forked from OSchip/llvm-project
56db145164
If the offset cannot fit into the instruction, an addition to the
pointer is emitted before the actual access. However, BPF offsets are
16-bit but LLVM considers them to be, for the matter of this check,
to be 32-bit long.
This causes the following program:
int bpf_prog1(void *ign)
{
volatile unsigned long t = 0x8983984739ull;
return *(unsigned long *)((0xffffffff8fff0002ull) + t);
}
To generate the following (wrong) code:
0: 18 01 00 00 39 47 98 83 00 00 00 00 89 00 00 00
r1 = 590618314553ll
2: 7b 1a f8 ff 00 00 00 00 *(u64 *)(r10 - 8) = r1
3: 79 a1 f8 ff 00 00 00 00 r1 = *(u64 *)(r10 - 8)
4: 79 10 02 00 00 00 00 00 r0 = *(u64 *)(r1 + 2)
5: 95 00 00 00 00 00 00 00 exit
Fix it by changing the offset check to 16-bit.
Patch by Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Differential Revision: https://reviews.llvm.org/D32055
llvm-svn: 300269
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| .. | ||
| alu8.ll | ||
| atomics.ll | ||
| basictest.ll | ||
| byval.ll | ||
| cc_args.ll | ||
| cc_args_be.ll | ||
| cc_ret.ll | ||
| cmp.ll | ||
| dwarfdump.ll | ||
| ex1.ll | ||
| fi_ri.ll | ||
| intrinsics.ll | ||
| lit.local.cfg | ||
| load.ll | ||
| loops.ll | ||
| many_args1.ll | ||
| many_args2.ll | ||
| mem_offset.ll | ||
| objdump_atomics.ll | ||
| objdump_intrinsics.ll | ||
| objdump_trivial.ll | ||
| sanity.ll | ||
| sdiv_error.ll | ||
| setcc.ll | ||
| shifts.ll | ||
| sockex2.ll | ||
| struct_ret1.ll | ||
| struct_ret2.ll | ||
| undef.ll | ||
| vararg1.ll | ||
| warn-call.ll | ||
| warn-stack.ll | ||