[Crash-utility] [PATCH 2/2] arm64: make crash CONFIG_KASAN_HW_TAGS aware
vinayak menon
vinayakm.list at gmail.com
Tue Apr 27 13:47:20 UTC 2021
Hi Pingfan,
On Mon, Apr 26, 2021 at 8:06 PM piliu <piliu at redhat.com> wrote:
>
>
>
> On 4/26/21 7:17 PM, piliu wrote:
> >
> > Hi Vinayak,
> >
> > On 3/30/21 9:52 PM, Vinayak Menon wrote:
> >> With CONFIG_KASAN_HW_TAGS enabled kvaddr can be tagged
> >> and this results in readmem, vtop etc. fail like below.
> Sorry for the limited knowledge of this field. I have more question
> during the reviewing.
>
> -1.is this reproducible with SW TAGS?
> -2. HW TAGS aims for malloc, while here I see the handling LR, PC.
> It seems that they are more related to "Pointer Authentication"
I have not tried with SW tags. CONFIG_KASAN_HW_TAGS can be found here
in kernel https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/lib/Kconfig.kasan?h=v5.12#n102
The MTE based kasan is used for tagging malloc too. With
CONFIG_KASAN_HW_TAGS it is used to tag kernel memory, replacing the
regular kasan.
>
> Thanks,
> Pingfan
> >>
> >> "
> >> please wait... (gathering kmem slab cache data)
> >> crash: invalid kernel virtual address: f0ffff878000201c type:
> >> "kmem_cache objsize/object_size"
> >> crash: get_active_set: no tasks found?
> >> please wait... (gathering task table data)
> >> crash: invalid kernel virtual address: f1ffff87f51e3530 type:
> >> "xa_node shift"
> >> "
> >>
> >> Make the mask introduced for pointer authentication generic
> >> and use it in vtop and kvaddr validation.
> >>
> >> Signed-off-by: Vinayak Menon <vinayakm.list at gmail.com>
> >> ---
> >> arm64.c | 50 +++++++++++++++++++++++++++++++-------------------
> >> defs.h | 2 +-
> >> 2 files changed, 32 insertions(+), 20 deletions(-)
> >>
> >> diff --git a/arm64.c b/arm64.c
> >> index 5b59972..bb41cbb 100644
> >> --- a/arm64.c
> >> +++ b/arm64.c
> >> @@ -85,7 +85,8 @@ static int arm64_get_kvaddr_ranges(struct
> >> vaddr_range *);
> >> static void arm64_get_crash_notes(void);
> >> static void arm64_calc_VA_BITS(void);
> >> static int arm64_is_uvaddr(ulong, struct task_context *);
> >> -static void arm64_calc_KERNELPACMASK(void);
> >> +static int arm64_is_kvaddr(ulong);
> >> +static void arm64_calc_KERNELTAGMASK(void);
> >> /*
> >> @@ -215,7 +216,7 @@ arm64_init(int when)
> >> machdep->pagemask = ~((ulonglong)machdep->pageoffset);
> >> arm64_calc_VA_BITS();
> >> - arm64_calc_KERNELPACMASK();
> >> + arm64_calc_KERNELTAGMASK();
> >> ms = machdep->machspec;
> >> if (ms->VA_BITS_ACTUAL) {
> >> ms->page_offset = ARM64_PAGE_OFFSET_ACTUAL;
> >> @@ -228,7 +229,7 @@ arm64_init(int when)
> >> machdep->kvbase = ARM64_VA_START;
> >> ms->userspace_top = ARM64_USERSPACE_TOP;
> >> }
> >> - machdep->is_kvaddr = generic_is_kvaddr;
> >> + machdep->is_kvaddr = arm64_is_kvaddr;
> >> machdep->kvtop = arm64_kvtop;
> >> if (machdep->flags & NEW_VMEMMAP) {
> >> struct syment *sp;
> >> @@ -477,7 +478,7 @@ arm64_init(int when)
> >> case LOG_ONLY:
> >> machdep->machspec = &arm64_machine_specific;
> >> arm64_calc_VA_BITS();
> >> - arm64_calc_KERNELPACMASK();
> >> + arm64_calc_KERNELTAGMASK();
> >> arm64_calc_phys_offset();
