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bpf: Move trampoline JIT image allocation to a function

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Refactor the image allocation in the BPF trampoline code into a
separate function, so it can be shared with the BPF dispatcher in
upcoming commits.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191213175112.30208-2-bjorn.topel@gmail.com
This commit is contained in:
Björn Töpel 2019-12-13 18:51:07 +01:00 committed by Alexei Starovoitov
parent 91cbdf740a
commit 98e8627efc
2 changed files with 18 additions and 7 deletions
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1
include/linux/bpf.h
View File

@ -475,6 +475,7 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key);
int bpf_trampoline_link_prog(struct bpf_prog *prog);
int bpf_trampoline_unlink_prog(struct bpf_prog *prog);
void bpf_trampoline_put(struct bpf_trampoline *tr);
void *bpf_jit_alloc_exec_page(void);
#else
static inline struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
{

24
kernel/bpf/trampoline.c
View File

@ -13,6 +13,22 @@ static struct hlist_head trampoline_table[TRAMPOLINE_TABLE_SIZE];
/* serializes access to trampoline_table */
static DEFINE_MUTEX(trampoline_mutex);
void *bpf_jit_alloc_exec_page(void)
{
void *image;
image = bpf_jit_alloc_exec(PAGE_SIZE);
if (!image)
return NULL;
set_vm_flush_reset_perms(image);
/* Keep image as writeable. The alternative is to keep flipping ro/rw
* everytime new program is attached or detached.
*/
set_memory_x((long)image, 1);
return image;
}
struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
{
struct bpf_trampoline *tr;
@ -33,7 +49,7 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
goto out;
/* is_root was checked earlier. No need for bpf_jit_charge_modmem() */
image = bpf_jit_alloc_exec(PAGE_SIZE);
image = bpf_jit_alloc_exec_page();
if (!image) {
kfree(tr);
tr = NULL;
@ -47,12 +63,6 @@ struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
mutex_init(&tr->mutex);
for (i = 0; i < BPF_TRAMP_MAX; i++)
INIT_HLIST_HEAD(&tr->progs_hlist[i]);
set_vm_flush_reset_perms(image);
/* Keep image as writeable. The alternative is to keep flipping ro/rw
* everytime new program is attached or detached.
*/
set_memory_x((long)image, 1);
tr->image = image;
out:
mutex_unlock(&trampoline_mutex);