arch/loongarch/net/bpf_jit.c

File Facts

System

Linux kernel

Corpus path

arch/loongarch/net/bpf_jit.c

Extension

.c

Size

64985 bytes

Lines

2370

Domain

Architecture Layer

Bucket

arch/loongarch

Inferred role

Architecture Layer: implementation source

Status

source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

• CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.
• Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Allocates kernel memory; connect allocation flags and lifetime to context constraints.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/memory.h
• bpf_jit.h

Detected Declarations

• function prepare_bpf_tail_call_cnt
• function build_prologue
• function __build_epilogue
• function build_epilogue
• function bpf_jit_supports_kfunc_call
• function bpf_jit_supports_far_kfunc_call
• function emit_bpf_tail_call
• function emit_store_stack_imm64
• function emit_atomic_rmw
• function emit_atomic_ld_st
• function is_signed_bpf_cond
• function ex_handler_bpf
• function add_exception_handler
• function build_insn
• function build_body
• function jit_fill_hole
• function validate_code
• function validate_ctx
• function emit_jump_and_link
• function emit_jump_or_nops
• function emit_call
• function bpf_arch_text_poke
• function bpf_arch_text_invalidate
• function store_args
• function restore_args
• function restore_stk_args
• function invoke_bpf_prog
• function invoke_bpf
• function arch_free_bpf_trampoline
• function arch_protect_bpf_trampoline
• function sign_extend
• function __arch_prepare_bpf_trampoline
• function arch_prepare_bpf_trampoline
• function arch_bpf_trampoline_size
• function bpf_jit_free
• function JIT
• function bpf_jit_bypass_spec_v1
• function bpf_jit_bypass_spec_v4
• function bpf_jit_supports_arena
• function bpf_jit_supports_fsession
• function bpf_jit_supports_subprog_tailcalls

Annotated Snippet

switch (BPF_SIZE(insn->code)) {
		case BPF_B:
			if (!cpu_has_lam_bh) {
				pr_err_once("bpf-jit: amadd.b instruction is not supported\n");
				return -EINVAL;
			}
			emit_insn(ctx, amaddb, t2, t1, src);
			break;
		case BPF_H:
			if (!cpu_has_lam_bh) {
				pr_err_once("bpf-jit: amadd.h instruction is not supported\n");
				return -EINVAL;
			}
			emit_insn(ctx, amaddh, t2, t1, src);
			break;
		case BPF_W:
			emit_insn(ctx, amaddw, t2, t1, src);
			break;
		case BPF_DW:
			emit_insn(ctx, amaddd, t2, t1, src);
			break;
		}
		break;
	case BPF_AND:
		if (isdw)
			emit_insn(ctx, amandd, t2, t1, src);
		else
			emit_insn(ctx, amandw, t2, t1, src);
		break;
	case BPF_OR:
		if (isdw)
			emit_insn(ctx, amord, t2, t1, src);
		else
			emit_insn(ctx, amorw, t2, t1, src);
		break;
	case BPF_XOR:
		if (isdw)
			emit_insn(ctx, amxord, t2, t1, src);
		else
			emit_insn(ctx, amxorw, t2, t1, src);
		break;
	/* src = atomic_fetch_<op>(dst + off, src) */
	case BPF_ADD | BPF_FETCH:
		switch (BPF_SIZE(insn->code)) {
		case BPF_B:
			if (!cpu_has_lam_bh) {
				pr_err_once("bpf-jit: amadd.b instruction is not supported\n");
				return -EINVAL;
			}
			emit_insn(ctx, amaddb, src, t1, t3);
			emit_zext_32(ctx, src, true);
			break;
		case BPF_H:
			if (!cpu_has_lam_bh) {
				pr_err_once("bpf-jit: amadd.h instruction is not supported\n");
				return -EINVAL;
			}
			emit_insn(ctx, amaddh, src, t1, t3);
			emit_zext_32(ctx, src, true);
			break;
		case BPF_W:
			emit_insn(ctx, amaddw, src, t1, t3);
			emit_zext_32(ctx, src, true);
			break;
		case BPF_DW:
			emit_insn(ctx, amaddd, src, t1, t3);
			break;
		}
		break;
	case BPF_AND | BPF_FETCH:
		if (isdw) {
			emit_insn(ctx, amandd, src, t1, t3);
		} else {
			emit_insn(ctx, amandw, src, t1, t3);
			emit_zext_32(ctx, src, true);
		}
		break;
	case BPF_OR | BPF_FETCH:
		if (isdw) {
			emit_insn(ctx, amord, src, t1, t3);
		} else {
			emit_insn(ctx, amorw, src, t1, t3);
			emit_zext_32(ctx, src, true);
		}
		break;
	case BPF_XOR | BPF_FETCH:
		if (isdw) {
			emit_insn(ctx, amxord, src, t1, t3);
		} else {
			emit_insn(ctx, amxorw, src, t1, t3);

Annotation

• Immediate include surface: `linux/memory.h`, `bpf_jit.h`.
• Detected declarations: `function prepare_bpf_tail_call_cnt`, `function build_prologue`, `function __build_epilogue`, `function build_epilogue`, `function bpf_jit_supports_kfunc_call`, `function bpf_jit_supports_far_kfunc_call`, `function emit_bpf_tail_call`, `function emit_store_stack_imm64`, `function emit_atomic_rmw`, `function emit_atomic_ld_st`.
• Atlas domain: Architecture Layer / arch/loongarch.
• Implementation status: source implementation candidate.
• This snippet crosses the user/kernel memory boundary; validate fault handling and access checks before translating the pattern.
• Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.