tools/testing/selftests/bpf/verifier/atomic_xor.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/bpf/verifier/atomic_xor.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/bpf/verifier/atomic_xor.c
Extension
.c
Size
2351 bytes
Lines
78
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

{
	"BPF_ATOMIC XOR without fetch",
	.insns = {
		/* val = 0x110; */
		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0x110),
		/* atomic_xor(&val, 0x011); */
		BPF_MOV64_IMM(BPF_REG_1, 0x011),
		BPF_ATOMIC_OP(BPF_DW, BPF_XOR, BPF_REG_10, BPF_REG_1, -8),
		/* if (val != 0x101) exit(2); */
		BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0x101, 2),
		BPF_MOV64_IMM(BPF_REG_0, 2),
		BPF_EXIT_INSN(),
		/* r1 should not be clobbered, no BPF_FETCH flag */
		BPF_MOV64_IMM(BPF_REG_0, 0),
		BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0x011, 1),
		BPF_MOV64_IMM(BPF_REG_0, 1),
		BPF_EXIT_INSN(),
	},
	.result = ACCEPT,
},
{
	"BPF_ATOMIC XOR with fetch",
	.insns = {
		BPF_MOV64_IMM(BPF_REG_0, 123),
		/* val = 0x110; */
		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0x110),
		/* old = atomic_fetch_xor(&val, 0x011); */
		BPF_MOV64_IMM(BPF_REG_1, 0x011),
		BPF_ATOMIC_OP(BPF_DW, BPF_XOR | BPF_FETCH, BPF_REG_10, BPF_REG_1, -8),
		/* if (old != 0x110) exit(3); */
		BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0x110, 2),
		BPF_MOV64_IMM(BPF_REG_0, 3),
		BPF_EXIT_INSN(),
		/* if (val != 0x101) exit(2); */
		BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_10, -8),
		BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0x101, 2),
		BPF_MOV64_IMM(BPF_REG_1, 2),
		BPF_EXIT_INSN(),
		/* Check R0 wasn't clobbered (fxor fear of x86 JIT bug) */
		BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 123, 2),
		BPF_MOV64_IMM(BPF_REG_0, 1),
		BPF_EXIT_INSN(),
		/* exit(0); */
		BPF_MOV64_IMM(BPF_REG_0, 0),
		BPF_EXIT_INSN(),
	},
	.result = ACCEPT,
},
{
	"BPF_ATOMIC XOR with fetch 32bit",
	.insns = {
		/* r0 = (s64) -1 */
		BPF_MOV64_IMM(BPF_REG_0, 0),
		BPF_ALU64_IMM(BPF_SUB, BPF_REG_0, 1),
		/* val = 0x110; */
		BPF_ST_MEM(BPF_W, BPF_REG_10, -4, 0x110),
		/* old = atomic_fetch_xor(&val, 0x011); */
		BPF_MOV32_IMM(BPF_REG_1, 0x011),
		BPF_ATOMIC_OP(BPF_W, BPF_XOR | BPF_FETCH, BPF_REG_10, BPF_REG_1, -4),
		/* if (old != 0x110) exit(3); */
		BPF_JMP32_IMM(BPF_JEQ, BPF_REG_1, 0x110, 2),
		BPF_MOV32_IMM(BPF_REG_0, 3),
		BPF_EXIT_INSN(),
		/* if (val != 0x101) exit(2); */
		BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, -4),
		BPF_JMP32_IMM(BPF_JEQ, BPF_REG_1, 0x101, 2),
		BPF_MOV32_IMM(BPF_REG_1, 2),
		BPF_EXIT_INSN(),
		/* Check R0 wasn't clobbered (fxor fear of x86 JIT bug)
		 * It should be -1 so add 1 to get exit code.
		 */
		BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 1),
		BPF_EXIT_INSN(),
	},
	.result = ACCEPT,
},

Annotation

Implementation Notes