linux.git/arch/arm64/include/asm/stacktrace, branch v6.0

arm64: Update 'unwinder howto'

2022-07-27T17:18:47+00:00

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 
Reviewed-by: Kalesh Singh 
Tested-by: Kalesh Singh 
Reviewed-by: Oliver Upton 
Link: https://lore.kernel.org/r/20220727142906.1856759-7-maz@kernel.org

KVM: arm64: Move nVHE-only helpers into kvm/stacktrace.c

2022-07-27T17:18:03+00:00

kvm_nvhe_stack_kern_va() only makes sense as part of the nVHE
unwinder, so simply move it there.

Signed-off-by: Marc Zyngier 
Reviewed-by: Kalesh Singh 
Tested-by: Kalesh Singh 
Reviewed-by: Oliver Upton 
Link: https://lore.kernel.org/r/20220727142906.1856759-5-maz@kernel.org

KVM: arm64: Make unwind()/on_accessible_stack() per-unwinder functions

2022-07-27T17:18:03+00:00

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 
Reviewed-by: Kalesh Singh 
Tested-by: Kalesh Singh 
Reviewed-by: Oliver Upton 
Link: https://lore.kernel.org/r/20220727142906.1856759-4-maz@kernel.org

KVM: arm64: Move nVHE stacktrace unwinding into its own compilation unit

2022-07-27T17:18:03+00:00

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 
Reviewed-by: Kalesh Singh 
Tested-by: Kalesh Singh 
Reviewed-by: Oliver Upton 
Link: https://lore.kernel.org/r/20220727142906.1856759-3-maz@kernel.org

KVM: arm64: Implement protected nVHE hyp stack unwinder

2022-07-26T09:51:28+00:00

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 
Reviewed-by: Fuad Tabba 
Tested-by: Fuad Tabba 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20220726073750.3219117-17-kaleshsingh@google.com

KVM: arm64: Stub implementation of pKVM HYP stack unwinder

2022-07-26T09:51:06+00:00

Add some stub implementations of protected nVHE stack unwinder, for
building. These are implemented later in this series.

Signed-off-by: Kalesh Singh 
Reviewed-by: Fuad Tabba 
Tested-by: Fuad Tabba 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20220726073750.3219117-15-kaleshsingh@google.com

KVM: arm64: Introduce hyp_dump_backtrace()

2022-07-26T09:49:50+00:00

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]:  [] __kvm_nvhe_hyp_panic+0xac/0xf8
[  101.499045] kvm [377]:  [] __kvm_nvhe_hyp_panic_bad_stack+0x10/0x10
[  101.499498] kvm [377]:  [] __kvm_nvhe_recursive_death+0x24/0x34
. . .
[  101.524929] kvm [377]:  [] __kvm_nvhe_recursive_death+0x24/0x34
[  101.525062] kvm [377]:  [] __kvm_nvhe_recursive_death+0x24/0x34
[  101.525195] kvm [377]:  [] __kvm_nvhe___kvm_vcpu_run+0x30/0x40c
[  101.525333] kvm [377]:  [] __kvm_nvhe_handle___kvm_vcpu_run+0x30/0x48
[  101.525468] kvm [377]:  [] __kvm_nvhe_handle_trap+0xc4/0x128
[  101.525602] kvm [377]:  [] __kvm_nvhe___host_exit+0x64/0x64
[  101.525745] kvm [377]: ---[ end nVHE call trace ]---

Signed-off-by: Kalesh Singh 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20220726073750.3219117-12-kaleshsingh@google.com

KVM: arm64: Implement non-protected nVHE hyp stack unwinder

2022-07-26T09:49:39+00:00

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 
Reviewed-by: Fuad Tabba 
Tested-by: Fuad Tabba 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20220726073750.3219117-11-kaleshsingh@google.com

KVM: arm64: Stub implementation of non-protected nVHE HYP stack unwinder

2022-07-26T09:49:16+00:00

Add stub implementations of non-protected nVHE stack unwinder, for
building. These are implemented later in this series.

Signed-off-by: Kalesh Singh 
Reviewed-by: Fuad Tabba 
Tested-by: Fuad Tabba 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20220726073750.3219117-9-kaleshsingh@google.com

arm64: stacktrace: Add description of stacktrace/common.h

2022-07-26T09:48:54+00:00

Add brief description on how to use stacktrace/common.h to implement
a stack unwinder.

Signed-off-by: Kalesh Singh 
Reviewed-by: Fuad Tabba 
Signed-off-by: Marc Zyngier 
Link: https://lore.kernel.org/r/20220726073750.3219117-7-kaleshsingh@google.com