[PATCH v2 17/20] bpf: Use vmalloc special flag

Rick Edgecombe
2019-01-29T00:39:56Z

Use new flag VM_HAS_SPECIAL_PERMS for handling freeing of special
permissioned memory in vmalloc and remove places where memory was set RW
before freeing which is no longer needed. Also we no longer need a bit to
track if the memory is RO because it is tracked in vmalloc.

Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
include/linux/filter.h | 16 +++-------------
kernel/bpf/core.c | 1 -
2 files changed, 3 insertions(+), 14 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 9cdfab7f383c..cc9581dd9c58 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -20,6 +20,7 @@
#include <linux/set_memory.h>
#include <linux/kallsyms.h>
#include <linux/if_vlan.h>
+#include <linux/vmalloc.h>

#include <net/sch_generic.h>

@@ -483,7 +484,6 @@ struct bpf_prog {
u16 pages; /* Number of allocated pages */
u16 jited:1, /* Is our filter JIT'ed? */
jit_requested:1,/* archs need to JIT the prog */
- undo_set_mem:1, /* Passed set_memory_ro() checkpoint */
gpl_compatible:1, /* Is filter GPL compatible? */
cb_access:1, /* Is control block accessed? */
dst_needed:1, /* Do we need dst entry? */
@@ -681,26 +681,17 @@ bpf_ctx_narrow_access_ok(u32 off, u32 size, u32 size_default)

static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
{
+ set_vm_special(fp);
set_memory_ro((unsigned long)fp, fp->pages);
}

-static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
-{
- if (fp->undo_set_mem)
- set_memory_rw((unsigned long)fp, fp->pages);
-}
-
static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)
{
+ set_vm_special(hdr);
set_memory_ro((unsigned long)hdr, hdr->pages);
set_memory_x((unsigned long)hdr, hdr->pages);
}

-static inline void bpf_jit_binary_unlock_ro(struct bpf_binary_header *hdr)
-{
- set_memory_rw((unsigned long)hdr, hdr->pages);
-}
-
static inline struct bpf_binary_header *
bpf_jit_binary_hdr(const struct bpf_prog *fp)
{
@@ -735,7 +726,6 @@ void __bpf_prog_free(struct bpf_prog *fp);

static inline void bpf_prog_unlock_free(struct bpf_prog *fp)
{
- bpf_prog_unlock_ro(fp);
__bpf_prog_free(fp);
}

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 19c49313c709..465c1c3623e8 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -804,7 +804,6 @@ void __weak bpf_jit_free(struct bpf_prog *fp)
if (fp->jited) {
struct bpf_binary_header *hdr = bpf_jit_binary_hdr(fp);

- bpf_jit_binary_unlock_ro(hdr);
bpf_jit_binary_free(hdr);

WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp));
--
2.17.1