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From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Tue, 16 May 2017 16:03:19 +0100
Message-ID: <CAKv+Gu8xPKhSq=s2PvNQaJLBy7jEhjnADyjsSkOPc4E36VxX1w@mail.gmail.com>
Subject: Re: [PATCH v4] arm64: fix the overlap between the kernel image and
 vmalloc address
Content-Type: text/plain; charset="UTF-8"
Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: zhongjiang <zhongjiang@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>, Mark Rutland <mark.rutland@arm.com>, "linux-mm@kvack.org" <linux-mm@kvack.org>, Tanxiaojun <tanxiaojun@huawei.com>, Laura Abbott <labbott@redhat.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>

On 16 May 2017 at 15:15, zhongjiang <zhongjiang@huawei.com> wrote:
> Recently, xiaojun report the following issue.
>
> [ 4544.984139] Unable to handle kernel paging request at virtual address ffff804392800000
> [ 4544.991995] pgd = ffff80096745f000
> [ 4544.995369] [ffff804392800000] *pgd=0000000000000000
> [ 4545.000297] Internal error: Oops: 96000005 [#1] PREEMPT SMP
> [ 4545.005815] Modules linked in:
> [ 4545.008843] CPU: 1 PID: 8976 Comm: cat Not tainted 4.11.0-rc6 #1
> [ 4545.014790] Hardware name: ARM Juno development board (r1) (DT)
> [ 4545.020653] task: ffff8009753fdb00 task.stack: ffff80097533c000
> [ 4545.026520] PC is at __memcpy+0x100/0x180
> [ 4545.030491] LR is at vread+0x144/0x280
> [ 4545.034202] pc : [<ffff0000083a1000>] lr : [<ffff0000081c126c>] pstate: 20000145
> [ 4545.041530] sp : ffff80097533fcb0
> [ 4545.044811] x29: ffff80097533fcb0 x28: ffff800962d24000
> [ 4545.050074] x27: 0000000000001000 x26: ffff8009753fdb00
> [ 4545.055337] x25: ffff000008200000 x24: ffff800977801380
> [ 4545.060600] x23: ffff8009753fdb00 x22: ffff800962d24000
> [ 4545.065863] x21: 0000000000001000 x20: ffff000008200000
> [ 4545.071125] x19: 0000000000001000 x18: 0000ffffefa323c0
> [ 4545.076387] x17: 0000ffffa9c87440 x16: ffff0000081fdfd0
> [ 4545.081649] x15: 0000ffffa9d01588 x14: 72a77346b2407be7
> [ 4545.086911] x13: 5299400690000000 x12: b0000001f9001a79
> [ 4545.092173] x11: 97fc098d91042260 x10: 0000000000000000
> [ 4545.097435] x9 : 0000000000000000 x8 : 9110626091260021
> [ 4545.102698] x7 : 0000000000001000 x6 : ffff800962d24000
> [ 4545.107960] x5 : ffff8009778013b0 x4 : 0000000000000000
> [ 4545.113222] x3 : 0400000000000001 x2 : 0000000000000f80
> [ 4545.118484] x1 : ffff804392800000 x0 : ffff800962d24000
> [ 4545.123745]
> [ 4545.125220] Process cat (pid: 8976, stack limit = 0xffff80097533c000)
> [ 4545.131598] Stack: (0xffff80097533fcb0 to 0xffff800975340000)
> [ 4545.137289] fca0:                                   ffff80097533fd30 ffff000008270f64
> [ 4545.145049] fcc0: 000000000000e000 000000003956f000 ffff000008f950d0 ffff80097533feb8
> [ 4545.152809] fce0: 0000000000002000 ffff8009753fdb00 ffff800962d24000 ffff000008e8d3d8
> [ 4545.160568] fd00: 0000000000001000 ffff000008200000 0000000000001000 ffff800962d24000
> [ 4545.168327] fd20: 0000000000001000 ffff000008e884a0 ffff80097533fdb0 ffff00000826340c
> [ 4545.176086] fd40: ffff800976bf2800 fffffffffffffffb 000000003956d000 ffff80097533feb8
> [ 4545.183846] fd60: 0000000060000000 0000000000000015 0000000000000124 000000000000003f
> [ 4545.191605] fd80: ffff000008962000 ffff8009753fdb00 ffff8009753fdb00 ffff8009753fdb00
> [ 4545.199364] fda0: 0000000300000124 0000000000002000 ffff80097533fdd0 ffff0000081fb83c
> [ 4545.207123] fdc0: 0000000000010000 ffff80097514f900 ffff80097533fe50 ffff0000081fcb28
> [ 4545.214883] fde0: 0000000000010000 ffff80097514f900 0000000000000000 0000000000000000
> [ 4545.222642] fe00: ffff80097533fe30 ffff0000081fca1c ffff80097514f900 0000000000000000
> [ 4545.230401] fe20: 000000003956d000 ffff80097533feb8 ffff80097533fe50 ffff0000081fcb04
> [ 4545.238160] fe40: 0000000000010000 ffff80097514f900 ffff80097533fe80 ffff0000081fe014
> [ 4545.245919] fe60: ffff80097514f900 ffff80097514f900 000000003956d000 0000000000010000
> [ 4545.253678] fe80: 0000000000000000 ffff000008082f30 0000000000000000 0000800977146000
> [ 4545.261438] fea0: ffffffffffffffff 0000ffffa9c8745c 0000000000000124 0000000008202000
> [ 4545.269197] fec0: 0000000000000003 000000003956d000 0000000000010000 0000000000000000
