[v4,0/3] Append new variables to vmcoreinfo (TCR_EL1.T1SZ for arm64 and MAX_PHYSMEM_BITS for all archs)

Message

Bhupesh Sharma Nov. 11, 2019, 8:01 a.m. UTC

Changes since v3:
----------------
- v3 can be seen here:
  http://lists.infradead.org/pipermail/kexec/2019-March/022590.html
- Addressed comments from James and exported TCR_EL1.T1SZ in vmcoreinfo
  instead of PTRS_PER_PGD.
- Added a new patch (via [PATCH 3/3]), which fixes a simple typo in
  'Documentation/arm64/memory.rst'

Changes since v2:
----------------
- v2 can be seen here:
  http://lists.infradead.org/pipermail/kexec/2019-March/022531.html
- Protected 'MAX_PHYSMEM_BITS' vmcoreinfo variable under CONFIG_SPARSEMEM
  ifdef sections, as suggested by Kazu.
- Updated vmcoreinfo documentation to add description about
  'MAX_PHYSMEM_BITS' variable (via [PATCH 3/3]).

Changes since v1:
----------------
- v1 was sent out as a single patch which can be seen here:
  http://lists.infradead.org/pipermail/kexec/2019-February/022411.html

- v2 breaks the single patch into two independent patches:
  [PATCH 1/2] appends 'PTRS_PER_PGD' to vmcoreinfo for arm64 arch, whereas
  [PATCH 2/2] appends 'MAX_PHYSMEM_BITS' to vmcoreinfo in core kernel code (all archs)

This patchset primarily fixes the regression reported in user-space
utilities like 'makedumpfile' and 'crash-utility' on arm64 architecture
with the availability of 52-bit address space feature in underlying
kernel. These regressions have been reported both on CPUs which don't
support ARMv8.2 extensions (i.e. LVA, LPA) and are running newer kernels
and also on prototype platforms (like ARMv8 FVP simulator model) which
support ARMv8.2 extensions and are running newer kernels.

The reason for these regressions is that right now user-space tools
have no direct access to these values (since these are not exported
from the kernel) and hence need to rely on a best-guess method of
determining value of 'vabits_actual' and 'MAX_PHYSMEM_BITS' supported
by underlying kernel.

Exporting these values via vmcoreinfo will help user-land in such cases.
In addition, as per suggestion from makedumpfile maintainer (Kazu),
it makes more sense to append 'MAX_PHYSMEM_BITS' to
vmcoreinfo in the core code itself rather than in arm64 arch-specific
code, so that the user-space code for other archs can also benefit from
this addition to the vmcoreinfo and use it as a standard way of
determining 'SECTIONS_SHIFT' value in user-land.

Cc: Boris Petkov <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Jonathan Corbet <[e-mail]>
Cc: James Morse <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Steve Capper <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: Ard Biesheuvel <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Dave Anderson <[e-mail]>
Cc: Kazuhito Hagio <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]

Bhupesh Sharma (3):
  crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
  arm64/crash_core: Export TCR_EL1.T1SZ in vmcoreinfo
  Documentation/arm64: Fix a simple typo in memory.rst

 Documentation/arm64/memory.rst         | 2 +-
 arch/arm64/include/asm/pgtable-hwdef.h | 1 +
 arch/arm64/kernel/crash_core.c         | 9 +++++++++
 kernel/crash_core.c                    | 1 +
 4 files changed, 12 insertions(+), 1 deletion(-)

Comments

AKASHI Takahiro Nov. 13, 2019, 6:39 a.m. UTC | #1

Hi Bhupesh,

Do you have a corresponding patch for userspace tools,
including crash util and/or makedumpfile?
Otherwise, we can't verify that a generated core file is
correctly handled.

