Re: Fatal trap 12: page fault on Acer Chromebook 720 (peppy)

From: Konstantin Belousov <kostikbel_at_gmail.com>
Date: Fri, 24 Aug 2018 22:59:47 +0300
On Thu, Aug 23, 2018 at 12:10:34AM +0200, Michael Gmelin wrote:
> 
> 
> > 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
> >>>>> _at__at_ -1052,8 +1052,7 _at__at_ 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
> >>> _at__at_ -2662,6 +2662,7 _at__at_ 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
> > _at__at_ -87,6 +87,8 _at__at_ __FBSDID("$FreeBSD$");
> > 
> > #define GiB(v)            (v ## ULL << 30)
> > 
> > +#define    AP_BOOTPT_SZ        (PAGE_SIZE * 3)
> > +
> > extern    struct pcpu __pcpu[];
> > 
> > /* Temporary variables for init_secondary()  */
> > _at__at_ -101,45 +103,78 _at__at_ 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))
> 

Please apply the following debugging patch on top of the previous 'fix'.
You need debug.late_console=0.

diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c
index 2ee8f862854..1a14b1800b1 100644
--- a/sys/amd64/amd64/mp_machdep.c
+++ b/sys/amd64/amd64/mp_machdep.c
_at__at_ -130,7 +130,7 _at__at_ mp_bootaddress(vm_paddr_t *physmap, unsigned int *physmap_idx)
 	bool allocated;
 
 	alloc_ap_trampoline(physmap, physmap_idx);
-
+printf("btext %#lx _end %#lx brwsection %#lx etext %#lx KERNBASE %#lx\n", (uintptr_t)btext, (uintptr_t)_end, (uintptr_t)brwsection, (uintptr_t)etext, (uintptr_t)KERNBASE);
 	/*
 	 * Find a memory region big enough below the 4GB boundary to
 	 * store the initial page tables.  Region must be mapped by
_at__at_ -146,10 +146,13 _at__at_ mp_bootaddress(vm_paddr_t *physmap, unsigned int *physmap_idx)
 		 */
 		start = round_page(physmap[i]);
 		end = trunc_page(physmap[i + 1]);
+printf("physmap[%d] %#lx physmap[%d] %#lx\n", i, physmap[i], i + 1, physmap[i + 1]);
+printf("start %#lx end %#lx is_mpboot_good %d is_kernel_paddr(start) %d is_kernel_paddr(end - 1) %d\n", start, end, is_mpboot_good(start, end), is_kernel_paddr(start), is_kernel_paddr(end - 1));
 		if (is_mpboot_good(start, end) &&
 		    !is_kernel_paddr(start) && !is_kernel_paddr(end - 1)) {
 			allocated = true;
 			physmap[i] = start + AP_BOOTPT_SZ;
+printf("allocated\n");
 			break;
 		}
 
_at__at_ -159,10 +162,12 _at__at_ mp_bootaddress(vm_paddr_t *physmap, unsigned int *physmap_idx)
 		 */
 		end = trunc_page(physmap[i + 1]);
 		start = end - AP_BOOTPT_SZ;
+printf("start %#lx end %#lx is_mpboot_good %d is_kernel_paddr(start) %d is_kernel_paddr(end - 1) %d\n", start, end, is_mpboot_good(start, end), is_kernel_paddr(start), is_kernel_paddr(end - 1));
 		if (start >= physmap[i] && is_mpboot_good(start, end) &&
 		    !is_kernel_paddr(start) && !is_kernel_paddr(end - 1)) {
 			allocated = true;
 			physmap[i + 1] = start;
+printf("allocated\n");
 			break;
 		}
 	}
Received on Fri Aug 24 2018 - 17:59:59 UTC

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