> [ 4545.276956] fee0: 0000000000011011 0000000000000001 0000000000000011 0000000000000002
> [ 4545.284715] ff00: 000000000000003f 1f3c201f7372686b 00000000ffffffff 0000000000000030
> [ 4545.292474] ff20: 0000000000000038 0000000000000000 0000ffffa9bcca94 0000ffffa9d01588
> [ 4545.300233] ff40: 0000000000000000 0000ffffa9c87440 0000ffffefa323c0 0000000000010000
> [ 4545.307993] ff60: 000000000041a310 000000003956d000 0000000000000003 000000007fffe000
> [ 4545.315751] ff80: 00000000004088d0 0000000000010000 0000000000000000 0000000000000000
> [ 4545.323511] ffa0: 0000000000010000 0000ffffefa32690 0000000000404dcc 0000ffffefa32690
> [ 4545.331270] ffc0: 0000ffffa9c8745c 0000000060000000 0000000000000003 000000000000003f
> [ 4545.339029] ffe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> [ 4545.346786] Call trace:
> [ 4545.349207] Exception stack(0xffff80097533fae0 to 0xffff80097533fc10)
> [ 4545.355586] fae0: 0000000000001000 0001000000000000 ffff80097533fcb0 ffff0000083a1000
> [ 4545.363345] fb00: 000000003957c000 ffff80097533fc00 0000000020000145 0000000000000025
> [ 4545.371105] fb20: ffff800962d24000 ffff000008e8d3d8 0000000000001000 ffff8009753fdb00
> [ 4545.378864] fb40: 0000000000000000 0000000000000002 ffff80097533fd30 ffff000008082604
> [ 4545.386623] fb60: 0000000000001000 0001000000000000 ffff80097533fd30 ffff0000083a0a90
> [ 4545.394382] fb80: ffff800962d24000 ffff804392800000 0000000000000f80 0400000000000001
> [ 4545.402140] fba0: 0000000000000000 ffff8009778013b0 ffff800962d24000 0000000000001000
> [ 4545.409899] fbc0: 9110626091260021 0000000000000000 0000000000000000 97fc098d91042260
> [ 4545.417658] fbe0: b0000001f9001a79 5299400690000000 72a77346b2407be7 0000ffffa9d01588
> [ 4545.425416] fc00: ffff0000081fdfd0 0000ffffa9c87440
> [ 4545.430248] [<ffff0000083a1000>] __memcpy+0x100/0x180
> [ 4545.435253] [<ffff000008270f64>] read_kcore+0x21c/0x3b0
> [ 4545.440429] [<ffff00000826340c>] proc_reg_read+0x64/0x90
> [ 4545.445691] [<ffff0000081fb83c>] __vfs_read+0x1c/0x108
> [ 4545.450779] [<ffff0000081fcb28>] vfs_read+0x80/0x130
> [ 4545.455696] [<ffff0000081fe014>] SyS_read+0x44/0xa0
> [ 4545.460528] [<ffff000008082f30>] el0_svc_naked+0x24/0x28
> [ 4545.465790] Code: d503201f d503201f d503201f d503201f (a8c12027)
> [ 4545.471852] ---[ end trace 4d1897f94759f461 ]---
> [ 4545.476435] note: cat[8976] exited with preempt_count 2
>
> I find the issue is introduced when applying commit f9040773b7bb
> ("arm64: move kernel image to base of vmalloc area"). This patch
> make the kernel image overlap with vmalloc area. It will result in
> vmalloc area have the huge page table. but the vmalloc_to_page is
> not realize the change. and the function is public to any arch.
>
> I fix it by adding the another kernel image condition in vmalloc_to_page
> to make it keep the accordance with previous vmalloc mapping.
>
> Fixes: f9040773b7bb ("arm64: move kernel image to base of vmalloc area")
> Reported-by: tan xiaojun <tanxiaojun@huawei.com>
> Signed-off-by: zhongjiang <zhongjiang@huawei.com>
> Reviewed-by: Laura Abbott <labbott@redhat.com>
> ---
>  arch/arm64/mm/mmu.c     |  2 +-
>  include/linux/vmalloc.h |  1 +
>  mm/vmalloc.c            | 34 +++++++++++++++++++++++++++-------
>  3 files changed, 29 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 0c429ec..2265c39 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -509,7 +509,7 @@ static void __init map_kernel_segment(pgd_t *pgd, void *va_start, void *va_end,
>         vma->addr       = va_start;
>         vma->phys_addr  = pa_start;
>         vma->size       = size;
> -       vma->flags      = VM_MAP;
> +       vma->flags      = VM_KERNEL;
>         vma->caller     = __builtin_return_address(0);
>
>         vm_area_add_early(vma);
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 0328ce0..c9245af 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -17,6 +17,7 @@
>  #define VM_ALLOC               0x00000002      /* vmalloc() */
>  #define VM_MAP                 0x00000004      /* vmap()ed pages */
>  #define VM_USERMAP             0x00000008      /* suitable for remap_vmalloc_range */
> +#define VM_KERNEL              0x00000010      /* kernel pages */