Thanks,
-Takahiro Akashi

On Mon, Nov 11, 2019 at 01:31:19PM +0530, Bhupesh Sharma wrote:
> Changes since v3:
> ----------------
> - v3 can be seen here:
>   http://lists.infradead.org/pipermail/kexec/2019-March/022590.html
> - Addressed comments from James and exported TCR_EL1.T1SZ in vmcoreinfo
>   instead of PTRS_PER_PGD.
> - Added a new patch (via [PATCH 3/3]), which fixes a simple typo in
>   'Documentation/arm64/memory.rst'
> 
> Changes since v2:
> ----------------
> - v2 can be seen here:
>   http://lists.infradead.org/pipermail/kexec/2019-March/022531.html
> - Protected 'MAX_PHYSMEM_BITS' vmcoreinfo variable under CONFIG_SPARSEMEM
>   ifdef sections, as suggested by Kazu.
> - Updated vmcoreinfo documentation to add description about
>   'MAX_PHYSMEM_BITS' variable (via [PATCH 3/3]).
> 
> Changes since v1:
> ----------------
> - v1 was sent out as a single patch which can be seen here:
>   http://lists.infradead.org/pipermail/kexec/2019-February/022411.html
> 
> - v2 breaks the single patch into two independent patches:
>   [PATCH 1/2] appends 'PTRS_PER_PGD' to vmcoreinfo for arm64 arch, whereas
>   [PATCH 2/2] appends 'MAX_PHYSMEM_BITS' to vmcoreinfo in core kernel code (all archs)
> 
> This patchset primarily fixes the regression reported in user-space
> utilities like 'makedumpfile' and 'crash-utility' on arm64 architecture
> with the availability of 52-bit address space feature in underlying
> kernel. These regressions have been reported both on CPUs which don't
> support ARMv8.2 extensions (i.e. LVA, LPA) and are running newer kernels
> and also on prototype platforms (like ARMv8 FVP simulator model) which
> support ARMv8.2 extensions and are running newer kernels.
> 
> The reason for these regressions is that right now user-space tools
> have no direct access to these values (since these are not exported
> from the kernel) and hence need to rely on a best-guess method of
> determining value of 'vabits_actual' and 'MAX_PHYSMEM_BITS' supported
> by underlying kernel.
> 
> Exporting these values via vmcoreinfo will help user-land in such cases.
> In addition, as per suggestion from makedumpfile maintainer (Kazu),
> it makes more sense to append 'MAX_PHYSMEM_BITS' to
> vmcoreinfo in the core code itself rather than in arm64 arch-specific
> code, so that the user-space code for other archs can also benefit from
> this addition to the vmcoreinfo and use it as a standard way of
> determining 'SECTIONS_SHIFT' value in user-land.
> 
> Cc: Boris Petkov <[e-mail]>
> Cc: Ingo Molnar <[e-mail]>
> Cc: Thomas Gleixner <[e-mail]>
> Cc: Jonathan Corbet <[e-mail]>
> Cc: James Morse <[e-mail]>
> Cc: Mark Rutland <[e-mail]>
> Cc: Will Deacon <[e-mail]>
> Cc: Steve Capper <[e-mail]>
> Cc: Catalin Marinas <[e-mail]>
> Cc: Ard Biesheuvel <[e-mail]>
> Cc: Michael Ellerman <[e-mail]>
> Cc: Paul Mackerras <[e-mail]>
> Cc: Benjamin Herrenschmidt <[e-mail]>
> Cc: Dave Anderson <[e-mail]>
> Cc: Kazuhito Hagio <[e-mail]>
> Cc: [e-mail]
> Cc: [e-mail]
> Cc: [e-mail]
> Cc: [e-mail]
> Cc: [e-mail]
> Cc: [e-mail]
> 
> Bhupesh Sharma (3):
>   crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
>   arm64/crash_core: Export TCR_EL1.T1SZ in vmcoreinfo
>   Documentation/arm64: Fix a simple typo in memory.rst
> 
>  Documentation/arm64/memory.rst         | 2 +-
>  arch/arm64/include/asm/pgtable-hwdef.h | 1 +
>  arch/arm64/kernel/crash_core.c         | 9 +++++++++
>  kernel/crash_core.c                    | 1 +
>  4 files changed, 12 insertions(+), 1 deletion(-)
> 
> -- 
> 2.7.4
>

Bhupesh Sharma Nov. 14, 2019, 7:54 p.m. UTC | #2

Hi Akashi,

On Wed, Nov 13, 2019 at 12:11 PM AKASHI Takahiro
<[e-mail]> wrote:
>
> Hi Bhupesh,
>
> Do you have a corresponding patch for userspace tools,
> including crash util and/or makedumpfile?
> Otherwise, we can't verify that a generated core file is
> correctly handled.

Sure. I am still working on the crash-utility related changes, but you
can find the makedumpfile changes I posted a couple of days ago here
(see [0]) and the github link for the makedumpfile changes can be seen
via [1].

I will post the crash-util changes shortly as well.
Thanks for having a look at the same.

[0]. http://lists.infradead.org/pipermail/kexec/2019-November/023963.html
[1]. https://github.com/bhupesh-sharma/makedumpfile/tree/52-bit-va-support-via-vmcore-upstream-v4

