sim/testsuite/sim/bpf/ldabs.s

   1 # mach: bpf
   2 # sim: --skb-data-offset=0x20
   3 # output: pass\nexit 0 (0x0)\n
   4 ;;; ldabs.s
   5 ;;; Tests for non-generic BPF load instructions in simulator.
   6 ;;; These instructions (ld{abs,ind}{b,h,w,dw}) are used to access
   7 ;;; kernel socket data from BPF programs for high performance filters.
   8 ;;;
   9 ;;; Register r6 is an implicit input holding a pointer to a struct sk_buff.
  10 ;;; Register r0 is an implicit output, holding the fetched data.
  11 ;;;
  12 ;;; e.g.
  13 ;;; ldabsw means:
  14 ;;; r0 = ntohl (*(u32 *) (((struct sk_buff *)r6)->data + imm32))
  15 ;;;
  16 ;;; ldindw means
  17 ;;; r0 = ntohl (*(u32 *) (((struct sk_buff *)r6)->data + src_reg + imm32))
  18
  19     .include "testutils.inc"
  20
  21     .text
  22     .global main
  23     .type main, @function
  24 main:
  25     ;; R6 holds a pointer to a struct sk_buff, which we pretend
  26     ;; exists at 0x1000
  27     mov         %r6, 0x1000
  28
  29     ;; We configure skb-data-offset=0x20
  30     ;; This specifies offsetof(struct sk_buff, data), where the field 'data'
  31     ;; is a pointer a data buffer, in this case at 0x2000
  32     stw         [%r6+0x20], 0x2000
  33
  34     ;; Write the value 0x7eadbeef into memory at 0x2004
  35     ;; i.e. offset 4 within the data buffer pointed to by
  36     ;; ((struct sk_buff *)r6)->data
  37     stw         [%r6+0x1004], 0xdeadbeef
  38
  39     ;; Now load data[4] into r0 using the ldabsw instruction
  40     ldabsw      0x4
  41
  42     ;; ...and compare to what we expect
  43     fail_ne32   %r0, 0xdeadbeef
  44
  45     ;; Repeat for a half-word (2-bytes)
  46     sth         [%r6+0x1008], 0x1234
  47     ldabsh      0x8
  48     fail_ne32   %r0, 0x1234
  49
  50     ;; Repeat for a single byte
  51     stb         [%r6+0x1010], 0x5a
  52     ldabsb      0x10
  53     fail_ne32   %r0, 0x5a
  54
  55     ;; Repeat for a double-word (8-byte)
  56     ;; (note: fail_ne macro uses r0, so copy to another r1 to compare)
  57     lddw        %r2, 0x1234deadbeef5678
  58     stxdw       [%r6+0x1018], %r2
  59     ldabsdw     0x18
  60     mov         %r1, %r0
  61     fail_ne     %r1, 0x1234deadbeef5678
  62
  63     ;; Now, we do the same for the indirect loads
  64     mov         %r7, 0x100
  65     stw         [%r6+0x1100], 0xfeedbeef
  66
  67     ldindw      %r7, 0x0
  68     fail_ne32   %r0, 0xfeedbeef
  69
  70     ;; half-word
  71     sth         [%r6+0x1104], 0x6789
  72     ldindh      %r7, 0x4
  73     fail_ne32   %r0, 0x6789
  74
  75     ;; byte
  76     stb         [%r6+0x1108], 0x5f
  77     ldindb      %r7, 0x8
  78     fail_ne32   %r0, 0x5f
  79
  80     ;; double-word
  81     lddw        %r2, 0xcafe12345678d00d
  82     stxdw       [%r6+0x1110], %r2
  83     ldinddw     %r7, 0x10
  84     mov         %r1, %r0
  85     fail_ne     %r1, 0xcafe12345678d00d
  86
  87     pass