorehdr_addr = get_elfcorehdr(orig_kaslr_offset);
> if (!elfcorehdr_addr)
> return FALSE;
>
> @@ -1973,8 +1973,8 @@ quit:
> * 1) Get IDTR and CR3 value from the dump header.
> * 2) Get a virtual address of IDT from IDTR value
> * --- (A)
> - * 3) Translate (A) to physical address using CR3, which points a top of
> - * page table.
> + * 3) Translate (A) to physical address using CR3, the upper 52 bits
> + * of which points a top of page table.
> * --- (B)
> * 4) Get an address of vector0 (Devide Error) interrupt handler from
> * IDT, which are pointed by (B).
> @@ -2023,12 +2023,15 @@ quit:
> * kernel. Retrieve vmcoreinfo from address of "elfcorehdr=" and
> * get kaslr_offset and phys_base from vmcoreinfo.
> */
> +#define PTI_USER_PGTABLE_BIT PAGE_SHIFT
> +#define PTI_USER_PGTABLE_MASK (1 << PTI_USER_PGTABLE_BIT)
> +#define CR3_PCID_MASK 0xFFFull
> int
> sadump_calc_kaslr_offset(ulong *kaslr_offset)
> {
> ulong phys_base = 0;
> struct sadump_smram_cpu_state scs;
> - uint64_t idtr = 0, cr3 = 0, idtr_paddr;
> + uint64_t idtr = 0, pgd = 0, idtr_paddr;
> ulong divide_error_vmcore;
> ulong kaslr_offset_kdump, phys_base_kdump;
> int ret = FALSE;
> @@ -2039,7 +2042,10 @@ sadump_calc_kaslr_offset(ulong *kaslr_offset)
>
> memset(&scs, 0, sizeof(scs));
> get_sadump_smram_cpu_state_any(&scs);
> - cr3 = scs.Cr3;
> + if (st->pti_init_vmlinux || st->kaiser_init_vmlinux)
> + pgd = scs.Cr3 & ~(CR3_PCID_MASK|PTI_USER_PGTABLE_MASK);
> + else
> + pgd = scs.Cr3 & ~CR3_PCID_MASK;
> idtr = ((uint64_t)scs.IdtUpper)<<32 | (uint64_t)scs.IdtLower;
>
> /*
> @@ -2050,12 +2056,12 @@ sadump_calc_kaslr_offset(ulong *kaslr_offset)
> *
> * TODO: XEN and 5-level is not supported
> */
> - vt->kernel_pgd[0] = cr3;
> + vt->kernel_pgd[0] = pgd;
> machdep->machspec->last_pml4_read = vt->kernel_pgd[0];
> machdep->machspec->physical_mask_shift =
> __PHYSICAL_MASK_SHIFT_2_6;
> machdep->machspec->pgdir_shift = PGDIR_SHIFT;
> - if (!readmem(cr3, PHYSADDR, machdep->machspec->pml4, PAGESIZE(),
> - "cr3", RETURN_ON_ERROR))
> + if (!readmem(pgd, PHYSADDR, machdep->machspec->pml4, PAGESIZE(),
> + "pgd", RETURN_ON_ERROR))
> goto quit;
>
> /* Convert virtual address of IDT table to physical address */
> @@ -2070,7 +2076,7 @@ sadump_calc_kaslr_offset(ulong *kaslr_offset)
>
> if (CRASHDEBUG(1)) {
> fprintf(fp, "calc_kaslr_offset: idtr=%lx\n", idtr);
> - fprintf(fp, "calc_kaslr_offset: cr3=%lx\n", cr3);
> + fprintf(fp, "calc_kaslr_offset: pgd=%lx\n", pgd);
> fprintf(fp, "calc_kaslr_offset: idtr(phys)=%lx\n",
> idtr_paddr);
> fprintf(fp, "calc_kaslr_offset:
> divide_error(vmlinux): %lx\n",
> st->divide_error_vmlinux);
> @@ -2084,9 +2090,12 @@ sadump_calc_kaslr_offset(ulong *kaslr_offset)
> * from vmcoreinfo
> */
> if (get_kaslr_offset_from_vmcoreinfo(
> - cr3, *kaslr_offset, &kaslr_offset_kdump,
> &phys_base_kdump)) {
> + *kaslr_offset, &kaslr_offset_kdump, &phys_base_kdump)) {
> *kaslr_offset = kaslr_offset_kdump;
> phys_base = phys_base_kdump;
> + } else if (CRASHDEBUG(1)) {
> + fprintf(fp, "sadump: failed to determine which kernel was
> running at crash,\n");
> + fprintf(fp, "sadump: asssuming the kdump 1st kernel.\n");
> }
>
> if (CRASHDEBUG(1)) {
> diff --git a/symbols.c b/symbols.c
> index 2372887..26b319a 100644
> --- a/symbols.c
> +++ b/symbols.c
> @@ -3072,10 +3072,14 @@ dump_symbol_table(void)
> fprintf(fp, "divide_error_vmlinux: %lx\n",
> st->divide_error_vmlinux);
> fprintf(fp, " idt_table_vmlinux: %lx\n",
> st->idt_table_vmlinux);
> fprintf(fp, "saved_command_line_vmlinux: %lx\n",
> st->saved_command_line_vmlinux);
> + fprintf(fp, " pti_init_vmlinux: %lx\n",
> st->pti_init_vmlinux);
> + fprintf(fp, " kaiser_init_vmlinux: %lx\n",
> st->kaiser_init_vmlinux);
> } else {
> fprintf(fp, "divide_error_vmlinux: (unused)\n");
> fprintf(fp, " idt_table_vmlinux: (unused)\n");
> fprintf(fp, "saved_command_line_vmlinux: (unused)\n");
> + fprintf(fp, " pti_init_vmlinux: (unused)\n");
> + fprintf(fp, " kaiser_init_vmlinux: (unused)\n");
> }
>
> fprintf(fp, " symval_hash[%d]: %lx\n", SYMVAL_HASH,
> @@ -12306,6 +12310,11 @@ numeric_forward(const void *P_x, const void *P_y)
> st->saved_command_line_vmlinux = valueof(x);
> else if (STREQ(y->name, "saved_command_line"))
> st->saved_command_line_vmlinux = valueof(y);
> +
> + if (STREQ(x->name, "pti_init"))
> + st->pti_init_vmlinux = valueof(x);
> + else if (STREQ(y->name, "kaiser_init"))
> + st->kaiser_init_vmlinux = valueof(y);
> }
>
> xs = bfd_get_section(x);
> --
> 1.8.3.1
It looks good to me. Thanks.
Dave, could you merge this patch?
Thanks.
HATAYAMA, Daisuke
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