Regards,
Bhupesh

>
> Thanks,
> -Takahiro Akashi
>
> On Mon, Nov 11, 2019 at 01:31:19PM +0530, Bhupesh Sharma wrote:
> > Changes since v3:
> > ----------------
> > - v3 can be seen here:
> >   http://lists.infradead.org/pipermail/kexec/2019-March/022590.html
> > - Addressed comments from James and exported TCR_EL1.T1SZ in vmcoreinfo
> >   instead of PTRS_PER_PGD.
> > - Added a new patch (via [PATCH 3/3]), which fixes a simple typo in
> >   'Documentation/arm64/memory.rst'
> >
> > Changes since v2:
> > ----------------
> > - v2 can be seen here:
> >   http://lists.infradead.org/pipermail/kexec/2019-March/022531.html
> > - Protected 'MAX_PHYSMEM_BITS' vmcoreinfo variable under CONFIG_SPARSEMEM
> >   ifdef sections, as suggested by Kazu.
> > - Updated vmcoreinfo documentation to add description about
> >   'MAX_PHYSMEM_BITS' variable (via [PATCH 3/3]).
> >
> > Changes since v1:
> > ----------------
> > - v1 was sent out as a single patch which can be seen here:
> >   http://lists.infradead.org/pipermail/kexec/2019-February/022411.html
> >
> > - v2 breaks the single patch into two independent patches:
> >   [PATCH 1/2] appends 'PTRS_PER_PGD' to vmcoreinfo for arm64 arch, whereas
> >   [PATCH 2/2] appends 'MAX_PHYSMEM_BITS' to vmcoreinfo in core kernel code (all archs)
> >
> > This patchset primarily fixes the regression reported in user-space
> > utilities like 'makedumpfile' and 'crash-utility' on arm64 architecture
> > with the availability of 52-bit address space feature in underlying
> > kernel. These regressions have been reported both on CPUs which don't
> > support ARMv8.2 extensions (i.e. LVA, LPA) and are running newer kernels
> > and also on prototype platforms (like ARMv8 FVP simulator model) which
> > support ARMv8.2 extensions and are running newer kernels.
> >
> > The reason for these regressions is that right now user-space tools
> > have no direct access to these values (since these are not exported
> > from the kernel) and hence need to rely on a best-guess method of
> > determining value of 'vabits_actual' and 'MAX_PHYSMEM_BITS' supported
> > by underlying kernel.
> >
> > Exporting these values via vmcoreinfo will help user-land in such cases.
> > In addition, as per suggestion from makedumpfile maintainer (Kazu),
> > it makes more sense to append 'MAX_PHYSMEM_BITS' to
> > vmcoreinfo in the core code itself rather than in arm64 arch-specific
> > code, so that the user-space code for other archs can also benefit from
> > this addition to the vmcoreinfo and use it as a standard way of
> > determining 'SECTIONS_SHIFT' value in user-land.
> >
> > Cc: Boris Petkov <[e-mail]>
> > Cc: Ingo Molnar <[e-mail]>
> > Cc: Thomas Gleixner <[e-mail]>
> > Cc: Jonathan Corbet <[e-mail]>
> > Cc: James Morse <[e-mail]>
> > Cc: Mark Rutland <[e-mail]>
> > Cc: Will Deacon <[e-mail]>
> > Cc: Steve Capper <[e-mail]>
> > Cc: Catalin Marinas <[e-mail]>
> > Cc: Ard Biesheuvel <[e-mail]>
> > Cc: Michael Ellerman <[e-mail]>
> > Cc: Paul Mackerras <[e-mail]>
> > Cc: Benjamin Herrenschmidt <[e-mail]>
> > Cc: Dave Anderson <[e-mail]>
> > Cc: Kazuhito Hagio <[e-mail]>
> > Cc: [e-mail]
> > Cc: [e-mail]
> > Cc: [e-mail]
> > Cc: [e-mail]
> > Cc: [e-mail]
> > Cc: [e-mail]
> >
> > Bhupesh Sharma (3):
> >   crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
> >   arm64/crash_core: Export TCR_EL1.T1SZ in vmcoreinfo
> >   Documentation/arm64: Fix a simple typo in memory.rst
> >
> >  Documentation/arm64/memory.rst         | 2 +-
> >  arch/arm64/include/asm/pgtable-hwdef.h | 1 +
> >  arch/arm64/kernel/crash_core.c         | 9 +++++++++
> >  kernel/crash_core.c                    | 1 +
> >  4 files changed, 12 insertions(+), 1 deletion(-)
> >
> > --
> > 2.7.4
> >
>

AKASHI Takahiro Nov. 15, 2019, 2 a.m. UTC | #3

Bhupesh,

On Fri, Nov 15, 2019 at 01:24:17AM +0530, Bhupesh Sharma wrote:
> Hi Akashi,
> 
> On Wed, Nov 13, 2019 at 12:11 PM AKASHI Takahiro
> <[e-mail]> wrote:
> >
> > Hi Bhupesh,
> >
> > Do you have a corresponding patch for userspace tools,
> > including crash util and/or makedumpfile?
> > Otherwise, we can't verify that a generated core file is
> > correctly handled.
> 
> Sure. I am still working on the crash-utility related changes, but you
> can find the makedumpfile changes I posted a couple of days ago here
> (see [0]) and the github link for the makedumpfile changes can be seen
> via [1].
> 
> I will post the crash-util changes shortly as well.
> Thanks for having a look at the same.

Thank you.
I have tested my kdump patch with a hacked version of crash
where VA_BITS_ACTUAL is calculated from tcr_el1_t1sz in vmcoreinfo.