> >> machdep->machspec->page_offset = ARM64_PAGE_OFFSET;
> >> arm64_calc_physvirt_offset();
> >> @@ -608,7 +609,7 @@ arm64_dump_machdep_table(ulong arg)
> >> fprintf(fp, " dis_filter: arm64_dis_filter()\n");
> >> fprintf(fp, " cmd_mach: arm64_cmd_mach()\n");
> >> fprintf(fp, " get_smp_cpus: arm64_get_smp_cpus()\n");
> >> - fprintf(fp, " is_kvaddr: generic_is_kvaddr()\n");
> >> + fprintf(fp, " is_kvaddr: arm64_is_kvaddr()\n");
> >> fprintf(fp, " is_uvaddr: arm64_is_uvaddr()\n");
> >> fprintf(fp, " value_to_symbol:
> >> generic_machdep_value_to_symbol()\n");
> >> fprintf(fp, " init_kernel_pgd: arm64_init_kernel_pgd\n");
> >> @@ -668,9 +669,9 @@ arm64_dump_machdep_table(ulong arg)
> >> fprintf(fp, "%ld\n", ms->VA_BITS_ACTUAL);
> >> else
> >> fprintf(fp, "(unused)\n");
> >> - fprintf(fp, "CONFIG_ARM64_KERNELPACMASK: ");
> >> - if (ms->CONFIG_ARM64_KERNELPACMASK)
> >> - fprintf(fp, "%lx\n", ms->CONFIG_ARM64_KERNELPACMASK);
> >> + fprintf(fp, "CONFIG_ARM64_KERNELTAGMASK: ");
> >> + if (ms->CONFIG_ARM64_KERNELTAGMASK)
> >> + fprintf(fp, "%lx\n", ms->CONFIG_ARM64_KERNELTAGMASK);
> >> else
> >> fprintf(fp, "(unused)\n");
> >> fprintf(fp, " userspace_top: %016lx\n", ms->userspace_top);
> >> @@ -1208,6 +1209,9 @@ arm64_kvtop(struct task_context *tc, ulong
> >> kvaddr, physaddr_t *paddr, int verbos
> >> if (!IS_KVADDR(kvaddr))
> >> return FALSE;
> >> + if (kvaddr & (1UL << 63))
> >> + kvaddr |= machdep->machspec->CONFIG_ARM64_KERNELTAGMASK;
> >> +
> >> if (!vt->vmalloc_start) {
> >> *paddr = VTOP(kvaddr);
> >> return TRUE;
> >> @@ -1828,7 +1832,7 @@ arm64_is_kernel_exception_frame(struct bt_info
> >> *bt, ulong stkptr)
> >> if (INSTACK(regs->sp, bt) && INSTACK(regs->regs[29], bt) &&
> >> !(regs->pstate & (0xffffffff00000000ULL | PSR_MODE32_BIT)) &&
> >> is_kernel_text(regs->pc) &&
> >> - is_kernel_text(regs->regs[30] |
> >> ms->CONFIG_ARM64_KERNELPACMASK)) {
> >> + is_kernel_text(regs->regs[30] |
> >> ms->CONFIG_ARM64_KERNELTAGMASK)) {
> >> switch (regs->pstate & PSR_MODE_MASK)
> >> {
> >> case PSR_MODE_EL1t:
> >> @@ -2198,8 +2202,8 @@ arm64_unwind_frame(struct bt_info *bt, struct
> >> arm64_stackframe *frame)
> >> frame->sp = fp + 0x10;
> >> frame->fp = GET_STACK_ULONG(fp);
> >> frame->pc = GET_STACK_ULONG(fp + 8);
> >> - if (is_kernel_text(frame->pc | ms->CONFIG_ARM64_KERNELPACMASK))
> >> - frame->pc |= ms->CONFIG_ARM64_KERNELPACMASK;
> >> + if (is_kernel_text(frame->pc | ms->CONFIG_ARM64_KERNELTAGMASK))
> >> + frame->pc |= ms->CONFIG_ARM64_KERNELTAGMASK;
> >> if ((frame->fp == 0) && (frame->pc == 0))
> >> return FALSE;
> >> @@ -2869,8 +2873,8 @@ arm64_print_text_symbols(struct bt_info *bt,
> >> struct arm64_stackframe *frame, FIL
> >> for (i = (start - bt->stackbase)/sizeof(ulong); i <
> >> LONGS_PER_STACK; i++) {
> >> up = (ulong *)(&bt->stackbuf[i*sizeof(ulong)]);
> >> val = *up;
> >> - if (is_kernel_text(val | ms->CONFIG_ARM64_KERNELPACMASK)) {
> >> - val |= ms->CONFIG_ARM64_KERNELPACMASK;
> >> + if (is_kernel_text(val | ms->CONFIG_ARM64_KERNELTAGMASK)) {
> >> + val |= ms->CONFIG_ARM64_KERNELTAGMASK;
> >> name = closest_symbol(val);
> >> fprintf(ofp, " %s[%s] %s at %lx",
> >> bt->flags & BT_ERROR_MASK ?
