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feat(ctx): add ctx.load_bytes for copying context memory into event buffers #52

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Merged
maheshbhatiya73 merged 1 commit into from
Mar 12, 2026
Merged

feat(ctx): add ctx.load_bytes for copying context memory into event buffers #52

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1 change: 1 addition & 0 deletions src/ast/unit.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -223,6 +223,7 @@ impl ProgramKind {
LoadI16,
LoadI32,
LoadI64,
LoadBytes,
GetPidTgid,
GetUidGid,
GetCurrentComm,
Expand Down
24 changes: 22 additions & 2 deletions src/emit/ebpf_c/tracepoint.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -196,15 +196,23 @@ pub fn emit_tracepoint(out: &mut String, unit: &UnitIr, sec: &str) -> Result<(),
if let Some(operand) = inst.operands.get(0) {
let ptr = format_operand(operand);
let res = res_name.unwrap();
writeln!(out, " {} = *((__u64 *)(void *)({}));", res, ptr).map_err(err)?;
writeln!(out, " {} = *((__u64 *)(void *)({}));", res, ptr)
.map_err(err)?;
}
}

Opcode::Store { size } => {
if inst.operands.len() >= 2 {
let ptr = format_operand(&inst.operands[0]);
let val = format_operand(&inst.operands[1]);
writeln!(out, " *((__u{} *)(void *)({})) = {};", size * 8, ptr, val).map_err(err)?;
writeln!(
out,
" *((__u{} *)(void *)({})) = {};",
size * 8,
ptr,
val
)
.map_err(err)?;
}
}

Expand Down Expand Up @@ -358,6 +366,18 @@ pub fn emit_tracepoint(out: &mut String, unit: &UnitIr, sec: &str) -> Result<(),
writeln!(out, " bpf_ringbuf_submit({}, 0);", ptr).map_err(err)?;
}
}
Opcode::CopyCtxToMem { offset, size } => {
let dest = match &inst.operands[0] {
Operand::Var(v) => format!("v{}", v.0),
_ => panic!("CopyCtxToMem expects dest var"),
};

writeln!(
out,
"bpf_probe_read_kernel({}, {}, (void *)ctx + {});",
dest, size, offset
);
}
}

inst_index += 1;
Expand Down
17 changes: 9 additions & 8 deletions src/ir/ctx.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,28 +11,28 @@ pub enum CtxMethod {
LoadI16,
LoadI32,
LoadI64,
LoadBytes,

// ================================
// Process / task metadata helpers
// ================================
GetPidTgid, // bpf_get_current_pid_tgid (helper 14)
GetUidGid, // bpf_get_current_uid_gid
GetCurrentComm, // bpf_get_current_comm
GetCurrentTask, // bpf_get_current_task
GetPidTgid, // bpf_get_current_pid_tgid (helper 14)
GetUidGid, // bpf_get_current_uid_gid
GetCurrentComm, // bpf_get_current_comm
GetCurrentTask, // bpf_get_current_task

// ================================
// Time helpers
// ================================
GetKtimeNs, // bpf_ktime_get_ns
GetKtimeNs, // bpf_ktime_get_ns

// ================================
// Memory probe helpers
// ================================
ProbeReadUserStr, // bpf_probe_read_user_str (helper 202)
ProbeReadUserStr, // bpf_probe_read_user_str (helper 202)
ProbeReadKernelStr, // bpf_probe_read_kernel_str (helper 204)
}


impl CtxMethod {
pub fn from_str(name: &str) -> Option<Self> {
match name {
Expand All @@ -45,6 +45,7 @@ impl CtxMethod {
"load_i16" => Some(Self::LoadI16),
"load_i32" => Some(Self::LoadI32),
"load_i64" => Some(Self::LoadI64),
"load_bytes" => Some(Self::LoadBytes),

// Metadata helpers
"get_pid_tgid" => Some(Self::GetPidTgid),
Expand All @@ -62,4 +63,4 @@ impl CtxMethod {
_ => None,
}
}
}
}
2 changes: 2 additions & 0 deletions src/ir/instruction.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,8 @@ pub enum Opcode {
LoadCtx { offset: i32, size: u8 },
LoadPacket { offset: i32, size: u8 },

CopyCtxToMem { offset: i32, size: u32 },

// checks
NullCheck,

Expand Down
82 changes: 68 additions & 14 deletions src/ir/unit.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -72,7 +72,14 @@ impl UnitIr {
};

for stmt in &unit.body {
lower_statement(stmt, &mut ctx, &mut ir, &mut current_block, events, event_decls)?;
lower_statement(
stmt,
&mut ctx,
&mut ir,
&mut current_block,
events,
event_decls,
)?;
}

ir.blocks.push(current_block);
Expand Down Expand Up @@ -117,6 +124,7 @@ fn lower_ctx_helper(
| CtxMethod::LoadI16
| CtxMethod::LoadI32
| CtxMethod::LoadI64
| CtxMethod::LoadBytes
| CtxMethod::ProbeReadUserStr
| CtxMethod::ProbeReadKernelStr => {
return Err(LoweringError::UnitLowering(format!(
Expand Down Expand Up @@ -194,7 +202,8 @@ fn lower_statement(
)));
}

let key = lower_expr(&call.arg[0], ctx, ir, block, events, event_decls)?;
let key =
lower_expr(&call.arg[0], ctx, ir, block, events, event_decls)?;
let result = ir.alloc_var(crate::ast::Type::U64);

block.instructions.push(Instruction {
Expand Down Expand Up @@ -384,7 +393,7 @@ fn lower_statement(
// Handle field assignment like evt.pid = value
// First, get the base pointer/variable
let base_operand = lower_expr(base, ctx, ir, block, events, event_decls)?;

