Add APF opcodes to read/write data memory (take 2)

The new opcodes are LDDW (LoaD Data Word) and STDW (STore Data Word)

The only supported addressing mode is register-indirect with immediate
offset (register value + immediate value). Since there's a single
register bit encoded in the opcode, the other register is implicitly
used for the address operand. Hence, the following variations are
possible:

  lddw R0, [1234]R1  ; R0 = *(R1 + 1234)
  lddw R1, [1234]R0  ; R1 = *(R0 + 1234)
  stdw R0, [1234]R1  ; *(R1 + 1234) = R0
  stdw R1, [1234]R0  ; *(R0 + 1234) = R1

The immediate can also be specified to be length 0, making the memory
access equivalent to a plain register-indirect with no offset.

  lddw R0, R1  ; R0 = *R1
  lddw R1, R0  ; R1 = *R0
  stdw R0, R1  ; *R1 = R0
  stdw R1, R0  ; *R0 = R1

The encoding of the above instructions is a single byte, making a
typical counter increment more efficient, especially when the address
requires a multi-byte immediate:

  ldh   R1, 1234    ; address of our packet counter (3 bytes)
  lddw  R0, R1      ; load the counter from address 1234 (1 byte)
  add   R0, 1       ; increment the counter (2 bytes)
  stdw  R0, R1      ; write-back to data ram (1 byte)

Total: 7 bytes. Defining a separate INCW instruction would reduce the
above sequence down to 3 bytes (or 4 bytes if using an EXT opcode to
avoid wasting opcodes). This optimization can be added at a later point
if the data access patterns of production APF code justify it.

Bug: 73804303
Test: runtest -x tests/net/java/android/net/apf/ApfTest.java
Change-Id: Ibbd427e12987a1eef63b41d816af05a1bd9f9170

1 files changed, 21 insertions, 6 deletions

diff --git a/apf_run.c b/apf_run.c
index 32b4506..dab7f5e 100644
--- a/apf_run.c
+++ b/apf_run.c
@@ -50,13 +50,20 @@ int parse_hex(char* input, uint8_t** output) {
     return length;
 }
 
+void print_hex(uint8_t* input, int len) {
+    for (int i = 0; i < len; ++i) {
+        printf("%02x", input[i]);
+    }
+}
+
 int main(int argc, char* argv[]) {
-    if (argc != 4) {
+    if (argc < 3 || argc > 5) {
         fprintf(stderr,
-                "Usage: %s <program> <packet> <program age>\n"
+                "Usage: %s <program> <packet> [<data>] [<age>]\n"
                 "  program:     APF program, in hex\n"
                 "  packet:      Packet to run through program, in hex\n"
-                "  program age: Age of program in seconds.\n",
+                "  data:        Data memory contents, in hex\n",
+                "  age:         Age of program in seconds (default: 0)\n",
                 basename(argv[0]));
         exit(1);
     }
@@ -64,11 +71,19 @@ int main(int argc, char* argv[]) {
     uint32_t program_len = parse_hex(argv[1], &program);
     uint8_t* packet;
     uint32_t packet_len = parse_hex(argv[2], &packet);
-    uint32_t filter_age = atoi(argv[3]);
+    uint8_t* data = NULL;
+    uint32_t data_len = argc > 3 ? parse_hex(argv[3], &data) : 0;
+    uint32_t filter_age = argc > 4 ? atoi(argv[4]) : 0;
     int ret = accept_packet(program, program_len, packet, packet_len,
-                            filter_age);
+                            data, data_len, filter_age);
     printf("Packet %sed\n", ret ? "pass" : "dropp");
+    if (data) {
+        printf("Data: ");
+        print_hex(data, data_len);
+        printf("\n");
+        free(data);
+    }
     free(program);
     free(packet);
     return ret;
-}
\ No newline at end of file
+}