Re: [PATCH] Revert "arm64: vmemmap: use virtual projection of linear region"

[Laura Abbott]

On 03/08/2016 11:03 AM, David Daney wrote:
> From: David Daney <david.daney@xxxxxxxxxx>
>
> This reverts commit dfd55ad85e4a7fbaa82df12467515ac3c81e8a3e.
>
> Commit dfd55ad85e4a ("arm64: vmemmap: use virtual projection of linear
> region") causes this failure on Cavium Thunder systems:
>
> EFI stub: Booting Linux Kernel...
> EFI stub: Using DTB from configuration table
> EFI stub: Exiting boot services and installing virtual address map...
> [    0.000000] Booting Linux on physical CPU 0x0
> [    0.000000] Linux version 4.5.0-rc7-numa+ (ddaney@xxxxxxxxxxxxxxxxxxxxx) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-4) (GCC) ) #125 SMP PREEMPT Tue Mar 8 09:59:40 PST 2016
> [    0.000000] Boot CPU: AArch64 Processor [431f0a10]
> [    0.000000] earlycon: Early serial console at MMIO 0x87e024000000 (options '')
> [    0.000000] bootconsole [uart0] enabled
> [    0.000000] efi: Getting EFI parameters from FDT:
> [    0.000000] EFI v2.40 by Cavium Thunder cn88xx EFI jenkins_weekly_build_6-1-g188619c-dirty Feb 19 2016 13:32:48
> [    0.000000] efi:  ACPI=0xfffff000  ACPI 2.0=0xfffff014  SMBIOS 3.0=0x3faa62000
> [    0.000000] Unable to handle kernel paging request at virtual address fffffdff60ff0000
> [    0.000000] pgd = fffffe0000df0000
> [    0.000000] [fffffdff60ff0000] *pgd=00000003ffda0003, *pud=00000003ffda0003, *pmd=00000003ffda0003, *pte=0000000000000000
> [    0.000000] Internal error: Oops: 96000007 [#1] PREEMPT SMP
> [    0.000000] Modules linked in:
> [    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.5.0-rc7-numa+ #125
> [    0.000000] Hardware name: Cavium ThunderX CN88XX board (DT)
> [    0.000000] task: fffffe0000b29800 ti: fffffe0000af0000 task.ti: fffffe0000af0000
> [    0.000000] PC is at memmap_init_zone+0xd4/0x11c
> [    0.000000] LR is at memmap_init_zone+0xb4/0x11c
> [    0.000000] pc : [<fffffe0000a73c94>] lr : [<fffffe0000a73c74>] pstate: 800002c5
> [    0.000000] sp : fffffe0000af3d50
> [    0.000000] x29: fffffe0000af3d50 x28: 0000000000000001
> [    0.000000] x27: fffffe000092c2c0 x26: fffffe0000a90fc0
> [    0.000000] x25: fffffe0000b20000 x24: 0000000000040000
> [    0.000000] x23: 0000000000000000 x22: 4000000000000000
> [    0.000000] x21: 0000000000000001 x20: 00000000ffffffff
> [    0.000000] x19: 000000000003fd40 x18: 0000000000000008
> [    0.000000] x17: 0000000400000000 x16: 0000000000000008
> [    0.000000] x15: 0000000000000018 x14: 00000003ffaa0000
> [    0.000000] x13: fffffe0000d6ccc0 x12: 0000000000000080
> [    0.000000] x11: 0000000600000008 x10: 00000003fffd8800
> [    0.000000] x9 : 0000000000000000 x8 : fffffe03febde800
> [    0.000000] x7 : 0000000004fb0000 x6 : fffffe0000d6c0c0
> [    0.000000] x5 : 0000000000001d40 x4 : 0000000000000007
> [    0.000000] x3 : fffffdff60000000 x2 : 0000000000ff0000
> [    0.000000] x1 : 0000000000000001 x0 : 0000000000000001
> [    0.000000]
> [    0.000000] Process swapper (pid: 0, stack limit = 0xfffffe0000af0020)
> [    0.000000] Stack: (0xfffffe0000af3d50 to 0xfffffe0000af4000)
> [    0.000000] 3d40:                                   fffffe0000af3da0 fffffe0000a73f50
> [    0.000000] 3d60: fffffe0000bf8080 000000000002ff40 fffffe0000bf8688 fffffe0000bf7000
> .
> .
> .
> [    0.000000] [<fffffe0000a73c94>] memmap_init_zone+0xd4/0x11c
> [    0.000000] [<fffffe0000a73f50>] free_area_init_node+0x274/0x2bc
> [    0.000000] [<fffffe0000a34ec0>] bootmem_init+0x158/0x198
> [    0.000000] [<fffffe0000a352d0>] paging_init+0xec/0x1a4
> [    0.000000] [<fffffe0000a32ed0>] setup_arch+0x110/0x5a0
> [    0.000000] [<fffffe0000a30680>] start_kernel+0xa8/0x3dc
> [    0.000000] [<fffffe00000811b4>] 0xfffffe00000811b4
> [    0.000000] Code: cb424262 f2dfbfe3 d37ae442 f2ffffe3 (f8636840)
> [    0.000000] ---[ end trace cb88537fdc8fa200 ]---
> [    0.000000] Kernel panic - not syncing: Fatal exception
> [    0.000000] ---[ end Kernel panic - not syncing: Fatal exception