// Get the variable ID (should be a pointer from reserve)
let base_var = if let Operand::Var(v) = base_operand {
v
Expand All @@ -397,20 +406,23 @@ fn lower_statement(
// Look up field offset across all events
let mut field_offset: Option<u32> = None;
for (_, event_decl) in event_decls {
if let Some(offset) = crate::sema::event::compute_field_offset(event_decl, field) {
if let Some(offset) =
crate::sema::event::compute_field_offset(event_decl, field)
{
field_offset = Some(offset);
break;
}
}

let _offset = field_offset.ok_or_else(|| {
LoweringError::UnitLowering(format!("Unknown field: {}", field))
})?;

// For now, we only support simple field assignments (no compound ops on fields)
if !matches!(assign.op, crate::ast::AssignmentOp::Assign) {
return Err(LoweringError::UnitLowering(
"Compound assignment operators not supported on struct fields".to_string(),
"Compound assignment operators not supported on struct fields"
.to_string(),
));
}

Expand Down Expand Up @@ -589,7 +601,8 @@ fn lower_expr(
)));
}

let offset_expr = lower_expr(&call.arg[0], ctx, ir, block, events, event_decls)?;
let offset_expr =
lower_expr(&call.arg[0], ctx, ir, block, events, event_decls)?;
let offset = match offset_expr {
Operand::Immediate(n) => n as i32,
_ => {
Expand Down Expand Up @@ -639,7 +652,8 @@ fn lower_expr(
}

let dest = lower_expr(&call.arg[0], ctx, ir, block, events, event_decls)?;
let size_expr = lower_expr(&call.arg[1], ctx, ir, block, events, event_decls)?;
let size_expr =
lower_expr(&call.arg[1], ctx, ir, block, events, event_decls)?;
let src = lower_expr(&call.arg[2], ctx, ir, block, events, event_decls)?;

let size = match size_expr {
Expand Down Expand Up @@ -672,7 +686,8 @@ fn lower_expr(
}

let dest = lower_expr(&call.arg[0], ctx, ir, block, events, event_decls)?;
let size_expr = lower_expr(&call.arg[1], ctx, ir, block, events, event_decls)?;
let size_expr =
lower_expr(&call.arg[1], ctx, ir, block, events, event_decls)?;
let src = lower_expr(&call.arg[2], ctx, ir, block, events, event_decls)?;

let size = match size_expr {
Expand All @@ -695,6 +710,46 @@ fn lower_expr(
Ok(Operand::Var(result))
}

CtxMethod::LoadBytes => {
if call.arg.len() != 3 {
return Err(LoweringError::UnitLowering(
"ctx.load_bytes expects (offset, dest, size)".to_string(),
));
}

let offset_expr =
lower_expr(&call.arg[0], ctx, ir, block, events, event_decls)?;
let dest = lower_expr(&call.arg[1], ctx, ir, block, events, event_decls)?;
let size_expr =
lower_expr(&call.arg[2], ctx, ir, block, events, event_decls)?;

let offset = match offset_expr {
Operand::Immediate(n) => n as i32,
_ => {
return Err(LoweringError::UnitLowering(
"offset must be immediate".to_string(),
))
}
};

let size = match size_expr {
Operand::Immediate(n) => n as u32,
_ => {
return Err(LoweringError::UnitLowering(
"size must be immediate".to_string(),
))
}
};

block.instructions.push(Instruction {
result: ir.alloc_var(crate::ast::Type::U64),
opcode: Opcode::CopyCtxToMem { offset, size },
operands: vec![dest.clone()],
result_type: crate::ast::Type::U64,
});

Ok(dest)
}
// ctx helper methods (0 args)
_ => {
if !call.arg.is_empty() {
Expand Down Expand Up @@ -908,7 +963,7 @@ fn lower_expr(
ExprKind::FieldAccess { base, field } => {
// Handle field access like evt.filename
let base_operand = lower_expr(base, ctx, ir, block, events, event_decls)?;

// Get the variable ID (should be a pointer from reserve)
let base_var = if let Operand::Var(v) = base_operand {
v
Expand All @@ -926,10 +981,9 @@ fn lower_expr(
break;
}
}

let _offset = field_offset.ok_or_else(|| {
LoweringError::UnitLowering(format!("Unknown field: {}", field))
})?;

let _offset = field_offset
.ok_or_else(|| LoweringError::UnitLowering(format!("Unknown field: {}", field)))?;

// Create a load instruction from the field
// TODO: Currently we load from base pointer with fixed size
Expand Down
2 changes: 1 addition & 1 deletion src/lexer/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -132,7 +132,7 @@ impl<'src> Lexer<'src> {
"guard" => TokenKind::KeywordGuard,
"heap" => TokenKind::KeywordHeap,
"event" => TokenKind::KeywordEvent,
"bytes" => TokenKind::KeywordBytes, // ADD THIS
"bytes" => TokenKind::KeywordBytes,
"u32" => TokenKind::TypeU32,
"u64" => TokenKind::TypeU64,
"i32" => TokenKind::TypeI32,
Expand Down
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