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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH for-4.9 4/4] xen/arm: Properly map the FDT in the boot page table
On Wed, 19 Apr 2017, Julien Grall wrote:
> Currently, Xen is assuming the FDT will always fit in a 2MB section.
> Recently, I noticed an early crash on Xen when using GRUB with the
> following call trace:
>
> (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) ****************************************
>
> Indeed, the booting documentation for AArch32 and AArch64 only requires
> the FDT to be placed on a 8-byte boundary. This means the Device-Tree can
> cross a 2MB boundary.
>
> Given that Xen limits the size of the FDT to 2MB, it will always fit in
> a 4MB slot. So extend the fixmap slot for FDT from 2MB to 4MB.
>
> The second 2MB superpage will only be mapped if the FDT is cross the 2MB
> boundary.
>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> ---
> xen/arch/arm/mm.c | 16 ++++++++++++++--
> xen/include/asm-arm/config.h | 14 +++++++-------
> 2 files changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 53d36e2ce2..9cff1619c6 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -451,6 +451,7 @@ void * __init early_fdt_map(paddr_t fdt_paddr)
> paddr_t base_paddr = fdt_paddr & SECOND_MASK;
> paddr_t offset;
> void *fdt_virt;
> + uint32_t size;
>
> /*
> * Check whether the physical FDT address is set and meets the minimum
> @@ -475,9 +476,17 @@ void * __init early_fdt_map(paddr_t fdt_paddr)
> if ( fdt_magic(fdt_virt) != FDT_MAGIC )
> return NULL;
>
> - if ( fdt_totalsize(fdt_virt) > MAX_FDT_SIZE )
> + size = fdt_totalsize(fdt_virt);
> + if ( size > MAX_FDT_SIZE )
> return NULL;
>
> + if ( (offset + size) > SZ_2M )
> + {
> + create_mappings(boot_second, BOOT_FDT_VIRT_START + SZ_2M,
> + paddr_to_pfn(base_paddr + SZ_2M),
> + SZ_2M >> PAGE_SHIFT, SZ_2M);
> + }
> +
> return fdt_virt;
> }
>
> @@ -485,7 +494,8 @@ void __init remove_early_mappings(void)
> {
> lpae_t pte = {0};
> write_pte(xen_second + second_table_offset(BOOT_FDT_VIRT_START), pte);
> - flush_xen_data_tlb_range_va(BOOT_FDT_VIRT_START, SECOND_SIZE);
> + write_pte(xen_second + second_table_offset(BOOT_FDT_VIRT_START), pte);
Aren't you writing the same pte twice at the same address?
> + flush_xen_data_tlb_range_va(BOOT_FDT_VIRT_START, BOOT_FDT_SLOT_SIZE);
> }
>
> extern void relocate_xen(uint64_t ttbr, void *src, void *dst, size_t len);
> @@ -544,6 +554,8 @@ void __init setup_pagetables(unsigned long
> boot_phys_offset, paddr_t xen_paddr)
> /* ... DTB */
> pte = boot_second[second_table_offset(BOOT_FDT_VIRT_START)];
> xen_second[second_table_offset(BOOT_FDT_VIRT_START)] = pte;
> + pte = boot_second[second_table_offset(BOOT_FDT_VIRT_START + SZ_2M)];
> + xen_second[second_table_offset(BOOT_FDT_VIRT_START + SZ_2M)] = pte;
>
> /* ... Boot Misc area for xen relocation */
> dest_va = BOOT_RELOC_VIRT_START;
> diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
> index 9c14a385e7..5b6f3c985d 100644
> --- a/xen/include/asm-arm/config.h
> +++ b/xen/include/asm-arm/config.h
> @@ -77,12 +77,12 @@
> * 0 - 2M Unmapped
> * 2M - 4M Xen text, data, bss
> * 4M - 6M Fixmap: special-purpose 4K mapping slots
> - * 6M - 8M Early boot mapping of FDT
> - * 8M - 10M Early relocation address (used when relocating Xen)
> + * 6M - 10M Early boot mapping of FDT
> + * 10M - 12M Early relocation address (used when relocating Xen)
> * and later for livepatch vmap (if compiled in)
> *
> * ARM32 layout:
> - * 0 - 10M <COMMON>
> + * 0 - 12M <COMMON>
> *
> * 32M - 128M Frametable: 24 bytes per page for 16GB of RAM
> * 256M - 1G VMAP: ioremap and early_ioremap use this virtual address
> @@ -93,7 +93,7 @@
> *
> * ARM64 layout:
> * 0x0000000000000000 - 0x0000007fffffffff (512GB, L0 slot [0])
> - * 0 - 10M <COMMON>
> + * 0 - 12M <COMMON>
> *
> * 1G - 2G VMAP: ioremap and early_ioremap
> *
> @@ -113,12 +113,12 @@
> #define FIXMAP_ADDR(n) (_AT(vaddr_t,0x00400000) + (n) * PAGE_SIZE)
>
> #define BOOT_FDT_VIRT_START _AT(vaddr_t,0x00600000)
> -#define BOOT_FDT_SLOT_SIZE MB(2)
> +#define BOOT_FDT_SLOT_SIZE MB(4)
> #define BOOT_FDT_VIRT_END (BOOT_FDT_VIRT_START + BOOT_FDT_SLOT_SIZE)
>
> -#define BOOT_RELOC_VIRT_START _AT(vaddr_t,0x00800000)
> +#define BOOT_RELOC_VIRT_START _AT(vaddr_t,0x00a00000)
Wouldn't it be better to define it as BOOT_FDT_VIRT_END?
> #ifdef CONFIG_LIVEPATCH
> -#define LIVEPATCH_VMAP_START _AT(vaddr_t,0x00800000)
> +#define LIVEPATCH_VMAP_START _AT(vaddr_t,0x00a00000)
same here
> #define LIVEPATCH_VMAP_END (LIVEPATCH_VMAP_START + MB(2))
> #endif
>
> --
> 2.11.0
>
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