See http://article.gmane.org/gmane.linux.ports.arm.kernel/484866 for a proposed fix.

> Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> ---
>   arch/arm64/include/asm/pgtable.h | 7 +++----
>   arch/arm64/mm/init.c             | 4 ++--
>   2 files changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index f506086..bf464de 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -34,13 +34,13 @@
>   /*
>    * VMALLOC and SPARSEMEM_VMEMMAP ranges.
>    *
> - * VMEMAP_SIZE: allows the whole linear region to be covered by a struct page array
> + * VMEMAP_SIZE: allows the whole VA space to be covered by a struct page array
>    *	(rounded up to PUD_SIZE).
>    * VMALLOC_START: beginning of the kernel VA space
>    * VMALLOC_END: extends to the available space below vmmemmap, PCI I/O space,
>    *	fixed mappings and modules
>    */
> -#define VMEMMAP_SIZE		ALIGN((1UL << (VA_BITS - PAGE_SHIFT - 1)) * sizeof(struct page), PUD_SIZE)
> +#define VMEMMAP_SIZE		ALIGN((1UL << (VA_BITS - PAGE_SHIFT)) * sizeof(struct page), PUD_SIZE)
>
>   #ifndef CONFIG_KASAN
>   #define VMALLOC_START		(VA_START)
> @@ -51,8 +51,7 @@
>
>   #define VMALLOC_END		(PAGE_OFFSET - PUD_SIZE - VMEMMAP_SIZE - SZ_64K)
>
> -#define VMEMMAP_START		(VMALLOC_END + SZ_64K)
> -#define vmemmap			((struct page *)VMEMMAP_START - (memstart_addr >> PAGE_SHIFT))
> +#define vmemmap			((struct page *)(VMALLOC_END + SZ_64K))
>
>   #define FIRST_USER_ADDRESS	0UL
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 7802f21..f3b061e 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -319,8 +319,8 @@ void __init mem_init(void)
>   #endif
>   		  MLG(VMALLOC_START, VMALLOC_END),
>   #ifdef CONFIG_SPARSEMEM_VMEMMAP
> -		  MLG(VMEMMAP_START,
> -		      VMEMMAP_START + VMEMMAP_SIZE),
> +		  MLG((unsigned long)vmemmap,
> +		      (unsigned long)vmemmap + VMEMMAP_SIZE),
>   		  MLM((unsigned long)virt_to_page(PAGE_OFFSET),
>   		      (unsigned long)virt_to_page(high_memory)),
>   #endif