Re: [PATCH] Fix "vtop" command to display the swapinfo for arm64 kernel 5.19.0+

[Guanyou Chen <chenguanyou9338@xxxxxxxxx>]

Thank you for review, Lianbo.

Kazu, Can you help improve the patch log.

Thanks

Guanyou

lijiang <lijiang@xxxxxxxxxx> 于2023年9月27日周三 19:35写道：

Thank you for the update, Chen.

On Tue, Sep 26, 2023 at 8:44 PM Guanyou Chen <chenguanyou9338@xxxxxxxxx> wrote:

arm64/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE

We can add the kernel commit to patch log as I mentioned here:

https://listman.redhat.com/archives/crash-utility/2023-September/011010.html

570ef363509b ("arm64/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE") 

Otherwise, for the patch: Ack.

BTW: maybe Kazu can help improve the patch log when merging(if the patch is also fine to him).

Thanks

Lianbo

Let's use one of the type bits: core-mm only supports 5, so there is no
need to consume 6.

Note that we might be able to reuse bit 1, but reusing bit 1 turned out
problematic in the past for PROT_NONE handling; so let's play safe and use
another bit.

Link: https://lkml.kernel.org/r/20220329164329.208407-5-david@xxxxxxxxxx

Before:
crash> vtop 70504000
VIRTUAL     PHYSICAL
70504000    (not mapped)

PAGE DIRECTORY: ffffff80f265c000
   PGD: ffffff80f265c008 => 800000141537003
   PMD: ffffff8101537c10 => 800000141538003
   PTE: ffffff8101538820 => 12bc3e04

  PTE     vtop: cannot determine swap location

After:
crash> vtop 70504000
VIRTUAL     PHYSICAL
70504000    (not mapped)

PAGE DIRECTORY: ffffff80f265c000
   PGD: ffffff80f265c008 => 800000141537003
   PMD: ffffff8101537c10 => 800000141538003
   PTE: ffffff8101538820 => 12bc3e04

  PTE                     SWAP                  OFFSET
12bc3e04  /first_stage_ramdisk/dev/block/zram0  1227838

      VMA           START       END     FLAGS FILE
ffffff80dfe7b578   70504000   707bd000 100073

SWAP: /first_stage_ramdisk/dev/block/zram0  OFFSET: 1227838

Signed-off-by: chenguanyou <chenguanyou@xxxxxxxxxx>

---
 arm64.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/arm64.c b/arm64.c
index 39d5f04..ea1b51b 100644
--- a/arm64.c
+++ b/arm64.c
@@ -468,8 +468,16 @@ arm64_init(int when)
            }
        }

-
-       if (THIS_KERNEL_VERSION >= LINUX(4,0,0)) {
+       if (THIS_KERNEL_VERSION >= LINUX(5,19,0)) {
+           ms->__SWP_TYPE_BITS = 5;
+           ms->__SWP_TYPE_SHIFT = 3;
+           ms->__SWP_TYPE_MASK = ((1UL << ms->__SWP_TYPE_BITS) - 1);
+           ms->__SWP_OFFSET_SHIFT = (ms->__SWP_TYPE_BITS + ms->__SWP_TYPE_SHIFT);
+           ms->__SWP_OFFSET_BITS = 50;
+           ms->__SWP_OFFSET_MASK = ((1UL << ms->__SWP_OFFSET_BITS) - 1);
+           ms->PTE_PROT_NONE = (1UL << 58);
+           ms->PTE_FILE = 0;  /* unused */
+       } else if (THIS_KERNEL_VERSION >= LINUX(4,0,0)) {
            ms->__SWP_TYPE_BITS = 6;
            ms->__SWP_TYPE_SHIFT = 2;
            ms->__SWP_TYPE_MASK = ((1UL << ms->__SWP_TYPE_BITS) - 1);
--
2.39.0

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