A investigative hack that makes (for example) head -r356529 boot and operate normally an RPi4B (finally!): protect all armstub8-gic.bin's loaded content from replacement by the kernel
Mark Millard
marklmi at yahoo.com
Thu Feb 13 17:55:38 UTC 2020
On 2020-Feb-13, at 09:36, Mark Millard <marklmi at yahoo.com> wrote:
> On 2020-Feb-13, at 08:50, Mark Millard <marklmi at yahoo.com> wrote:
>
>> On 2020-Feb-13, at 07:22, Kyle Evans <kevans at freebsd.org> wrote:
>>
>>> On Thu, Feb 13, 2020 at 9:05 AM Ralf Wenk <iz-rpi03 at hs-karlsruhe.de> wrote:
>>>>
>>>> On 2020-02-13 at 15:26 +0100 Ralf Wenk wrote:
>>>>> On 2020-02-13 at 7:49 -0600 Kyle Evans wrote:
>>>>>> On Thu, Feb 13, 2020 at 7:43 AM Ralf Wenk <iz-rpi03 at hs-karlsruhe.de> wrote:
>>>>>>>
>>>>>>> On 2020-02-12 at 18:00 -0800 Mark Millard wrote via freebsd-arm:
>>>>>>>> [...]
>>>>>>>>
>>>>>>>> # svnlite diff /usr/src/sys/dev/fdt/fdt_common.c
>>>>>>>> Index: /usr/src/sys/dev/fdt/fdt_common.c
>>>>>>>> ===================================================================
>>>>>>>> --- /usr/src/sys/dev/fdt/fdt_common.c (revision 357529)
>>>>>>>> +++ /usr/src/sys/dev/fdt/fdt_common.c (working copy)
>>>>>>>> @@ -485,7 +485,18 @@
>>>>>>>>
>>>>>>>> tuples = res_len / tuple_size;
>>>>>>>> reservep = (pcell_t *)&reserve;
>>>>>>>> +#ifdef __aarch64__
>>>>>>>> + //HACK!!!
>>>>>>>> + // Reserve the first few pages, for example to
>>>>>>>> + // preserve armstub8-gic.bin or armstub.bin
>>>>>>>> + // content.
>>>>>>>> + mr[0].mr_start= 0;
>>>>>>>> + mr[0].mr_size= 2*4096;
>>>>>>>> + tuples++;
>>>>>>>> + for (i = 1; i < tuples; i++) {
>>>>>>>> +#else
>>>>>>>> for (i = 0; i < tuples; i++) {
>>>>>>>> +#endif
>>>>>>>>
>>>>>>>> rv = fdt_data_to_res(reservep, addr_cells, size_cells,
>>>>>>>> (u_long *)&mr[i].mr_start, (u_long *)&mr[i].mr_size);
>>>>>>>> @@ -512,6 +523,11 @@
>>>>>>>>
>>>>>>>> root = OF_finddevice("/reserved-memory");
>>>>>>>> if (root == -1) {
>>>>>>>> + // Fail over to checking for and handling memreserve,
>>>>>>>> + // such as for a RPi4B.
>>>>>>>> + if (0 == fdt_get_reserved_regions(reserved,mreserved))
>>>>>>>> + return (0);
>>>>>>>> +
>>>>>>>> return (ENXIO);
>>>>>>>> }
>>>>>>>>
>>>>>>>
>>>>>>> I can confirm that with your patch(es) my RPi3 does not freeze any more
>>>>>>> when loading mac_ntpd.ko. The patches are applied against r357853M.
>>>>
>>>> An reboot is working again too.
>>>>
>>>>>> Have you tested the RPi3 with just this second hunk of patch to
>>>>>> fallover to memreserve, or is the first hunk definitely required as
>>>>>> well?
>>>>>
>>>>> Good question. I tested both hunks together.
>>>>> Will try what happens when just applying the second and report back.