-Takahiro Akashi


> [0]. http://lists.infradead.org/pipermail/kexec/2019-November/023963.html
> [1]. https://github.com/bhupesh-sharma/makedumpfile/tree/52-bit-va-support-via-vmcore-upstream-v4
> 
> Regards,
> Bhupesh
> 
> >
> > Thanks,
> > -Takahiro Akashi
> >
> > On Mon, Nov 11, 2019 at 01:31:19PM +0530, Bhupesh Sharma wrote:
> > > Changes since v3:
> > > ----------------
> > > - v3 can be seen here:
> > >   http://lists.infradead.org/pipermail/kexec/2019-March/022590.html
> > > - Addressed comments from James and exported TCR_EL1.T1SZ in vmcoreinfo
> > >   instead of PTRS_PER_PGD.
> > > - Added a new patch (via [PATCH 3/3]), which fixes a simple typo in
> > >   'Documentation/arm64/memory.rst'
> > >
> > > Changes since v2:
> > > ----------------
> > > - v2 can be seen here:
> > >   http://lists.infradead.org/pipermail/kexec/2019-March/022531.html
> > > - Protected 'MAX_PHYSMEM_BITS' vmcoreinfo variable under CONFIG_SPARSEMEM
> > >   ifdef sections, as suggested by Kazu.
> > > - Updated vmcoreinfo documentation to add description about
> > >   'MAX_PHYSMEM_BITS' variable (via [PATCH 3/3]).
> > >
> > > Changes since v1:
> > > ----------------
> > > - v1 was sent out as a single patch which can be seen here:
> > >   http://lists.infradead.org/pipermail/kexec/2019-February/022411.html
> > >
> > > - v2 breaks the single patch into two independent patches:
> > >   [PATCH 1/2] appends 'PTRS_PER_PGD' to vmcoreinfo for arm64 arch, whereas
> > >   [PATCH 2/2] appends 'MAX_PHYSMEM_BITS' to vmcoreinfo in core kernel code (all archs)
> > >
> > > This patchset primarily fixes the regression reported in user-space
> > > utilities like 'makedumpfile' and 'crash-utility' on arm64 architecture
> > > with the availability of 52-bit address space feature in underlying
> > > kernel. These regressions have been reported both on CPUs which don't
> > > support ARMv8.2 extensions (i.e. LVA, LPA) and are running newer kernels
> > > and also on prototype platforms (like ARMv8 FVP simulator model) which
> > > support ARMv8.2 extensions and are running newer kernels.
> > >
> > > The reason for these regressions is that right now user-space tools
> > > have no direct access to these values (since these are not exported
> > > from the kernel) and hence need to rely on a best-guess method of
> > > determining value of 'vabits_actual' and 'MAX_PHYSMEM_BITS' supported
> > > by underlying kernel.
> > >
> > > Exporting these values via vmcoreinfo will help user-land in such cases.
> > > In addition, as per suggestion from makedumpfile maintainer (Kazu),
> > > it makes more sense to append 'MAX_PHYSMEM_BITS' to
> > > vmcoreinfo in the core code itself rather than in arm64 arch-specific
> > > code, so that the user-space code for other archs can also benefit from
> > > this addition to the vmcoreinfo and use it as a standard way of
> > > determining 'SECTIONS_SHIFT' value in user-land.
> > >
> > > Cc: Boris Petkov <[e-mail]>
> > > Cc: Ingo Molnar <[e-mail]>
> > > Cc: Thomas Gleixner <[e-mail]>
> > > Cc: Jonathan Corbet <[e-mail]>
> > > Cc: James Morse <[e-mail]>
> > > Cc: Mark Rutland <[e-mail]>
> > > Cc: Will Deacon <[e-mail]>
> > > Cc: Steve Capper <[e-mail]>
> > > Cc: Catalin Marinas <[e-mail]>
> > > Cc: Ard Biesheuvel <[e-mail]>
> > > Cc: Michael Ellerman <[e-mail]>
> > > Cc: Paul Mackerras <[e-mail]>
> > > Cc: Benjamin Herrenschmidt <[e-mail]>
> > > Cc: Dave Anderson <[e-mail]>
> > > Cc: Kazuhito Hagio <[e-mail]>
> > > Cc: [e-mail]
> > > Cc: [e-mail]
> > > Cc: [e-mail]
> > > Cc: [e-mail]
> > > Cc: [e-mail]
> > > Cc: [e-mail]
> > >
> > > Bhupesh Sharma (3):
> > >   crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
> > >   arm64/crash_core: Export TCR_EL1.T1SZ in vmcoreinfo
> > >   Documentation/arm64: Fix a simple typo in memory.rst
> > >
> > >  Documentation/arm64/memory.rst         | 2 +-
> > >  arch/arm64/include/asm/pgtable-hwdef.h | 1 +
> > >  arch/arm64/kernel/crash_core.c         | 9 +++++++++
> > >  kernel/crash_core.c                    | 1 +
> > >  4 files changed, 12 insertions(+), 1 deletion(-)
> > >
> > > --
> > > 2.7.4
> > >
> >
>

Bhupesh Sharma Nov. 16, 2019, 7:31 p.m. UTC | #4

Hi Akashi,

On Fri, Nov 15, 2019 at 7:29 AM AKASHI Takahiro
<[e-mail]> wrote:
>
> Bhupesh,
>
> On Fri, Nov 15, 2019 at 01:24:17AM +0530, Bhupesh Sharma wrote:
> > Hi Akashi,
> >
> > On Wed, Nov 13, 2019 at 12:11 PM AKASHI Takahiro
> > <[e-mail]> wrote:
> > >
> > > Hi Bhupesh,
> > >
> > > Do you have a corresponding patch for userspace tools,
> > > including crash util and/or makedumpfile?
> > > Otherwise, we can't verify that a generated core file is
> > > correctly handled.
> >
> > Sure. I am still working on the crash-utility related changes, but you
> > can find the makedumpfile changes I posted a couple of days ago here
> > (see [0]) and the github link for the makedumpfile changes can be seen
> > via [1].
> >
> > I will post the crash-util changes shortly as well.
> > Thanks for having a look at the same.
>
> Thank you.
> I have tested my kdump patch with a hacked version of crash
> where VA_BITS_ACTUAL is calculated from tcr_el1_t1sz in vmcoreinfo.

Thanks a lot for testing the changes. I will push the crash utility
changes for review shortly and also Cc you to the patches.
It would be great to have your Tested-by for this patch-set, if the
user-space works fine for you with these changes.

