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bpf: Allow to resolve bpf trampoline and dispatcher in unwind

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When unwinding the stack we need to identify each address
to successfully continue. Adding latch tree to keep trampolines
for quick lookup during the unwind.

The patch uses first 48 bytes for latch tree node, leaving 4048
bytes from the rest of the page for trampoline or dispatcher
generated code.

It's still enough not to affect trampoline and dispatcher progs
maximum counts.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200123161508.915203-3-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2020-01-23 17:15:07 +01:00 • committed by Alexei Starovoitov
parent 84ad7a7ab6
commit e9b4e606c2
4 changed files with 90 additions and 13 deletions
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12
include/linux/bpf.h
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@ -525,7 +525,6 @@ 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);
#define BPF_DISPATCHER_INIT(name) { \
.mutex = __MUTEX_INITIALIZER(name.mutex), \
.func = &name##func, \
@ -557,6 +556,13 @@ void *bpf_jit_alloc_exec_page(void);
#define BPF_DISPATCHER_PTR(name) (&name)
void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from,
struct bpf_prog *to);
struct bpf_image {
struct latch_tree_node tnode;
unsigned char data[];
};
#define BPF_IMAGE_SIZE (PAGE_SIZE - sizeof(struct bpf_image))
bool is_bpf_image_address(unsigned long address);
void *bpf_image_alloc(void);
#else
static inline struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
{
@ -578,6 +584,10 @@ static inline void bpf_trampoline_put(struct bpf_trampoline *tr) {}
static inline void bpf_dispatcher_change_prog(struct bpf_dispatcher *d,
struct bpf_prog *from,
struct bpf_prog *to) {}
static inline bool is_bpf_image_address(unsigned long address)
{
return false;
}
#endif
struct bpf_func_info_aux {