Is it necessary to define this for all architectures? The VM_
namespace explicitly declares a subrange as having architecture scope
iirc

>  #define VM_UNINITIALIZED       0x00000020      /* vm_struct is not fully initialized */
>  #define VM_NO_GUARD            0x00000040      /* don't add guard page */
>  #define VM_KASAN               0x00000080      /* has allocated kasan shadow memory */
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 1dda6d8..b456803 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1967,11 +1967,27 @@ void *vmalloc_32_user(unsigned long size)
>  EXPORT_SYMBOL(vmalloc_32_user);
>
>  /*
> + * VM_KERNEL indicates an address is mapped linearly.The linear mapping may
> + * use larger pages which vmalloc_to_page cannot handle.

Please don't overload 'linear mapping' . We often refer to the direct
kernel mapping mapping of DRAM as 'linear mapping', but in this
context, it is not clear at all what 'linear' means.

> + */
> +static inline struct page *aligned_get_page(char *addr, struct vm_struct *vm)

This function needs a better name

> +{
> +       struct page *p = NULL;
> +
> +       if (vm->flags & VM_KERNEL)
> +               p = virt_to_page(lm_alias(addr));
> +       else
> +               p = vmalloc_to_page(addr);
> +
> +       return p;
> +}
> +
> +/*
>   * small helper routine , copy contents to buf from addr.
>   * If the page is not present, fill zero.
>   */
> -
> -static int aligned_vread(char *buf, char *addr, unsigned long count)
> +static int aligned_vread(char *buf, char *addr, unsigned long count,
> +                                       struct vm_struct *vm)
>  {
>         struct page *p;
>         int copied = 0;
> @@ -1983,7 +1999,7 @@ static int aligned_vread(char *buf, char *addr, unsigned long count)
>                 length = PAGE_SIZE - offset;
>                 if (length > count)
>                         length = count;
> -               p = vmalloc_to_page(addr);
> +               p = aligned_get_page(addr, vm);
>                 /*
>                  * To do safe access to this _mapped_ area, we need
>                  * lock. But adding lock here means that we need to add
> @@ -2010,7 +2026,8 @@ static int aligned_vread(char *buf, char *addr, unsigned long count)
>         return copied;
>  }
>
> -static int aligned_vwrite(char *buf, char *addr, unsigned long count)
> +static int aligned_vwrite(char *buf, char *addr, unsigned long count,
> +                                       struct vm_struct *vm)
>  {
>         struct page *p;
>         int copied = 0;
> @@ -2022,7 +2039,7 @@ static int aligned_vwrite(char *buf, char *addr, unsigned long count)
>                 length = PAGE_SIZE - offset;
>                 if (length > count)
>                         length = count;
> -               p = vmalloc_to_page(addr);
> +               p = aligned_get_page(addr, vm);
>                 /*
>                  * To do safe access to this _mapped_ area, we need
>                  * lock. But adding lock here means that we need to add
> @@ -2109,7 +2126,7 @@ long vread(char *buf, char *addr, unsigned long count)
>                 if (n > count)
>                         n = count;
>                 if (!(vm->flags & VM_IOREMAP))
> -                       aligned_vread(buf, addr, n);
> +                       aligned_vread(buf, addr, n, vm);
>                 else /* IOREMAP area is treated as memory hole */
>                         memset(buf, 0, n);
>                 buf += n;
> @@ -2190,7 +2207,7 @@ long vwrite(char *buf, char *addr, unsigned long count)
>                 if (n > count)
>                         n = count;
>                 if (!(vm->flags & VM_IOREMAP)) {
> -                       aligned_vwrite(buf, addr, n);
> +                       aligned_vwrite(buf, addr, n, vm);
>                         copied++;
>                 }
>                 buf += n;
> @@ -2710,6 +2727,9 @@ static int s_show(struct seq_file *m, void *p)
>         if (v->flags & VM_USERMAP)
>                 seq_puts(m, " user");
>
> +       if (v->flags & VM_KERNEL)
> +               seq_puts(m, " kernel");
> +
>         if (is_vmalloc_addr(v->pages))
>                 seq_puts(m, " vpages");
>
> --
> 1.7.12.4
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

