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15 Commits

Author SHA1 Message Date
Marc Zyngier
a4c750e232 arm64: Update 'unwinder howto' 
Implementing a new unwinder is a bit more involved than writing
a couple of helpers, so let's not lure the reader into a false
sense of comfort. Instead, let's point out what they should
call into, and what sort of parameter they need to provide.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20220727142906.1856759-7-maz@kernel.org
 2022-07-27 18:18:47 +01:00
Marc Zyngier
0e773da1e6 KVM: arm64: Move nVHE-only helpers into kvm/stacktrace.c 
kvm_nvhe_stack_kern_va() only makes sense as part of the nVHE
unwinder, so simply move it there.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20220727142906.1856759-5-maz@kernel.org
 2022-07-27 18:18:03 +01:00
Marc Zyngier
4e00532f37 KVM: arm64: Make unwind()/on_accessible_stack() per-unwinder functions 
Having multiple versions of on_accessible_stack() (one per unwinder)
makes it very hard to reason about what is used where due to the
complexity of the various includes, the forward declarations, and
the reliance on everything being 'inline'.

Instead, move the code back where it should be. Each unwinder
implements:

- on_accessible_stack() as well as the helpers it depends on,

- unwind()/unwind_next(), as they pass on_accessible_stack as
  a parameter to unwind_next_common() (which is the only common
  code here)

This hardly results in any duplication, and makes it much
easier to reason about the code.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20220727142906.1856759-4-maz@kernel.org
 2022-07-27 18:18:03 +01:00
Marc Zyngier
9f5fee05f6 KVM: arm64: Move nVHE stacktrace unwinding into its own compilation unit 
The unwinding code doesn't really belong to the exit handling
code. Instead, move it to a file (conveniently named stacktrace.c
to confuse the reviewer), and move all the stacktrace-related
stuff there.

It will be joined by more code very soon.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Tested-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20220727142906.1856759-3-maz@kernel.org
 2022-07-27 18:18:03 +01:00
Kalesh Singh
75e9459e48 KVM: arm64: Implement protected nVHE hyp stack unwinder 
Implements the common framework necessary for unwind() to work in
the protected nVHE context:
   - on_accessible_stack()
   - on_overflow_stack()
   - unwind_next()

Protected nVHE unwind() is used to unwind and save the hyp stack
addresses to the shared stacktrace buffer. The host reads the
entries in this buffer, symbolizes and dumps the stacktrace (later
patch in the series).

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-17-kaleshsingh@google.com
 2022-07-26 10:51:28 +01:00
Kalesh Singh
25aa73b6db KVM: arm64: Stub implementation of pKVM HYP stack unwinder 
Add some stub implementations of protected nVHE stack unwinder, for
building. These are implemented later in this series.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-15-kaleshsingh@google.com
 2022-07-26 10:51:06 +01:00
Kalesh Singh
314a61dc31 KVM: arm64: Introduce hyp_dump_backtrace() 
In non-protected nVHE mode, unwinds and dumps the hypervisor backtrace
from EL1. This is possible beacause the host can directly access the
hypervisor stack pages in non-protected mode.

The nVHE backtrace is dumped on hyp_panic(), before panicking the host.

[  101.498183] kvm [377]: nVHE call trace:
[  101.498363] kvm [377]:  [<ffff8000090a6570>] __kvm_nvhe_hyp_panic+0xac/0xf8
[  101.499045] kvm [377]:  [<ffff8000090a65cc>] __kvm_nvhe_hyp_panic_bad_stack+0x10/0x10
[  101.499498] kvm [377]:  [<ffff8000090a61e4>] __kvm_nvhe_recursive_death+0x24/0x34
. . .
[  101.524929] kvm [377]:  [<ffff8000090a61e4>] __kvm_nvhe_recursive_death+0x24/0x34
[  101.525062] kvm [377]:  [<ffff8000090a61e4>] __kvm_nvhe_recursive_death+0x24/0x34
[  101.525195] kvm [377]:  [<ffff8000090a5de4>] __kvm_nvhe___kvm_vcpu_run+0x30/0x40c
[  101.525333] kvm [377]:  [<ffff8000090a8b64>] __kvm_nvhe_handle___kvm_vcpu_run+0x30/0x48
[  101.525468] kvm [377]:  [<ffff8000090a88b8>] __kvm_nvhe_handle_trap+0xc4/0x128
[  101.525602] kvm [377]:  [<ffff8000090a7864>] __kvm_nvhe___host_exit+0x64/0x64
[  101.525745] kvm [377]: ---[ end nVHE call trace ]---