>>>>
>>>> Here it is:
>>>> Without the first hunk the system freezes again when loading mac_ntpd.ko.
>>>> Also the CPU information during boot for CPUs 1 to 3 looks strange again.
>>>>
>>>
>>> Yeah- I see it now; both armstubs are about 5k. I've raised an
>>> issue[0] with upstream for armstub/rpi bits to work out the proper
>>> solution, because I don't necessarily want to commit the workaround.
>>> I'll throw up the second hunk on phabricator for review by #arm/#arm64
>>> folks, because that seems to me the proper fallback.
>>>
>>> I also discovered some issues when trying to read /memreserve/ with
>>> our dtc and filed a PR[1] to fix those.
>>>
>>> Thanks,
>>>
>>> Kyle Evans
>>>
>>> [0] https://github.com/raspberrypi/tools/issues/107
>>> [1] https://github.com/davidchisnall/dtc/pull/59
>>
>> The DTB information below is from:
>>
>> U-Boot> fdt addr 0x7ef2000
>> U-Boot> fdt print /
>>
>> on a RPi4B 4 GiByte.
>>
>> On at least the RPi4B memreserve is not what causes
>> the first page to be excluded:
>>
>> memreserve = <0x3b400000 0x04c00000>;
>>
>> Nor is memory at 0 the cause:
>>
>> memory at 0 {
>> device_type = "memory";
>> reg = <0x00000000 0x00000000 0x3b400000 0x00000000 0x40000000 0xbc000000>;
>> };
>>
>> (That also skips the memreserve area.)
>>
>> I do not find anything in the DTB that indicates
>> to exclude the first page.
>>
>> My hypothesis is that the FreeBSD code excludes
>> the page based on some less obvious relationship
>> that I'm not identifying.
>>
>> There is the cpu-rlease-addr information that seems
>> to refer to some 1st memory page content:
>>
>> cpus {
>> #address-cells = <0x00000001>;
>> #size-cells = <0x00000000>;
>> enable-method = "brcm,bcm2836-smp";
>> phandle = <0x000000be>;
>> cpu at 0 {
>> device_type = "cpu";
>> compatible = "arm,cortex-a72";
>> reg = <0x00000000>;
>> enable-method = "spin-table";
>> cpu-release-addr = <0x00000000 0x000000d8>;
>> phandle = <0x0000001d>;
>> };
>> cpu at 1 {
>> device_type = "cpu";
>> compatible = "arm,cortex-a72";
>> reg = <0x00000001>;
>> enable-method = "spin-table";
>> cpu-release-addr = <0x00000000 0x000000e0>;
>> phandle = <0x0000001e>;
>> };
>> cpu at 2 {
>> device_type = "cpu";
>> compatible = "arm,cortex-a72";
>> reg = <0x00000002>;
>> enable-method = "spin-table";
>> cpu-release-addr = <0x00000000 0x000000e8>;
>> phandle = <0x0000001f>;
>> };
>> cpu at 3 {
>> device_type = "cpu";
>> compatible = "arm,cortex-a72";
>> reg = <0x00000003>;
>> enable-method = "spin-table";
>> cpu-release-addr = <0x00000000 0x000000f0>;
>> phandle = <0x00000020>;
>> };
>> };
>
>
>
>
> Looking at the code there is:
>
> /* Load the physical memory ranges */
> efihdr = (struct efi_map_header *)preload_search_info(kmdp,
> MODINFO_METADATA | MODINFOMD_EFI_MAP);
> if (efihdr != NULL)
> add_efi_map_entries(efihdr);
> #ifdef FDT
> else {
> /* Grab physical memory regions information from device tree. */
> if (fdt_get_mem_regions(mem_regions, &mem_regions_sz,
> NULL) != 0)
> panic("Cannot get physical memory regions");
> arm_physmem_hardware_regions(mem_regions, mem_regions_sz);
> }
> if (fdt_get_reserved_mem(mem_regions, &mem_regions_sz) == 0)
> arm_physmem_exclude_regions(mem_regions, mem_regions_sz,
> EXFLAG_NODUMP | EXFLAG_NOALLOC);
> #endif
>
> /* Exclude the EFI framebuffer from our view of physical memory. */
> efifb = (struct efi_fb *)preload_search_info(kmdp,
> MODINFO_METADATA | MODINFOMD_EFI_FB);
> if (efifb != NULL)
> arm_physmem_exclude_region(efifb->fb_addr, efifb->fb_size,
> EXFLAG_NOALLOC);
> . . .