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From mboxrd@z Thu Jan  1 00:00:00 1970
From: ard.biesheuvel@linaro.org (Ard Biesheuvel)
Date: Tue, 16 May 2017 16:03:19 +0100
Subject: [PATCH v4] arm64: fix the overlap between the kernel image and
 vmalloc address
In-Reply-To: <1494944127-41737-1-git-send-email-zhongjiang@huawei.com>
References: <1494944127-41737-1-git-send-email-zhongjiang@huawei.com>
Message-ID: <CAKv+Gu8xPKhSq=s2PvNQaJLBy7jEhjnADyjsSkOPc4E36VxX1w@mail.gmail.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 16 May 2017 at 15:15, zhongjiang <zhongjiang@huawei.com> wrote:
> Recently, xiaojun report the following issue.
>
> [ 4544.984139] Unable to handle kernel paging request at virtual address ffff804392800000
> [ 4544.991995] pgd = ffff80096745f000
> [ 4544.995369] [ffff804392800000] *pgd=0000000000000000
> [ 4545.000297] Internal error: Oops: 96000005 [#1] PREEMPT SMP
> [ 4545.005815] Modules linked in:
> [ 4545.008843] CPU: 1 PID: 8976 Comm: cat Not tainted 4.11.0-rc6 #1
> [ 4545.014790] Hardware name: ARM Juno development board (r1) (DT)
> [ 4545.020653] task: ffff8009753fdb00 task.stack: ffff80097533c000
> [ 4545.026520] PC is at __memcpy+0x100/0x180
> [ 4545.030491] LR is at vread+0x144/0x280
> [ 4545.034202] pc : [<ffff0000083a1000>] lr : [<ffff0000081c126c>] pstate: 20000145
> [ 4545.041530] sp : ffff80097533fcb0
> [ 4545.044811] x29: ffff80097533fcb0 x28: ffff800962d24000
> [ 4545.050074] x27: 0000000000001000 x26: ffff8009753fdb00
> [ 4545.055337] x25: ffff000008200000 x24: ffff800977801380
> [ 4545.060600] x23: ffff8009753fdb00 x22: ffff800962d24000
> [ 4545.065863] x21: 0000000000001000 x20: ffff000008200000
> [ 4545.071125] x19: 0000000000001000 x18: 0000ffffefa323c0
> [ 4545.076387] x17: 0000ffffa9c87440 x16: ffff0000081fdfd0
> [ 4545.081649] x15: 0000ffffa9d01588 x14: 72a77346b2407be7
> [ 4545.086911] x13: 5299400690000000 x12: b0000001f9001a79
> [ 4545.092173] x11: 97fc098d91042260 x10: 0000000000000000
> [ 4545.097435] x9 : 0000000000000000 x8 : 9110626091260021
> [ 4545.102698] x7 : 0000000000001000 x6 : ffff800962d24000
> [ 4545.107960] x5 : ffff8009778013b0 x4 : 0000000000000000
> [ 4545.113222] x3 : 0400000000000001 x2 : 0000000000000f80
> [ 4545.118484] x1 : ffff804392800000 x0 : ffff800962d24000
> [ 4545.123745]
> [ 4545.125220] Process cat (pid: 8976, stack limit = 0xffff80097533c000)
> [ 4545.131598] Stack: (0xffff80097533fcb0 to 0xffff800975340000)
> [ 4545.137289] fca0:                                   ffff80097533fd30 ffff000008270f64
> [ 4545.145049] fcc0: 000000000000e000 000000003956f000 ffff000008f950d0 ffff80097533feb8
> [ 4545.152809] fce0: 0000000000002000 ffff8009753fdb00 ffff800962d24000 ffff000008e8d3d8
> [ 4545.160568] fd00: 0000000000001000 ffff000008200000 0000000000001000 ffff800962d24000
