Fatal trap 12: page fault on Acer Chromebook 720 (peppy)
Michael Gmelin
freebsd at grem.de
Wed Aug 22 22:10:38 UTC 2018
> On 22. Aug 2018, at 23:15, Konstantin Belousov <kostikbel at gmail.com> wrote:
>
>> On Wed, Aug 22, 2018 at 10:03:54PM +0200, Michael Gmelin wrote:
>>
>>
>>>> On 22. Aug 2018, at 17:46, Konstantin Belousov <kostikbel at gmail.com> wrote:
>>>>
>>>> On Tue, Aug 21, 2018 at 12:14:35AM +0200, Michael Gmelin wrote:
>>>>
>>>>
>>>>>> On 20. Aug 2018, at 17:09, Konstantin Belousov <kostikbel at gmail.com> wrote:
>>>>>>
>>>>>> On Mon, Aug 20, 2018 at 12:45:12AM +0200, Michael Gmelin wrote:
>>>>>>
>>>>>> See here for a screenshot (also including the output of "show pte
>>>>>> 0xfffff80001000000"):
>>>>>>
>>>>>> https://gist.github.com/grembo/78d0f2a100dd4f16775b85a118769658#file-ddb1-png
>>>>> It is too early for ddb routines to register.
>>>>> Ok can you try the following debugging patch, to verify my guess ?
>>>>>
>>>>> diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
>>>>> index 18777d23f09..cd05fdb763f 100644
>>>>> --- a/sys/amd64/amd64/pmap.c
>>>>> +++ b/sys/amd64/amd64/pmap.c
>>>>> @@ -1052,8 +1052,7 @@ create_pagetables(vm_paddr_t *firstaddr)
>>>>> pd_p = (pd_entry_t *)DMPDkernphys;
>>>>> for (i = 0; i < (NPDEPG * nkdmpde); i++)
>>>>> pd_p[i] = (i << PDRSHIFT) | X86_PG_V | PG_PS | pg_g |
>>>>> - X86_PG_M | X86_PG_A | pg_nx |
>>>>> - bootaddr_rwx(i << PDRSHIFT);
>>>>> + X86_PG_M | X86_PG_A | pg_nx | X86_PG_RW;
>>>>> for (i = 0; i < nkdmpde; i++)
>>>>> pdp_p[i] = (DMPDkernphys + ptoa(i)) | X86_PG_RW |
>>>>> X86_PG_V;
>>>>
>>>> With this change it boots okay (mptramp_pagetables is 0x1000000, as expected).
>>>
>>> Can you apply the following on top of the previous debugging patch and show
>>> me the line printed ?
>>>
>>> diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
>>> index 3d70532b7fd..613fa9f2165 100644
>>> --- a/sys/amd64/amd64/pmap.c
>>> +++ b/sys/amd64/amd64/pmap.c
>>> @@ -2662,6 +2662,7 @@ pmap_pinit0(pmap_t pmap)
>>> pmap->pm_pcids[i].pm_gen = 1;
>>> }
>>> pmap_activate_boot(pmap);
>>> +printf("bootaddr addr %#lx rwx %#lx btext %#lx _end %#lx brwsection %#lx etext %#lx KERNBASE %#lx\n", 0x1000000UL, bootaddr_rwx(0x1000000UL), (uintptr_t)btext, (uintptr_t)_end, (uintptr_t)brwsection, (uintptr_t)etext, (uintptr_t)KERNBASE);
>>> }
>>>
>>> void
>>
>> bootaddr addr 0x1000000 rwx 0 btext 0xffffffff80342000 _end 0xffffffff823cf840 brwsection #ffffffff81a00000 etext 0xffffffff812041e4 KERNBASE 0xffffffff80000000
>>
>
> Try this, please. Revert all debugging pmap.c patches that I provided
> before.
