[PATCH v2 3/4] bpf: switch to new vmalloc vfree flags

Rick Edgecombe
2018-12-12T00:12:11Z

This switches to use the new vmalloc flags to control freeing memory with
special permissions.

Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
include/linux/filter.h | 26 ++++++++++++--------------
kernel/bpf/core.c | 1 -
2 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 795ff0b869bb..2aeb93d3337d 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>

@@ -487,7 +488,6 @@ 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? */
@@ -699,24 +699,23 @@ bpf_ctx_narrow_access_ok(u32 off, u32 size, u32 size_default)

static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
{
- fp->undo_set_mem = 1;
- set_memory_ro((unsigned long)fp, fp->pages);
-}
+ struct vm_struct *vm = find_vm_area(fp);

-static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
-{
- if (fp->undo_set_mem)
- set_memory_rw((unsigned long)fp, fp->pages);
+ if (vm)
+ vm->flags |= VM_HAS_SPECIAL_PERMS;
+ set_memory_ro((unsigned long)fp, fp->pages);
}

static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)
{
- set_memory_ro((unsigned long)hdr, hdr->pages);
-}
+ struct vm_struct *vm = find_vm_area(hdr);

-static inline void bpf_jit_binary_unlock_ro(struct bpf_binary_header *hdr)
-{
- set_memory_rw((unsigned long)hdr, hdr->pages);
+ if (vm) {
+ vm->flags |= VM_HAS_SPECIAL_PERMS;
+ vm->flags |= VM_IMMEDIATE_UNMAP;
+ }
+
+ set_memory_ro((unsigned long)hdr, hdr->pages);
}

static inline struct bpf_binary_header *
@@ -746,7 +745,6 @@ 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 b1a3545d0ec8..bd3efd7ce526 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -663,7 +663,6 @@ 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