Regards,
Bhupesh

> -Takahiro Akashi
>
>
> > [0]. http://lists.infradead.org/pipermail/kexec/2019-November/023963.html
> > [1]. https://github.com/bhupesh-sharma/makedumpfile/tree/52-bit-va-support-via-vmcore-upstream-v4
> >
> > Regards,
> > Bhupesh
> >
> > >
> > > Thanks,
> > > -Takahiro Akashi
> > >
> > > On Mon, Nov 11, 2019 at 01:31:19PM +0530, Bhupesh Sharma wrote:
> > > > Changes since v3:
> > > > ----------------
> > > > - v3 can be seen here:
> > > >   http://lists.infradead.org/pipermail/kexec/2019-March/022590.html
> > > > - Addressed comments from James and exported TCR_EL1.T1SZ in vmcoreinfo
> > > >   instead of PTRS_PER_PGD.
> > > > - Added a new patch (via [PATCH 3/3]), which fixes a simple typo in
> > > >   'Documentation/arm64/memory.rst'
> > > >
> > > > Changes since v2:
> > > > ----------------
> > > > - v2 can be seen here:
> > > >   http://lists.infradead.org/pipermail/kexec/2019-March/022531.html
> > > > - Protected 'MAX_PHYSMEM_BITS' vmcoreinfo variable under CONFIG_SPARSEMEM
> > > >   ifdef sections, as suggested by Kazu.
> > > > - Updated vmcoreinfo documentation to add description about
> > > >   'MAX_PHYSMEM_BITS' variable (via [PATCH 3/3]).
> > > >
> > > > Changes since v1:
> > > > ----------------
> > > > - v1 was sent out as a single patch which can be seen here:
> > > >   http://lists.infradead.org/pipermail/kexec/2019-February/022411.html
> > > >
> > > > - v2 breaks the single patch into two independent patches:
> > > >   [PATCH 1/2] appends 'PTRS_PER_PGD' to vmcoreinfo for arm64 arch, whereas
> > > >   [PATCH 2/2] appends 'MAX_PHYSMEM_BITS' to vmcoreinfo in core kernel code (all archs)
> > > >
> > > > This patchset primarily fixes the regression reported in user-space
> > > > utilities like 'makedumpfile' and 'crash-utility' on arm64 architecture
> > > > with the availability of 52-bit address space feature in underlying
> > > > kernel. These regressions have been reported both on CPUs which don't
> > > > support ARMv8.2 extensions (i.e. LVA, LPA) and are running newer kernels
> > > > and also on prototype platforms (like ARMv8 FVP simulator model) which
> > > > support ARMv8.2 extensions and are running newer kernels.
> > > >
> > > > The reason for these regressions is that right now user-space tools
> > > > have no direct access to these values (since these are not exported
> > > > from the kernel) and hence need to rely on a best-guess method of
> > > > determining value of 'vabits_actual' and 'MAX_PHYSMEM_BITS' supported
> > > > by underlying kernel.
> > > >
> > > > Exporting these values via vmcoreinfo will help user-land in such cases.
> > > > In addition, as per suggestion from makedumpfile maintainer (Kazu),
> > > > it makes more sense to append 'MAX_PHYSMEM_BITS' to
> > > > vmcoreinfo in the core code itself rather than in arm64 arch-specific
> > > > code, so that the user-space code for other archs can also benefit from
> > > > this addition to the vmcoreinfo and use it as a standard way of
> > > > determining 'SECTIONS_SHIFT' value in user-land.
> > > >
> > > > Cc: Boris Petkov <[e-mail]>
> > > > Cc: Ingo Molnar <[e-mail]>
> > > > Cc: Thomas Gleixner <[e-mail]>
> > > > Cc: Jonathan Corbet <[e-mail]>
> > > > Cc: James Morse <[e-mail]>
> > > > Cc: Mark Rutland <[e-mail]>
> > > > Cc: Will Deacon <[e-mail]>
> > > > Cc: Steve Capper <[e-mail]>
> > > > Cc: Catalin Marinas <[e-mail]>
> > > > Cc: Ard Biesheuvel <[e-mail]>
> > > > Cc: Michael Ellerman <[e-mail]>
> > > > Cc: Paul Mackerras <[e-mail]>
> > > > Cc: Benjamin Herrenschmidt <[e-mail]>
> > > > Cc: Dave Anderson <[e-mail]>
> > > > Cc: Kazuhito Hagio <[e-mail]>
> > > > Cc: [e-mail]
> > > > Cc: [e-mail]
> > > > Cc: [e-mail]
> > > > Cc: [e-mail]
> > > > Cc: [e-mail]
> > > > Cc: [e-mail]
> > > >
> > > > Bhupesh Sharma (3):
> > > >   crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
> > > >   arm64/crash_core: Export TCR_EL1.T1SZ in vmcoreinfo
> > > >   Documentation/arm64: Fix a simple typo in memory.rst
> > > >
> > > >  Documentation/arm64/memory.rst         | 2 +-
> > > >  arch/arm64/include/asm/pgtable-hwdef.h | 1 +
> > > >  arch/arm64/kernel/crash_core.c         | 9 +++++++++
> > > >  kernel/crash_core.c                    | 1 +
> > > >  4 files changed, 12 insertions(+), 1 deletion(-)
> > > >
> > > > --
> > > > 2.7.4
> > > >
> > >
> >
>

