Re: [Xen-devel] [PATCH v2 for-4.9 0/5] xen/arm: Properly map the FDT in the boot page table

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

I committed this series, thank you.

On Thu, 20 Apr 2017, Julien Grall wrote:
> Hi,
> 
> Whilst doing some testing on Juno using GRUB, I noticed random early crash
> depending ([1]) on the binaries I was using.
> 
> This is because Xen is assuming that the FDT will always fit in a 2MB
> superpage whilst the boot documentation allow the FDT to cross a 2MB boundary.
> 
> The first patch move the code that map the FDT in the boot page table from
> assembly to C making easier to modify the code.
> 
> This series is candidate for Xen 4.9. Whilst this early boot rework sounds
> scary, a user can see random early crash without this series. I chose
> to move all the FDT mapping code in C right now because it is less error-prone
> to write C code than assembly.
> 
> I have tested both ARM32 and ARM64 with different position of the FDT without
> noticing any issue.
> 
> For all the changes see in each patches.
> 
> Cheers,
> 
> [1]
> 
> (XEN) Hypervisor Trap. HSR=0x96000006 EC=0x25 IL=1 Syndrome=0x6
> (XEN) CPU0: Unexpected Trap: Hypervisor
> (XEN) ----[ Xen-4.9-unstable  arm64  debug=y   Not tainted ]----
> (XEN) CPU:    0
> (XEN) PC:     0000000000264140 strlen+0x10/0x84
> (XEN) LR:     00000000002401c0
> (XEN) SP:     00000000002cfc20
> (XEN) CPSR:   400003c9 MODE:64-bit EL2h (Hypervisor, handler)
> (XEN)      X0: 0000000000801230  X1: 0000000000801230  X2: 0000000000005230
> (XEN)      X3: 0000000000000030  X4: 0000000000000030  X5: 0000000000000038
> (XEN)      X6: 0000000000000034  X7: 0000000000000000  X8: 7f7f7f7f7f7f7f7f
> (XEN)      X9: 64622c6479687222 X10: 7f7f7f7f7f7f7f7f X11: 0101010101010101
> (XEN)     X12: 0000000000000030 X13: ffffff00ff000000 X14: 0800000003000000
> (XEN)     X15: ffffffffffffffff X16: 00000000fefff610 X17: 00000000000000f0
> (XEN)     X18: 0000000000000004 X19: 0000000000000008 X20: 00000000007fc040
> (XEN)     X21: 00000000007fc000 X22: 000000000000000e X23: 0000000000000000
> (XEN)     X24: 00000000002a9f58 X25: 0000000000801230 X26: 00000000002a9f68
> (XEN)     X27: 00000000002a9f58 X28: 0000000000298910  FP: 00000000002cfc20
> (XEN)
> (XEN)   VTCR_EL2: 80010c40
> (XEN)  VTTBR_EL2: 0000082800203000
> (XEN)
> (XEN)  SCTLR_EL2: 30c5183d
> (XEN)    HCR_EL2: 000000000038663f
> (XEN)  TTBR0_EL2: 00000000f4912000
> (XEN)
> (XEN)    ESR_EL2: 96000006
> (XEN)  HPFAR_EL2: 00000000e8071000
> (XEN)    FAR_EL2: 0000000000801230
> (XEN)
> (XEN) Xen stack trace from sp=00000000002cfc20:
> (XEN)    00000000002cfc70 0000000000240254 00000000002a9f58 00000000007fc000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 00000000007fc03c
> (XEN)    00000000002cfd78 0000000000000000 00000000002cfca0 00000000002986fc
> (XEN)    0000000000000000 00000000007fc000 0000000000000000 0000000000000000
> (XEN)    00000000002cfcc0 0000000000298f1c 0000000000000000 00000000007fc000
> (XEN)    00000000002cfdc0 000000000029904c 00000000f47fc000 00000000f4604000
> (XEN)    00000000f47fc000 00000000007fc000 0000000000400000 0000000000000100
> (XEN)    00000000f4604000 0000000000000001 0000000000000001 8000000000000002
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 00000000002cfdc0 0000000000299038
> (XEN)    00000000f47fc000 00000000f4604000 00000000f47fc000 0000000000000000
> (XEN)    00000000002cfe20 000000000029c420 00000000002d8000 00000000f4604000
> (XEN)    00000000f47fc000 0000000000000000 0000000000400000 0000000000000100
> (XEN)    00000000f4604000 0000000000000001 00000000f47fc000 000000000029c404
> (XEN)    00000000fefff510 0000000000200624 00000000f4804000 00000000f4604000
> (XEN)    00000000f47fc000 0000000000000000 0000000000400000 0000000000000100
> (XEN)    0000000000000001 0000000000000001 0000000000000001 8000000000000002
> (XEN)    00000000f47fc000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN)    0000000000000000 0000000000000000 0000000000000000 0000000000000000
> (XEN) Xen call trace:
> (XEN)    [<0000000000264140>] strlen+0x10/0x84 (PC)
> (XEN)    [<00000000002401c0>] fdt_get_property_namelen+0x9c/0xf0 (LR)
> (XEN)    [<0000000000240254>] fdt_get_property+0x40/0x50
> (XEN)    [<00000000002986fc>] bootfdt.c#device_tree_get_u32+0x18/0x5c
> (XEN)    [<0000000000298f1c>] device_tree_for_each_node+0x84/0x144
> (XEN)    [<000000000029904c>] boot_fdt_info+0x70/0x23c
> (XEN)    [<000000000029c420>] start_xen+0x9c/0xd30
> (XEN)    [<0000000000200624>] arm64/head.o#paging+0x84/0xbc
> (XEN)
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 0:
> (XEN) CPU0: Unexpected Trap: Hypervisor
> (XEN)
> (XEN) ****************************************
> 
> Julien Grall (5):
>   xen/arm: Add BOOT_FDT_VIRT_END and BOOT_FDT_SLOT_SIZE
>   xen/arm: mm: Move create_mappings function earlier in the file
>   xen/arm: Move the code to map FDT in the boot tables from assembly to
>     C
>   xen/arm: Check if the FDT passed by the bootloader is valid
>   xen/arm: Properly map the FDT in the boot page table
> 
>  xen/arch/arm/arm32/head.S    |  14 -----
>  xen/arch/arm/arm64/head.S    |  13 -----
>  xen/arch/arm/mm.c            | 123 
> +++++++++++++++++++++++++++++++------------
>  xen/arch/arm/setup.c         |  10 ++--
>  xen/include/asm-arm/config.h |  16 +++---
>  xen/include/asm-arm/mm.h     |   2 +
>  xen/include/asm-arm/setup.h  |   3 ++
>  7 files changed, 110 insertions(+), 71 deletions(-)
> 
> -- 
> 2.11.0
> 

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