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bpf, arm64: Support Exceptions #6373

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bpf, arm64: Support Exceptions #6373

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Pull request for series with
subject: bpf, arm64: Support Exceptions
version: 3
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107

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Upstream branch: 994ff2f
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: 1581e51
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: 943b043
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: 6fb3f72
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: a68b50f
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: 2a79690
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: df9705e
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: 7e42863
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: 169e650
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: 1159d27
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: 1159d27
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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Upstream branch: 1159d27
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

@puranjaymohan
arm64: stacktrace: Implement arch_bpf_stack_walk() for the BPF JIT
efe8b74 
This will be used by bpf_throw() to unwind till the program marked as
exception boundary and run the callback with the stack of the main
program.

This is required for supporting BPF exceptions on ARM64.

Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
@puranjaymohan
bpf, arm64: support exceptions
82e92a3 
The prologue generation code has been modified to make the callback
program use the stack of the program marked as exception boundary where
callee-saved registers are already pushed.

As the bpf_throw function never returns, if it clobbers any callee-saved
registers, they would remain clobbered. So, the prologue of the
exception-boundary program is modified to push R23 and R24 as well,
which the callback will then recover in its epilogue.

The Procedure Call Standard for the Arm 64-bit Architecture[1] states
that registers r19 to r28 should be saved by the callee. BPF programs on
ARM64 already save all callee-saved registers except r23 and r24. This
patch adds an instruction in prologue of the  program to save these
two registers and another instruction in the epilogue to recover them.

These extra instructions are only added if bpf_throw() is used. Otherwise
the emitted prologue/epilogue remains unchanged.

[1] https://github.com/ARM-software/abi-aa/blob/main/aapcs64/aapcs64.rst

Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
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Upstream branch: a4561f5
series: https://patchwork.kernel.org/project/netdevbpf/list/?series=822107
version: 3

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At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=784973 expired. Closing PR.

@kernel-patches-daemon-bpf kernel-patches-daemon-bpf bot deleted the series/784973=>bpf-next branch February 17, 2024 21:00
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