Prabhakar Kushwaha Nov. 19, 2019, 6:32 a.m. UTC | #5

Hi Akashi,

On Fri, Nov 15, 2019 at 7:29 AM AKASHI Takahiro
<[e-mail]> wrote:
>
> Bhupesh,
>
> On Fri, Nov 15, 2019 at 01:24:17AM +0530, Bhupesh Sharma wrote:
> > Hi Akashi,
> >
> > On Wed, Nov 13, 2019 at 12:11 PM AKASHI Takahiro
> > <[e-mail]> wrote:
> > >
> > > Hi Bhupesh,
> > >
> > > Do you have a corresponding patch for userspace tools,
> > > including crash util and/or makedumpfile?
> > > Otherwise, we can't verify that a generated core file is
> > > correctly handled.
> >
> > Sure. I am still working on the crash-utility related changes, but you
> > can find the makedumpfile changes I posted a couple of days ago here
> > (see [0]) and the github link for the makedumpfile changes can be seen
> > via [1].
> >
> > I will post the crash-util changes shortly as well.
> > Thanks for having a look at the same.
>
> Thank you.
> I have tested my kdump patch with a hacked version of crash
> where VA_BITS_ACTUAL is calculated from tcr_el1_t1sz in vmcoreinfo.
>

I also did hack to calculate VA_BITS_ACTUAL is calculated from
tcr_el1_t1sz in vmcoreinfo. Now i am getting error same as mentioned
by you in other thread last month.
https://www.mail-archive.com/[e-mail]/msg07385.html

how this error was overcome?

I am using
 - crashkernel: https://github.com/crash-utility/crash.git  commit:
babd7ae62d4e8fd6f93fd30b88040d9376522aa3
and
 - Linux: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
commit: af42d3466bdc8f39806b26f593604fdc54140bcb

--pk

AKASHI Takahiro Nov. 19, 2019, 7:13 a.m. UTC | #6

Hi Prabhakar,

On Tue, Nov 19, 2019 at 12:02:46PM +0530, Prabhakar Kushwaha wrote:
> Hi Akashi,
> 
> On Fri, Nov 15, 2019 at 7:29 AM AKASHI Takahiro
> <[e-mail]> wrote:
> >
> > Bhupesh,
> >
> > On Fri, Nov 15, 2019 at 01:24:17AM +0530, Bhupesh Sharma wrote:
> > > Hi Akashi,
> > >
> > > On Wed, Nov 13, 2019 at 12:11 PM AKASHI Takahiro
> > > <[e-mail]> wrote:
> > > >
> > > > Hi Bhupesh,
> > > >
> > > > Do you have a corresponding patch for userspace tools,
> > > > including crash util and/or makedumpfile?
> > > > Otherwise, we can't verify that a generated core file is
> > > > correctly handled.
> > >
> > > Sure. I am still working on the crash-utility related changes, but you
> > > can find the makedumpfile changes I posted a couple of days ago here
> > > (see [0]) and the github link for the makedumpfile changes can be seen
> > > via [1].
> > >
> > > I will post the crash-util changes shortly as well.
> > > Thanks for having a look at the same.
> >
> > Thank you.
> > I have tested my kdump patch with a hacked version of crash
> > where VA_BITS_ACTUAL is calculated from tcr_el1_t1sz in vmcoreinfo.
> >
> 
> I also did hack to calculate VA_BITS_ACTUAL is calculated from
> tcr_el1_t1sz in vmcoreinfo. Now i am getting error same as mentioned
> by you in other thread last month.
> https://www.mail-archive.com/[e-mail]/msg07385.html
> 
> how this error was overcome?
> 
> I am using
>  - crashkernel: https://github.com/crash-utility/crash.git  commit:
> babd7ae62d4e8fd6f93fd30b88040d9376522aa3
> and
>  - Linux: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> commit: af42d3466bdc8f39806b26f593604fdc54140bcb

# I am rather reluctant to cross-post non-kernel patch to lkml/lakml,

The only change I made to crash utility was:
===8<===
diff --git a/arm64.c b/arm64.c
index 5ee5f1a29a41..84e40aeb561b 100644
--- a/arm64.c
+++ b/arm64.c
@@ -3857,8 +3857,8 @@ arm64_calc_VA_BITS(void)
 		} else if (ACTIVE())
 			error(FATAL, "cannot determine VA_BITS_ACTUAL: please use /proc/kcore\n");
 		else {
-			if ((string = pc->read_vmcoreinfo("NUMBER(VA_BITS_ACTUAL)"))) {
-				value = atol(string);
+			if ((string = pc->read_vmcoreinfo("NUMBER(tcr_el1_t1sz)"))) {
+				value = 64 - strtoll(string, NULL, 0);
 				free(string);
 				machdep->machspec->VA_BITS_ACTUAL = value;
 				machdep->machspec->VA_BITS = value;
===>8===

