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2022-07-27arm64: Update 'unwinder howto'Marc Zyngier
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
2022-07-27KVM: arm64: Move nVHE-only helpers into kvm/stacktrace.cMarc Zyngier
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
2022-07-27KVM: arm64: Make unwind()/on_accessible_stack() per-unwinder functionsMarc Zyngier
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
2022-07-27KVM: arm64: Move nVHE stacktrace unwinding into its own compilation unitMarc Zyngier
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
2022-07-26KVM: arm64: Implement protected nVHE hyp stack unwinderKalesh Singh
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
2022-07-26KVM: arm64: Stub implementation of pKVM HYP stack unwinderKalesh Singh
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
2022-07-26KVM: arm64: Introduce hyp_dump_backtrace()Kalesh Singh
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
2022-07-26KVM: arm64: Implement non-protected nVHE hyp stack unwinderKalesh Singh
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
2022-07-26KVM: arm64: Stub implementation of non-protected nVHE HYP stack unwinderKalesh Singh
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
2022-07-26arm64: stacktrace: Add description of stacktrace/common.hKalesh Singh
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
2022-07-26arm64: stacktrace: Factor out common unwind()Kalesh Singh
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
2022-07-26arm64: stacktrace: Handle frame pointer from different address spacesKalesh Singh
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
2022-07-26arm64: stacktrace: Factor out unwind_next_common()Kalesh Singh
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
2022-07-26arm64: stacktrace: Factor out on_accessible_stack_common()Kalesh Singh
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
2022-07-26arm64: stacktrace: Add shared header for common stack unwinding codeKalesh Singh
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