bpf/tests: Add test of LDX_MEM with operand aliasing

This patch adds a set of tests of BPF_LDX_MEM where both operand registers
are the same register. Mainly testing 32-bit JITs that may load a 64-bit
value in two 32-bit loads, and must not overwrite the address register.

Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211001130348.3670534-11-johan.almbladh@anyfinetworks.com

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index dfcbdff..b9fc330 100644 (file)
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -11133,6 +11133,64 @@ static struct bpf_test tests[] = {
                {},
                { { 0, 2 } },
        },
+       /* BPF_LDX_MEM with operand aliasing */
+       {
+               "LDX_MEM_B: operand register aliasing",
+               .u.insns_int = {
+                       BPF_ST_MEM(BPF_B, R10, -8, 123),
+                       BPF_MOV64_REG(R0, R10),
+                       BPF_LDX_MEM(BPF_B, R0, R0, -8),
+                       BPF_EXIT_INSN(),
+               },
+               INTERNAL,
+               { },
+               { { 0, 123 } },
+               .stack_depth = 8,
+       },
+       {
+               "LDX_MEM_H: operand register aliasing",
+               .u.insns_int = {
+                       BPF_ST_MEM(BPF_H, R10, -8, 12345),
+                       BPF_MOV64_REG(R0, R10),
+                       BPF_LDX_MEM(BPF_H, R0, R0, -8),
+                       BPF_EXIT_INSN(),
+               },
+               INTERNAL,
+               { },
+               { { 0, 12345 } },
+               .stack_depth = 8,
+       },
+       {
+               "LDX_MEM_W: operand register aliasing",
+               .u.insns_int = {
+                       BPF_ST_MEM(BPF_W, R10, -8, 123456789),
+                       BPF_MOV64_REG(R0, R10),
+                       BPF_LDX_MEM(BPF_W, R0, R0, -8),
+                       BPF_EXIT_INSN(),
+               },
+               INTERNAL,
+               { },
+               { { 0, 123456789 } },
+               .stack_depth = 8,
+       },
+       {
+               "LDX_MEM_DW: operand register aliasing",
+               .u.insns_int = {
+                       BPF_LD_IMM64(R1, 0x123456789abcdefULL),
+                       BPF_STX_MEM(BPF_DW, R10, R1, -8),
+                       BPF_MOV64_REG(R0, R10),
+                       BPF_LDX_MEM(BPF_DW, R0, R0, -8),
+                       BPF_ALU64_REG(BPF_SUB, R0, R1),
+                       BPF_MOV64_REG(R1, R0),
+                       BPF_ALU64_IMM(BPF_RSH, R1, 32),
+                       BPF_ALU64_REG(BPF_OR, R0, R1),
+                       BPF_EXIT_INSN(),
+               },
+               INTERNAL,
+               { },
+               { { 0, 0 } },
+               .stack_depth = 8,
+       },
        /*
         * Register (non-)clobbering tests for the case where a JIT implements
         * complex ALU or ATOMIC operations via function calls. If so, the