Thanks,
-Takahiro Akashi

> --pk

Bhupesh Sharma Nov. 19, 2019, 8:29 a.m. UTC | #7

On Tue, Nov 19, 2019 at 12:03 PM Prabhakar Kushwaha
<[e-mail]> wrote:
>
> Hi Akashi,
>
> On Fri, Nov 15, 2019 at 7:29 AM AKASHI Takahiro
> <[e-mail]> wrote:
> >
> > Bhupesh,
> >
> > On Fri, Nov 15, 2019 at 01:24:17AM +0530, Bhupesh Sharma wrote:
> > > Hi Akashi,
> > >
> > > On Wed, Nov 13, 2019 at 12:11 PM AKASHI Takahiro
> > > <[e-mail]> wrote:
> > > >
> > > > Hi Bhupesh,
> > > >
> > > > Do you have a corresponding patch for userspace tools,
> > > > including crash util and/or makedumpfile?
> > > > Otherwise, we can't verify that a generated core file is
> > > > correctly handled.
> > >
> > > Sure. I am still working on the crash-utility related changes, but you
> > > can find the makedumpfile changes I posted a couple of days ago here
> > > (see [0]) and the github link for the makedumpfile changes can be seen
> > > via [1].
> > >
> > > I will post the crash-util changes shortly as well.
> > > Thanks for having a look at the same.
> >
> > Thank you.
> > I have tested my kdump patch with a hacked version of crash
> > where VA_BITS_ACTUAL is calculated from tcr_el1_t1sz in vmcoreinfo.
> >
>
> I also did hack to calculate VA_BITS_ACTUAL is calculated from
> tcr_el1_t1sz in vmcoreinfo. Now i am getting error same as mentioned
> by you in other thread last month.
> https://www.mail-archive.com/[e-mail]/msg07385.html
>
> how this error was overcome?
>
> I am using
>  - crashkernel: https://github.com/crash-utility/crash.git  commit:
> babd7ae62d4e8fd6f93fd30b88040d9376522aa3
> and
>  - Linux: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> commit: af42d3466bdc8f39806b26f593604fdc54140bcb

I will post a formal change for crash-utility shortly that fixes the
same. Right now we are having issues with emails bouncing off
'[e-mail]', so my patches sent to the same are in
undelivered state at-the-moment.

For easy testing I will share the link to my github tree (off-line)
[which contains the changes] as well.

Regards,
Bhupesh

Dave Young Nov. 21, 2019, 3:20 a.m. UTC | #8

On 11/11/19 at 01:31pm, Bhupesh Sharma wrote:
> Changes since v3:
> ----------------
> - v3 can be seen here:
>   http://lists.infradead.org/pipermail/kexec/2019-March/022590.html
> - Addressed comments from James and exported TCR_EL1.T1SZ in vmcoreinfo
>   instead of PTRS_PER_PGD.
> - Added a new patch (via [PATCH 3/3]), which fixes a simple typo in
>   'Documentation/arm64/memory.rst'
> 
> Changes since v2:
> ----------------
> - v2 can be seen here:
>   http://lists.infradead.org/pipermail/kexec/2019-March/022531.html
> - Protected 'MAX_PHYSMEM_BITS' vmcoreinfo variable under CONFIG_SPARSEMEM
>   ifdef sections, as suggested by Kazu.
> - Updated vmcoreinfo documentation to add description about
>   'MAX_PHYSMEM_BITS' variable (via [PATCH 3/3]).
> 
> Changes since v1:
> ----------------
> - v1 was sent out as a single patch which can be seen here:
>   http://lists.infradead.org/pipermail/kexec/2019-February/022411.html
> 
> - v2 breaks the single patch into two independent patches:
>   [PATCH 1/2] appends 'PTRS_PER_PGD' to vmcoreinfo for arm64 arch, whereas
>   [PATCH 2/2] appends 'MAX_PHYSMEM_BITS' to vmcoreinfo in core kernel code (all archs)
> 
> This patchset primarily fixes the regression reported in user-space
> utilities like 'makedumpfile' and 'crash-utility' on arm64 architecture
> with the availability of 52-bit address space feature in underlying
> kernel. These regressions have been reported both on CPUs which don't
> support ARMv8.2 extensions (i.e. LVA, LPA) and are running newer kernels
> and also on prototype platforms (like ARMv8 FVP simulator model) which
> support ARMv8.2 extensions and are running newer kernels.
> 
> The reason for these regressions is that right now user-space tools
> have no direct access to these values (since these are not exported
> from the kernel) and hence need to rely on a best-guess method of
> determining value of 'vabits_actual' and 'MAX_PHYSMEM_BITS' supported
> by underlying kernel.
> 
> Exporting these values via vmcoreinfo will help user-land in such cases.
> In addition, as per suggestion from makedumpfile maintainer (Kazu),
> it makes more sense to append 'MAX_PHYSMEM_BITS' to
> vmcoreinfo in the core code itself rather than in arm64 arch-specific
> code, so that the user-space code for other archs can also benefit from
> this addition to the vmcoreinfo and use it as a standard way of
> determining 'SECTIONS_SHIFT' value in user-land.
> 
> Cc: Boris Petkov <[e-mail]>
> Cc: Ingo Molnar <[e-mail]>
> Cc: Thomas Gleixner <[e-mail]>
> Cc: Jonathan Corbet <[e-mail]>
> Cc: James Morse <[e-mail]>
> Cc: Mark Rutland <[e-mail]>
> Cc: Will Deacon <[e-mail]>
> Cc: Steve Capper <[e-mail]>
> Cc: Catalin Marinas <[e-mail]>
> Cc: Ard Biesheuvel <[e-mail]>
> Cc: Michael Ellerman <[e-mail]>
> Cc: Paul Mackerras <[e-mail]>
> Cc: Benjamin Herrenschmidt <[e-mail]>
> Cc: Dave Anderson <[e-mail]>
> Cc: Kazuhito Hagio <[e-mail]>
> Cc: [e-mail]
> Cc: [e-mail]
> Cc: [e-mail]
> Cc: [e-mail]
> Cc: [e-mail]
> Cc: [e-mail]
> 
> Bhupesh Sharma (3):
>   crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
>   arm64/crash_core: Export TCR_EL1.T1SZ in vmcoreinfo