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-12-kaleshsingh@google.com
 2022-07-26 10:49:50 +01:00
Kalesh Singh
db129d486e KVM: arm64: Implement non-protected nVHE hyp stack unwinder 
Implements the common framework necessary for unwind() to work
for non-protected nVHE mode:
    - on_accessible_stack()
    - on_overflow_stack()
    - unwind_next()

Non-protected nVHE unwind() is used to unwind and dump the hypervisor
stacktrace by the host in EL1

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-11-kaleshsingh@google.com
 2022-07-26 10:49:39 +01:00
Kalesh Singh
573e1e8275 KVM: arm64: Stub implementation of non-protected nVHE HYP stack unwinder 
Add stub implementations of non-protected nVHE stack unwinder, for
building. These are implemented later in this series.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-9-kaleshsingh@google.com
 2022-07-26 10:49:16 +01:00
Kalesh Singh
051ece6758 arm64: stacktrace: Add description of stacktrace/common.h 
Add brief description on how to use stacktrace/common.h to implement
a stack unwinder.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-7-kaleshsingh@google.com
 2022-07-26 10:48:54 +01:00
Kalesh Singh
f51e714674 arm64: stacktrace: Factor out common unwind() 
Move unwind() to stacktrace/common.h, and as a result
the kernel unwind_next() to asm/stacktrace.h. This allow
reusing unwind() in the implementation of the nVHE HYP
stack unwinder, later in the series.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-6-kaleshsingh@google.com
 2022-07-26 10:48:43 +01:00
Kalesh Singh
5b1b08619f arm64: stacktrace: Handle frame pointer from different address spaces 
The unwinder code is made reusable so that it can be used to
unwind various types of stacks. One usecase is unwinding the
nVHE hyp stack from the host (EL1) in non-protected mode. This
means that the unwinder must be able to translate HYP stack
addresses to kernel addresses.

Add a callback (stack_trace_translate_fp_fn) to allow specifying
the translation function.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-5-kaleshsingh@google.com
 2022-07-26 10:48:32 +01:00
Kalesh Singh
be63c647fd arm64: stacktrace: Factor out unwind_next_common() 
Move common unwind_next logic to stacktrace/common.h. This allows
reusing the code in the implementation the nVHE hypervisor stack
unwinder, later in this series.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-4-kaleshsingh@google.com
 2022-07-26 10:48:20 +01:00
Kalesh Singh
15a59f19a0 arm64: stacktrace: Factor out on_accessible_stack_common() 
Move common on_accessible_stack checks to stacktrace/common.h. This is
used in the implementation of the nVHE hypervisor unwinder later in
this series.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-3-kaleshsingh@google.com
 2022-07-26 10:48:09 +01:00
Kalesh Singh
6bf212c89c arm64: stacktrace: Add shared header for common stack unwinding code 
In order to reuse the arm64 stack unwinding logic for the nVHE
hypervisor stack, move the common code to a shared header
(arch/arm64/include/asm/stacktrace/common.h).

The nVHE hypervisor cannot safely link against kernel code, so we
make use of the shared header to avoid duplicated logic later in
this series.

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-2-kaleshsingh@google.com
 2022-07-26 10:47:14 +01:00