[PATCH bpf-next 2/8] bpf: Let bpf_prog_pack_free handle any pointer

Song Liu
2023-09-20T05:32:22Z

Currently, bpf_prog_pack_free only can only free pointer to struct
bpf_binary_header, which is not flexible. Add a size argument to
bpf_prog_pack_free so that it can handle any pointer.

Signed-off-by: Song Liu <song@kernel.org>
---
include/linux/filter.h | 2 +-
kernel/bpf/core.c | 21 ++++++++++-----------
kernel/bpf/dispatcher.c | 5 +----
3 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 27406aee2d40..eda9efe20026 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1073,7 +1073,7 @@ struct bpf_binary_header *
bpf_jit_binary_pack_hdr(const struct bpf_prog *fp);

void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns);
-void bpf_prog_pack_free(struct bpf_binary_header *hdr);
+void bpf_prog_pack_free(void *ptr, u32 size);

static inline bool bpf_prog_kallsyms_verify_off(const struct bpf_prog *fp)
{
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 08626b519ce2..fcdf710e6a32 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -928,20 +928,20 @@ void *bpf_prog_pack_alloc(u32 size, bpf_jit_fill_hole_t bpf_fill_ill_insns)
return ptr;
}

-void bpf_prog_pack_free(struct bpf_binary_header *hdr)
+void bpf_prog_pack_free(void *ptr, u32 size)
{
struct bpf_prog_pack *pack = NULL, *tmp;
unsigned int nbits;
unsigned long pos;

mutex_lock(&pack_mutex);
- if (hdr->size > BPF_PROG_PACK_SIZE) {
- bpf_jit_free_exec(hdr);
+ if (size > BPF_PROG_PACK_SIZE) {
+ bpf_jit_free_exec(ptr);
goto out;
}

list_for_each_entry(tmp, &pack_list, list) {
- if ((void *)hdr >= tmp->ptr && (tmp->ptr + BPF_PROG_PACK_SIZE) > (void *)hdr) {
+ if (ptr >= tmp->ptr && (tmp->ptr + BPF_PROG_PACK_SIZE) > ptr) {
pack = tmp;
break;
}
@@ -950,10 +950,10 @@ void bpf_prog_pack_free(struct bpf_binary_header *hdr)
if (WARN_ONCE(!pack, "bpf_prog_pack bug\n"))
goto out;

- nbits = BPF_PROG_SIZE_TO_NBITS(hdr->size);
- pos = ((unsigned long)hdr - (unsigned long)pack->ptr) >> BPF_PROG_CHUNK_SHIFT;
+ nbits = BPF_PROG_SIZE_TO_NBITS(size);
+ pos = ((unsigned long)ptr - (unsigned long)pack->ptr) >> BPF_PROG_CHUNK_SHIFT;

- WARN_ONCE(bpf_arch_text_invalidate(hdr, hdr->size),
+ WARN_ONCE(bpf_arch_text_invalidate(ptr, size),
"bpf_prog_pack bug: missing bpf_arch_text_invalidate?\n");

bitmap_clear(pack->bitmap, pos, nbits);
@@ -1100,8 +1100,7 @@ bpf_jit_binary_pack_alloc(unsigned int proglen, u8 **image_ptr,

*rw_header = kvmalloc(size, GFP_KERNEL);
if (!*rw_header) {
- bpf_arch_text_copy(&ro_header->size, &size, sizeof(size));
- bpf_prog_pack_free(ro_header);
+ bpf_prog_pack_free(ro_header, size);
bpf_jit_uncharge_modmem(size);
return NULL;
}
@@ -1132,7 +1131,7 @@ int bpf_jit_binary_pack_finalize(struct bpf_prog *prog,
kvfree(rw_header);

if (IS_ERR(ptr)) {
- bpf_prog_pack_free(ro_header);
+ bpf_prog_pack_free(ro_header, ro_header->size);
return PTR_ERR(ptr);
}
return 0;
@@ -1153,7 +1152,7 @@ void bpf_jit_binary_pack_free(struct bpf_binary_header *ro_header,
{
u32 size = ro_header->size;

- bpf_prog_pack_free(ro_header);
+ bpf_prog_pack_free(ro_header, size);
kvfree(rw_header);
bpf_jit_uncharge_modmem(size);
}
diff --git a/kernel/bpf/dispatcher.c b/kernel/bpf/dispatcher.c
index fa3e9225aedc..56760fc10e78 100644
--- a/kernel/bpf/dispatcher.c
+++ b/kernel/bpf/dispatcher.c
@@ -150,10 +150,7 @@ void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from,
goto out;
d->rw_image = bpf_jit_alloc_exec(PAGE_SIZE);
if (!d->rw_image) {
- u32 size = PAGE_SIZE;
-
- bpf_arch_text_copy(d->image, &size, sizeof(size));
- bpf_prog_pack_free((struct bpf_binary_header *)d->image);
+ bpf_prog_pack_free(d->image, PAGE_SIZE);
d->image = NULL;
goto out;
}
--
2.34.1