Soft reminder:  the new introduced vmcoreinfo needs documentation

Please check Documentation/admin-guide/kdump/vmcoreinfo.rst

Thanks
Dave

Bhupesh Sharma Nov. 21, 2019, 4:05 a.m. UTC | #9

Hi Dave,

On Thu, Nov 21, 2019 at 8:51 AM Dave Young <[e-mail]> wrote:
>
> On 11/11/19 at 01:31pm, Bhupesh Sharma wrote:
> > Changes since v3:
> > ----------------
> > - v3 can be seen here:
> >   http://lists.infradead.org/pipermail/kexec/2019-March/022590.html
> > - Addressed comments from James and exported TCR_EL1.T1SZ in vmcoreinfo
> >   instead of PTRS_PER_PGD.
> > - Added a new patch (via [PATCH 3/3]), which fixes a simple typo in
> >   'Documentation/arm64/memory.rst'
> >
> > Changes since v2:
> > ----------------
> > - v2 can be seen here:
> >   http://lists.infradead.org/pipermail/kexec/2019-March/022531.html
> > - Protected 'MAX_PHYSMEM_BITS' vmcoreinfo variable under CONFIG_SPARSEMEM
> >   ifdef sections, as suggested by Kazu.
> > - Updated vmcoreinfo documentation to add description about
> >   'MAX_PHYSMEM_BITS' variable (via [PATCH 3/3]).
> >
> > Changes since v1:
> > ----------------
> > - v1 was sent out as a single patch which can be seen here:
> >   http://lists.infradead.org/pipermail/kexec/2019-February/022411.html
> >
> > - v2 breaks the single patch into two independent patches:
> >   [PATCH 1/2] appends 'PTRS_PER_PGD' to vmcoreinfo for arm64 arch, whereas
> >   [PATCH 2/2] appends 'MAX_PHYSMEM_BITS' to vmcoreinfo in core kernel code (all archs)
> >
> > This patchset primarily fixes the regression reported in user-space
> > utilities like 'makedumpfile' and 'crash-utility' on arm64 architecture
> > with the availability of 52-bit address space feature in underlying
> > kernel. These regressions have been reported both on CPUs which don't
> > support ARMv8.2 extensions (i.e. LVA, LPA) and are running newer kernels
> > and also on prototype platforms (like ARMv8 FVP simulator model) which
> > support ARMv8.2 extensions and are running newer kernels.
> >
> > The reason for these regressions is that right now user-space tools
> > have no direct access to these values (since these are not exported
> > from the kernel) and hence need to rely on a best-guess method of
> > determining value of 'vabits_actual' and 'MAX_PHYSMEM_BITS' supported
> > by underlying kernel.
> >
> > Exporting these values via vmcoreinfo will help user-land in such cases.
> > In addition, as per suggestion from makedumpfile maintainer (Kazu),
> > it makes more sense to append 'MAX_PHYSMEM_BITS' to
> > vmcoreinfo in the core code itself rather than in arm64 arch-specific
> > code, so that the user-space code for other archs can also benefit from
> > this addition to the vmcoreinfo and use it as a standard way of
> > determining 'SECTIONS_SHIFT' value in user-land.
> >
> > Cc: Boris Petkov <[e-mail]>
> > Cc: Ingo Molnar <[e-mail]>
> > Cc: Thomas Gleixner <[e-mail]>
> > Cc: Jonathan Corbet <[e-mail]>
> > Cc: James Morse <[e-mail]>
> > Cc: Mark Rutland <[e-mail]>
> > Cc: Will Deacon <[e-mail]>
> > Cc: Steve Capper <[e-mail]>
> > Cc: Catalin Marinas <[e-mail]>
> > Cc: Ard Biesheuvel <[e-mail]>
> > Cc: Michael Ellerman <[e-mail]>
> > Cc: Paul Mackerras <[e-mail]>
> > Cc: Benjamin Herrenschmidt <[e-mail]>
> > Cc: Dave Anderson <[e-mail]>
> > Cc: Kazuhito Hagio <[e-mail]>
> > Cc: [e-mail]
> > Cc: [e-mail]
> > Cc: [e-mail]
> > Cc: [e-mail]
> > Cc: [e-mail]
> > Cc: [e-mail]
> >
> > Bhupesh Sharma (3):
> >   crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
> >   arm64/crash_core: Export TCR_EL1.T1SZ in vmcoreinfo
>
> Soft reminder:  the new introduced vmcoreinfo needs documentation
>
> Please check Documentation/admin-guide/kdump/vmcoreinfo.rst

Sure, will send a v5 to address the same.

Thanks,
Bhupesh