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authorDavid Daney <david.daney@cavium.com>2017-06-13 16:49:36 -0700
committerDavid S. Miller <davem@davemloft.net>2017-06-14 15:03:22 -0400
commitb7127cfea050a3b371d6da7a3ce9e69942f945f0 (patch)
treeeaeff2121d53c4cafcb35c2227e9ee34ae6f9301 /lib
parente274da1a50f6f3c8216e5bb22e1b0964ab993f13 (diff)
test_bpf: Add test to make conditional jump cross a large number of insns.
On MIPS, conditional branches can only span 32k instructions. To exceed this limit in the JIT with the BPF maximum of 4k insns, we need to choose eBPF insns that expand to more than 8 machine instructions. Use BPF_LD_ABS as it is quite complex. This forces the JIT to invert the sense of the branch to branch around a long jump to the end. This (somewhat) verifies that the branch inversion logic and target address calculation of the long jumps are done correctly. Signed-off-by: David Daney <david.daney@cavium.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'lib')
-rw-r--r--lib/test_bpf.c32
1 files changed, 32 insertions, 0 deletions
diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index 070bde56474c..c871e0e76c2a 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -435,6 +435,30 @@ loop:
return 0;
}
+static int bpf_fill_jump_around_ld_abs(struct bpf_test *self)
+{
+ unsigned int len = BPF_MAXINSNS;
+ struct bpf_insn *insn;
+ int i = 0;
+
+ insn = kmalloc_array(len, sizeof(*insn), GFP_KERNEL);
+ if (!insn)
+ return -ENOMEM;
+
+ insn[i++] = BPF_MOV64_REG(R6, R1);
+ insn[i++] = BPF_LD_ABS(BPF_B, 0);
+ insn[i] = BPF_JMP_IMM(BPF_JEQ, R0, 10, len - i - 2);
+ i++;
+ while (i < len - 1)
+ insn[i++] = BPF_LD_ABS(BPF_B, 1);
+ insn[i] = BPF_EXIT_INSN();
+
+ self->u.ptr.insns = insn;
+ self->u.ptr.len = len;
+
+ return 0;
+}
+
static int __bpf_fill_stxdw(struct bpf_test *self, int size)
{
unsigned int len = BPF_MAXINSNS;
@@ -5044,6 +5068,14 @@ static struct bpf_test tests[] = {
{ { ETH_HLEN, 0xbef } },
.fill_helper = bpf_fill_ld_abs_vlan_push_pop,
},
+ {
+ "BPF_MAXINSNS: jump around ld_abs",
+ { },
+ INTERNAL,
+ { 10, 11 },
+ { { 2, 10 } },
+ .fill_helper = bpf_fill_jump_around_ld_abs,
+ },
/*
* LD_IND / LD_ABS on fragmented SKBs
*/