> [ 4545.168327] fd20: 0000000000001000 ffff000008e884a0 ffff80097533fdb0 ffff00000826340c
> [ 4545.176086] fd40: ffff800976bf2800 fffffffffffffffb 000000003956d000 ffff80097533feb8
> [ 4545.183846] fd60: 0000000060000000 0000000000000015 0000000000000124 000000000000003f
> [ 4545.191605] fd80: ffff000008962000 ffff8009753fdb00 ffff8009753fdb00 ffff8009753fdb00
> [ 4545.199364] fda0: 0000000300000124 0000000000002000 ffff80097533fdd0 ffff0000081fb83c
> [ 4545.207123] fdc0: 0000000000010000 ffff80097514f900 ffff80097533fe50 ffff0000081fcb28
> [ 4545.214883] fde0: 0000000000010000 ffff80097514f900 0000000000000000 0000000000000000
> [ 4545.222642] fe00: ffff80097533fe30 ffff0000081fca1c ffff80097514f900 0000000000000000
> [ 4545.230401] fe20: 000000003956d000 ffff80097533feb8 ffff80097533fe50 ffff0000081fcb04
> [ 4545.238160] fe40: 0000000000010000 ffff80097514f900 ffff80097533fe80 ffff0000081fe014
> [ 4545.245919] fe60: ffff80097514f900 ffff80097514f900 000000003956d000 0000000000010000
> [ 4545.253678] fe80: 0000000000000000 ffff000008082f30 0000000000000000 0000800977146000
> [ 4545.261438] fea0: ffffffffffffffff 0000ffffa9c8745c 0000000000000124 0000000008202000
> [ 4545.269197] fec0: 0000000000000003 000000003956d000 0000000000010000 0000000000000000
> [ 4545.276956] fee0: 0000000000011011 0000000000000001 0000000000000011 0000000000000002
> [ 4545.284715] ff00: 000000000000003f 1f3c201f7372686b 00000000ffffffff 0000000000000030
> [ 4545.292474] ff20: 0000000000000038 0000000000000000 0000ffffa9bcca94 0000ffffa9d01588
> [ 4545.300233] ff40: 0000000000000000 0000ffffa9c87440 0000ffffefa323c0 0000000000010000
> [ 4545.307993] ff60: 000000000041a310 000000003956d000 0000000000000003 000000007fffe000
> [ 4545.315751] ff80: 00000000004088d0 0000000000010000 0000000000000000 0000000000000000
> [ 4545.323511] ffa0: 0000000000010000 0000ffffefa32690 0000000000404dcc 0000ffffefa32690
> [ 4545.331270] ffc0: 0000ffffa9c8745c 0000000060000000 0000000000000003 000000000000003f
> [ 4545.339029] ffe0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> [ 4545.346786] Call trace:
> [ 4545.349207] Exception stack(0xffff80097533fae0 to 0xffff80097533fc10)
> [ 4545.355586] fae0: 0000000000001000 0001000000000000 ffff80097533fcb0 ffff0000083a1000
> [ 4545.363345] fb00: 000000003957c000 ffff80097533fc00 0000000020000145 0000000000000025
> [ 4545.371105] fb20: ffff800962d24000 ffff000008e8d3d8 0000000000001000 ffff8009753fdb00
> [ 4545.378864] fb40: 0000000000000000 0000000000000002 ffff80097533fd30 ffff000008082604
> [ 4545.386623] fb60: 0000000000001000 0001000000000000 ffff80097533fd30 ffff0000083a0a90
> [ 4545.394382] fb80: ffff800962d24000 ffff804392800000 0000000000000f80 0400000000000001