> if (boothowto & RB_VERBOSE) {
> print_efi_map_entries(efihdr);
> arm_physmem_print_tables();
> }
>
>
> It looks to me like the boot -v text:
>
> Type Physical Virtual #Pages Attr
> Reserved 000000000000 0 00000001 WB
> ConventionalMemory 000000001000 1000 00007ef1 WB
> BootServicesData 000007ef2000 7ef2000 0000001c WB
> ConventionalMemory 000007f0e000 7f0e000 00029f93 WB
> BootServicesData 000031ea1000 31ea1000 00000001 WB
> LoaderData 000031ea2000 31ea2000 00008001 WB
> LoaderCode 000039ea3000 39ea3000 000000a6 WB
> Reserved 000039f49000 39f49000 00000007 WB
> BootServicesData 000039f50000 39f50000 00000001 WB
> Reserved 000039f51000 39f51000 00000002 WB
> RuntimeServicesData 000039f53000 39f53000 00000001 WB RUNTIME
> Reserved 000039f54000 39f54000 00000001 WB
> BootServicesData 000039f55000 39f55000 00000002 WB
> RuntimeServicesData 000039f57000 39f57000 00000001 WB RUNTIME
> LoaderData 000039f58000 39f58000 00001408 WB
> RuntimeServicesCode 00003b360000 3b360000 00000010 WB RUNTIME
> LoaderData 00003b370000 3b370000 00000090 WB
> BootServicesData 000040000000 40000000 000bc000 WB
> MemoryMappedIO 0000fe100000 fe100000 00000001 RUNTIME
>
> is from print_efi_map_entries via the efihdr instead
> of from the FreeBSD FDT code and the DTB.
>
> So is it u-boot that provides the efihdr for which
> add_efi_map_entries generated those regions?
>
> That might explain why I do not find matching DTB
> material for all of it.
Looks like the efi memory map traces back to the loader
and its use of GetMemoryMap (as far as FreeBSD goes):
# grep -r "GetMemoryMap" /usr/src/sys/ | more
/usr/src/sys/amd64/amd64/machdep.c: * Memory map data provided by UEFI via the GetMemoryMap
/usr/src/sys/arm64/arm64/machdep.c: * Memory map data provided by UEFI via the GetMemoryMap
/usr/src/sys/arm/arm/machdep_boot.c: * Memory map data provided by UEFI via the GetMemoryMap
/usr/src/sys/contrib/edk2/Include/Uefi/UefiSpec.h: EFI_GET_MEMORY_MAP GetMemoryMap;
# grep -r "GetMemoryMap" /usr/src/stand/ | more
/usr/src/stand/efi/loader/copy.c: status = BS->GetMemoryMap(&sz, map, &key, &dsz, &dver);
/usr/src/stand/efi/loader/main.c: status = BS->GetMemoryMap(&sz, 0, &key, &dsz, &dver);
/usr/src/stand/efi/loader/main.c: status = BS->GetMemoryMap(&sz, map, &key, &dsz, &dver);
/usr/src/stand/efi/loader/bootinfo.c: status = BS->GetMemoryMap(&sz, mm, &efi_mapkey, &dsz, &mmver);
/usr/src/stand/efi/loader/bootinfo.c: printf("%s: GetMemoryMap error %lu\n", __func__,
/usr/src/stand/efi/include/efiapi.h: EFI_GET_MEMORY_MAP GetMemoryMap;
===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
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