>
> diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c
> index 4ca2e07e578..2ee8f862854 100644
> --- a/sys/amd64/amd64/mp_machdep.c
> +++ b/sys/amd64/amd64/mp_machdep.c
> @@ -87,6 +87,8 @@ __FBSDID("$FreeBSD$");
>
> #define GiB(v) (v ## ULL << 30)
>
> +#define AP_BOOTPT_SZ (PAGE_SIZE * 3)
> +
> extern struct pcpu __pcpu[];
>
> /* Temporary variables for init_secondary() */
> @@ -101,45 +103,78 @@ char *dbg_stack;
>
> static int start_ap(int apic_id);
>
> +static bool
> +is_kernel_paddr(vm_paddr_t pa)
> +{
> +
> + return (pa >= trunc_2mpage(btext - KERNBASE) &&
> + pa < round_page(_end - KERNBASE));
> +}
> +
> +static bool
> +is_mpboot_good(vm_paddr_t start, vm_paddr_t end)
> +{
> +
> + return (start + AP_BOOTPT_SZ <= GiB(4) &&
> + end >= start + AP_BOOTPT_SZ && atop(end) < Maxmem);
> +}
> +
> /*
> * Calculate usable address in base memory for AP trampoline code.
> */
> void
> mp_bootaddress(vm_paddr_t *physmap, unsigned int *physmap_idx)
> {
> + vm_paddr_t start, end;
> unsigned int i;
> bool allocated;
>
> alloc_ap_trampoline(physmap, physmap_idx);
>
> + /*
> + * Find a memory region big enough below the 4GB boundary to
> + * store the initial page tables. Region must be mapped by
> + * the direct map.
> + *
> + * Note that it needs to be aligned to a page boundary.
> + */
> allocated = false;
> for (i = *physmap_idx; i <= *physmap_idx; i -= 2) {
> /*
> - * Find a memory region big enough below the 4GB
> - * boundary to store the initial page tables. Region
> - * must be mapped by the direct map.
> - *
> - * Note that it needs to be aligned to a page
> - * boundary.
> + * First, try to chomp at the start of the physmap region.
> + * Kernel binary might claim it already.
> + */
> + start = round_page(physmap[i]);
> + end = trunc_page(physmap[i + 1]);
> + if (is_mpboot_good(start, end) &&
> + !is_kernel_paddr(start) && !is_kernel_paddr(end - 1)) {
> + allocated = true;
> + physmap[i] = start + AP_BOOTPT_SZ;
> + break;
> + }
> +
> + /*
> + * Second, try to chomp at the end. Again, check
> + * against kernel.
> */
> - if (physmap[i] >= GiB(4) || physmap[i + 1] -
> - round_page(physmap[i]) < PAGE_SIZE * 3 ||
> - atop(physmap[i + 1]) > Maxmem)
> - continue;
> -
> - allocated = true;
> - mptramp_pagetables = round_page(physmap[i]);
> - physmap[i] = round_page(physmap[i]) + (PAGE_SIZE * 3);
> + end = trunc_page(physmap[i + 1]);
> + start = end - AP_BOOTPT_SZ;
> + if (start >= physmap[i] && is_mpboot_good(start, end) &&
> + !is_kernel_paddr(start) && !is_kernel_paddr(end - 1)) {
> + allocated = true;
> + physmap[i + 1] = start;
> + break;
> + }
> + }
> + if (allocated) {
> + mptramp_pagetables = start;
> if (physmap[i] == physmap[i + 1] && *physmap_idx != 0) {
> memmove(&physmap[i], &physmap[i + 2],
> sizeof(*physmap) * (*physmap_idx - i + 2));
> *physmap_idx -= 2;
> }
> - break;
> - }
> -
> - if (!allocated) {
> - mptramp_pagetables = trunc_page(boot_address) - (PAGE_SIZE * 3);
> + } else {
> + mptramp_pagetables = trunc_page(boot_address) - AP_BOOTPT_SZ;
> if (bootverbose)
> printf(
> "Cannot find enough space for the initial AP page tables, placing them at %#x",
Reverted back to r337813 and applied the patch. Unfortunately it panics just like before. Adding back physmap debugging like before shows that it’s still using pages 0x1000-0x1003 (Stopped at native_start_all_aps+0x92: movq %rax,(%rsi))
Best,
Michael
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