> [ 4545.402140] fba0: 0000000000000000 ffff8009778013b0 ffff800962d24000 0000000000001000
> [ 4545.409899] fbc0: 9110626091260021 0000000000000000 0000000000000000 97fc098d91042260
> [ 4545.417658] fbe0: b0000001f9001a79 5299400690000000 72a77346b2407be7 0000ffffa9d01588
> [ 4545.425416] fc00: ffff0000081fdfd0 0000ffffa9c87440
> [ 4545.430248] [<ffff0000083a1000>] __memcpy+0x100/0x180
> [ 4545.435253] [<ffff000008270f64>] read_kcore+0x21c/0x3b0
> [ 4545.440429] [<ffff00000826340c>] proc_reg_read+0x64/0x90
> [ 4545.445691] [<ffff0000081fb83c>] __vfs_read+0x1c/0x108
> [ 4545.450779] [<ffff0000081fcb28>] vfs_read+0x80/0x130
> [ 4545.455696] [<ffff0000081fe014>] SyS_read+0x44/0xa0
> [ 4545.460528] [<ffff000008082f30>] el0_svc_naked+0x24/0x28
> [ 4545.465790] Code: d503201f d503201f d503201f d503201f (a8c12027)
> [ 4545.471852] ---[ end trace 4d1897f94759f461 ]---
> [ 4545.476435] note: cat[8976] exited with preempt_count 2
>
> I find the issue is introduced when applying commit f9040773b7bb
> ("arm64: move kernel image to base of vmalloc area"). This patch
> make the kernel image overlap with vmalloc area. It will result in
> vmalloc area have the huge page table. but the vmalloc_to_page is
> not realize the change. and the function is public to any arch.
>
> I fix it by adding the another kernel image condition in vmalloc_to_page
> to make it keep the accordance with previous vmalloc mapping.
>
> Fixes: f9040773b7bb ("arm64: move kernel image to base of vmalloc area")
> Reported-by: tan xiaojun <tanxiaojun@huawei.com>
> Signed-off-by: zhongjiang <zhongjiang@huawei.com>
> Reviewed-by: Laura Abbott <labbott@redhat.com>
> ---
>  arch/arm64/mm/mmu.c     |  2 +-
>  include/linux/vmalloc.h |  1 +
>  mm/vmalloc.c            | 34 +++++++++++++++++++++++++++-------
>  3 files changed, 29 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 0c429ec..2265c39 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -509,7 +509,7 @@ static void __init map_kernel_segment(pgd_t *pgd, void *va_start, void *va_end,
>         vma->addr       = va_start;
>         vma->phys_addr  = pa_start;
>         vma->size       = size;
> -       vma->flags      = VM_MAP;
> +       vma->flags      = VM_KERNEL;
>         vma->caller     = __builtin_return_address(0);
>
>         vm_area_add_early(vma);
> diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
> index 0328ce0..c9245af 100644
> --- a/include/linux/vmalloc.h
> +++ b/include/linux/vmalloc.h
> @@ -17,6 +17,7 @@
>  #define VM_ALLOC               0x00000002      /* vmalloc() */
>  #define VM_MAP                 0x00000004      /* vmap()ed pages */
>  #define VM_USERMAP             0x00000008      /* suitable for remap_vmalloc_range */
> +#define VM_KERNEL              0x00000010      /* kernel pages */

