diff options
| author | Ilya Leoshkevich <iii@linux.ibm.com> | 2019-11-15 15:37:22 +0300 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-11-16 00:25:00 +0300 |
| commit | b7b3fc8dd95bc02bd30680da258e09dda55270db (patch) | |
| tree | f495c80bad776b25b2734b3257f6906de6b9365d /kernel/bpf | |
| parent | e47a179997ceee6864fbae620eee09ea9c345a4d (diff) | |
| download | linux-b7b3fc8dd95bc02bd30680da258e09dda55270db.tar.xz | |
bpf: Support doubleword alignment in bpf_jit_binary_alloc
Currently passing alignment greater than 4 to bpf_jit_binary_alloc does
not work: in such cases it silently aligns only to 4 bytes.
On s390, in order to load a constant from memory in a large (>512k) BPF
program, one must use lgrl instruction, whose memory operand must be
aligned on an 8-byte boundary.
This patch makes it possible to request 8-byte alignment from
bpf_jit_binary_alloc, and also makes it issue a warning when an
unsupported alignment is requested.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191115123722.58462-1-iii@linux.ibm.com
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/core.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index c1fde0303280..99693f3c4e99 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -31,6 +31,7 @@ #include <linux/rcupdate.h> #include <linux/perf_event.h> #include <linux/extable.h> +#include <linux/log2.h> #include <asm/unaligned.h> /* Registers */ @@ -815,6 +816,9 @@ bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, struct bpf_binary_header *hdr; u32 size, hole, start, pages; + WARN_ON_ONCE(!is_power_of_2(alignment) || + alignment > BPF_IMAGE_ALIGNMENT); + /* Most of BPF filters are really small, but if some of them * fill a page, allow at least 128 extra bytes to insert a * random section of illegal instructions. |