[Xen-devel] [PATCH for-4.9 0/4] xen/arm: Properly map the FDT in the boot page table

[Julien Grall <julien.grall@xxxxxxx>]

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.

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 (4):
  xen/arm: Add BOOT_FDT_VIRT_END and BOOT_FDT_SLOT_SIZE
  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            | 61 +++++++++++++++++++++++++++++++++++++++++++-
 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, 82 insertions(+), 37 deletions(-)

-- 
2.11.0


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