Is it necessary to define this for all architectures? The VM_
namespace explicitly declares a subrange as having architecture scope
iirc

>  #define VM_UNINITIALIZED       0x00000020      /* vm_struct is not fully initialized */
>  #define VM_NO_GUARD            0x00000040      /* don't add guard page */
>  #define VM_KASAN               0x00000080      /* has allocated kasan shadow memory */
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 1dda6d8..b456803 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1967,11 +1967,27 @@ void *vmalloc_32_user(unsigned long size)
>  EXPORT_SYMBOL(vmalloc_32_user);
>
>  /*
> + * VM_KERNEL indicates an address is mapped linearly.The linear mapping may
> + * use larger pages which vmalloc_to_page cannot handle.

Please don't overload 'linear mapping' . We often refer to the direct
kernel mapping mapping of DRAM as 'linear mapping', but in this
context, it is not clear at all what 'linear' means.

> + */
> +static inline struct page *aligned_get_page(char *addr, struct vm_struct *vm)

This function needs a better name

> +{
> +       struct page *p = NULL;
> +
> +       if (vm->flags & VM_KERNEL)
> +               p = virt_to_page(lm_alias(addr));
> +       else
> +               p = vmalloc_to_page(addr);
> +
> +       return p;
> +}
> +
> +/*
>   * small helper routine , copy contents to buf from addr.
>   * If the page is not present, fill zero.
>   */
> -
> -static int aligned_vread(char *buf, char *addr, unsigned long count)
> +static int aligned_vread(char *buf, char *addr, unsigned long count,
> +                                       struct vm_struct *vm)
>  {
>         struct page *p;
>         int copied = 0;
> @@ -1983,7 +1999,7 @@ static int aligned_vread(char *buf, char *addr, unsigned long count)
>                 length = PAGE_SIZE - offset;
>                 if (length > count)
>                         length = count;
> -               p = vmalloc_to_page(addr);
> +               p = aligned_get_page(addr, vm);
>                 /*
>                  * To do safe access to this _mapped_ area, we need
>                  * lock. But adding lock here means that we need to add
> @@ -2010,7 +2026,8 @@ static int aligned_vread(char *buf, char *addr, unsigned long count)
>         return copied;
>  }
>
> -static int aligned_vwrite(char *buf, char *addr, unsigned long count)
> +static int aligned_vwrite(char *buf, char *addr, unsigned long count,
> +                                       struct vm_struct *vm)
>  {
>         struct page *p;
>         int copied = 0;
> @@ -2022,7 +2039,7 @@ static int aligned_vwrite(char *buf, char *addr, unsigned long count)
>                 length = PAGE_SIZE - offset;
>                 if (length > count)
>                         length = count;
> -               p = vmalloc_to_page(addr);
> +               p = aligned_get_page(addr, vm);
>                 /*
>                  * To do safe access to this _mapped_ area, we need
>                  * lock. But adding lock here means that we need to add
> @@ -2109,7 +2126,7 @@ long vread(char *buf, char *addr, unsigned long count)
>                 if (n > count)
>                         n = count;
>                 if (!(vm->flags & VM_IOREMAP))
> -                       aligned_vread(buf, addr, n);
> +                       aligned_vread(buf, addr, n, vm);
>                 else /* IOREMAP area is treated as memory hole */
>                         memset(buf, 0, n);
>                 buf += n;
> @@ -2190,7 +2207,7 @@ long vwrite(char *buf, char *addr, unsigned long count)
>                 if (n > count)
>                         n = count;
>                 if (!(vm->flags & VM_IOREMAP)) {
> -                       aligned_vwrite(buf, addr, n);
> +                       aligned_vwrite(buf, addr, n, vm);
>                         copied++;
>                 }
>                 buf += n;
> @@ -2710,6 +2727,9 @@ static int s_show(struct seq_file *m, void *p)
>         if (v->flags & VM_USERMAP)
>                 seq_puts(m, " user");
>
> +       if (v->flags & VM_KERNEL)
> +               seq_puts(m, " kernel");
> +
>         if (is_vmalloc_addr(v->pages))
>                 seq_puts(m, " vpages");
>
> --
> 1.7.12.4
>
>
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