> >> @@ -3205,8 +3209,8 @@ arm64_print_exception_frame(struct bt_info *bt,
> >> ulong pt_regs, int mode, FILE *o
> >> rows = 4;
> >> } else {
> >> LR = regs->regs[30];
> >> - if (is_kernel_text (LR | ms->CONFIG_ARM64_KERNELPACMASK))
> >> - LR |= ms->CONFIG_ARM64_KERNELPACMASK;
> >> + if (is_kernel_text (LR | ms->CONFIG_ARM64_KERNELTAGMASK))
> >> + LR |= ms->CONFIG_ARM64_KERNELTAGMASK;
> >> SP = regs->sp;
> >> top_reg = 29;
> >> is_64_bit = TRUE;
> >> @@ -4102,6 +4106,14 @@ arm64_calc_virtual_memory_ranges(void)
> >> }
> >> static int
> >> +arm64_is_kvaddr(ulong addr)
> >> +{
> >> + if (addr & (1UL << 63))
> >> + addr |= machdep->machspec->CONFIG_ARM64_KERNELTAGMASK;
> >> + return generic_is_kvaddr(addr);
> >> +}
> >> +
> >> +static int
> >> arm64_is_uvaddr(ulong addr, struct task_context *tc)
> >> {
> >> return (addr < machdep->machspec->userspace_top);
> >> @@ -4129,21 +4141,21 @@ arm64_swp_offset(ulong pte)
> >> return pte;
> >> }
> >> -static void arm64_calc_KERNELPACMASK(void)
> >> +static void arm64_calc_KERNELTAGMASK(void)
> >> {
> >> ulong value = 0;
> >> char *string;
> >> - if ((string = pc->read_vmcoreinfo("NUMBER(KERNELPACMASK)"))) {
> >> + if ((string = pc->read_vmcoreinfo("NUMBER(KERNELTAGMASK)"))) {
> >
> > I git grep 5.12 kernel, but did not find this. Do you plan to do it in
> > kernel firstly?
> >
> > Thanks,
> > Pingfan
> >> value = htol(string, QUIET, NULL);
> >> free(string);
> >> } else if (machdep->machspec->tag_mask) {
> >> value = machdep->machspec->tag_mask;
> >> }
> >> - machdep->machspec->CONFIG_ARM64_KERNELPACMASK = value;
> >> + machdep->machspec->CONFIG_ARM64_KERNELTAGMASK = value;
> >> if (CRASHDEBUG(1))
> >> - fprintf(fp, "CONFIG_ARM64_KERNELPACMASK: %lx\n", value);
> >> + fprintf(fp, "CONFIG_ARM64_KERNELTAGMASK: %lx\n", value);
> >> }
> >> #endif /* ARM64 */
> >> diff --git a/defs.h b/defs.h
> >> index d406f5f..770c335 100644
> >> --- a/defs.h
> >> +++ b/defs.h
> >> @@ -3329,7 +3329,7 @@ struct machine_specific {
> >> ulong VA_BITS_ACTUAL;
> >> ulong CONFIG_ARM64_VA_BITS;
> >> ulong VA_START;
> >> - ulong CONFIG_ARM64_KERNELPACMASK;
> >> + ulong CONFIG_ARM64_KERNELTAGMASK;
> >> ulong physvirt_offset;
> >> ulong tag_mask;
> >> };
> >>
> >> --
> >> Crash-utility mailing list
> >> Crash-utility at redhat.com
> >> https://listman.redhat.com/mailman/listinfo/crash-utility
> >>
> >
> > --
> > Crash-utility mailing list
> > Crash-utility at redhat.com
> > https://listman.redhat.com/mailman/listinfo/crash-utility
>
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