Re: [PATCH 2/5] x86/sgx: Add kernel-doc descriptions for params passed to vDSO user handler

Jarkko Sakkinen
2025-11-19T02:28:07Z

On Wed, Nov 12, 2025 at 08:07:05AM -0800, Sean Christopherson wrote:
> Add kernel-doc markup for the register parameters passed by the vDSO blob
> to the user handler to suppress build warnings, e.g.
>
> WARNING: arch/x86/include/uapi/asm/sgx.h:157 function parameter 'r8' not
> described in 'sgx_enclave_user_handler_t'
>
> Call out that except for RSP, the registers are undefined on asynchronous
> exits as far as the vDSO ABI is concerned. E.g. the vDSO's exception
> handler clobbers RDX, RDI, and RSI, and the kernel doesn't guarantee that
> R8 or R9 will be zero (the synthetic value loaded by the CPU).
>
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Closes: https://lore.kernel.org/all/20251106145506.145fc620@canb.auug.org.au
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/include/uapi/asm/sgx.h | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
> index a438ea43bfd1..0d408f001ac6 100644
> --- a/arch/x86/include/uapi/asm/sgx.h
> +++ b/arch/x86/include/uapi/asm/sgx.h
> @@ -143,6 +143,12 @@ struct sgx_enclave_run;
> /**
> * typedef sgx_enclave_user_handler_t - Exit handler function accepted by
> * __vdso_sgx_enter_enclave()
> + * @rdi: RDI at the time of EEXIT, undefined on AEX
> + * @rsi: RSI at the time of EEXIT, undefined on AEX
> + * @rdx: RDX at the time of EEXIT, undefined on AEX
> + * @rsp: RSP (untrusted) at the time of EEXIT or AEX
> + * @r8: R8 at the time of EEXIT, undefined on AEX
> + * @r9: R9 at the time of EEXIT, undefined on AEX
> * @run: The run instance given by the caller
> *
> * The register parameters contain the snapshot of their values at enclave
> --
> 2.51.2.1041.gc1ab5b90ca-goog
>

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko