From bcfdf53da8d7eacd386624079b383fb83e4aa553 Mon Sep 17 00:00:00 2001
From: Dave Tucker <dave@dtucker.co.uk>
Date: Tue, 17 May 2022 10:02:24 +0200
Subject: [PATCH] bpf: Add PtRegs wrapper
This adds a portable wrapper around pt_regs and user_pt_regs.
It makes writing Raw Tracepoint or KProbe programs easier when the
arguments are one of these types while also ensuring code is portable
across architectures
Signed-off-by: Dave Tucker <dave@dtucker.co.uk>
---
bpf/aya-bpf/src/args.rs | 26 ++++++++++++++++++++++++++
bpf/aya-bpf/src/lib.rs | 1 +
2 files changed, 27 insertions(+)
diff --git a/bpf/aya-bpf/src/args.rs b/bpf/aya-bpf/src/args.rs
index 42bfad9f..c919576a 100644
--- a/bpf/aya-bpf/src/args.rs
+++ b/bpf/aya-bpf/src/args.rs
@@ -56,6 +56,32 @@ unsafe_impl_from_btf_argument!(i64);
unsafe_impl_from_btf_argument!(usize);
unsafe_impl_from_btf_argument!(isize);
+pub struct PtRegs {
+ regs: *mut pt_regs,
+}
+
+/// A portable wrapper around pt_regs and user_pt_regs.
+impl PtRegs {
+ pub fn new(regs: *mut pt_regs) -> Self {
+ PtRegs { regs }
+ }
+
+ /// Returns the value of the register used to pass arg `n`.
+ pub fn arg<T: FromPtRegs>(&self, n: usize) -> Option<T> {
+ T::from_argument(unsafe { &*self.regs }, n)
+ }
+
+ /// Returns the value of the register used to pass the return value.
+ pub fn ret<T: FromPtRegs>(&self) -> Option<T> {
+ T::from_retval(unsafe { &*self.regs })
+ }
+
+ /// Returns a pointer to the wrapped value.
+ pub fn as_ptr(&self) -> *mut pt_regs {
+ self.regs
+ }
+}
+
/// A trait that indicates a valid type for an argument which can be coerced from
/// a pt_regs context.
///
diff --git a/bpf/aya-bpf/src/lib.rs b/bpf/aya-bpf/src/lib.rs
index 688708d1..e62f10bd 100644
--- a/bpf/aya-bpf/src/lib.rs
+++ b/bpf/aya-bpf/src/lib.rs
@@ -5,6 +5,7 @@
pub use aya_bpf_bindings::bindings;
mod args;
+pub use args::PtRegs;
pub mod helpers;
pub mod maps;
pub mod programs;