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authorIlya Leoshkevich <iii@linux.ibm.com>2019-11-15 13:37:22 +0100
committerDaniel Borkmann <daniel@iogearbox.net>2019-11-15 22:25:00 +0100
commitb7b3fc8dd95bc02bd30680da258e09dda55270db (patch)
treef495c80bad776b25b2734b3257f6906de6b9365d /kernel
parente47a179997ceee6864fbae620eee09ea9c345a4d (diff)
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')
-rw-r--r--kernel/bpf/core.c4
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.