shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-06 10:58:48 +09:00
Code Issues Packages Projects Releases Wiki Activity

Revert "UPSTREAM: bpf: Introduce BPF dispatcher"

Browse Source 
This reverts commit 22cf3ea720.

It conflicts with the BPF merge and will come in through the upstream
tree.

Cc: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I404d2e9efcd6057d481be2562cb9b2a559b70e58
This commit is contained in:
Greg Kroah-Hartman
2020-01-31 08:14:27 +01:00
parent 4f91256854
commit d12d53b72f
4 changed files with 0 additions and 337 deletions
Download Patch File Download Diff File Expand all files Collapse all files

122
arch/x86/net/bpf_jit_comp.c
View File

@@ -10,12 +10,10 @@
#include <linux/if_vlan.h>
#include <linux/bpf.h>
#include <linux/memory.h>
#include <linux/sort.h>
#include <asm/extable.h>
#include <asm/set_memory.h>
#include <asm/nospec-branch.h>
#include <asm/text-patching.h>
#include <asm/asm-prototypes.h>
static u8 *emit_code(u8 *ptr, u32 bytes, unsigned int len)
{
@@ -1532,126 +1530,6 @@ int arch_prepare_bpf_trampoline(void *image, struct btf_func_model *m, u32 flags
return 0;
}
static int emit_cond_near_jump(u8 **pprog, void *func, void *ip, u8 jmp_cond)
{
u8 *prog = *pprog;
int cnt = 0;
s64 offset;
offset = func - (ip + 2 + 4);
if (!is_simm32(offset)) {
pr_err("Target %p is out of range\n", func);
return -EINVAL;
}
EMIT2_off32(0x0F, jmp_cond + 0x10, offset);
*pprog = prog;
return 0;
}
static int emit_fallback_jump(u8 **pprog)
{
u8 *prog = *pprog;
int err = 0;
#ifdef CONFIG_RETPOLINE
/* Note that this assumes the the compiler uses external
* thunks for indirect calls. Both clang and GCC use the same
* naming convention for external thunks.
*/
err = emit_jump(&prog, __x86_indirect_thunk_rdx, prog);
#else
int cnt = 0;
EMIT2(0xFF, 0xE2); /* jmp rdx */
#endif
*pprog = prog;
return err;
}
static int emit_bpf_dispatcher(u8 **pprog, int a, int b, s64 *progs)
{
int pivot, err, jg_bytes = 1, cnt = 0;
u8 *jg_reloc, *prog = *pprog;
s64 jg_offset;
if (a == b) {
/* Leaf node of recursion, i.e. not a range of indices
* anymore.
*/
EMIT1(add_1mod(0x48, BPF_REG_3)); /* cmp rdx,func */
if (!is_simm32(progs[a]))
return -1;
EMIT2_off32(0x81, add_1reg(0xF8, BPF_REG_3),
progs[a]);
err = emit_cond_near_jump(&prog, /* je func */
(void *)progs[a], prog,
X86_JE);
if (err)
return err;
err = emit_fallback_jump(&prog); /* jmp thunk/indirect */
if (err)
return err;
*pprog = prog;
return 0;
}
/* Not a leaf node, so we pivot, and recursively descend into
* the lower and upper ranges.
*/
pivot = (b - a) / 2;
EMIT1(add_1mod(0x48, BPF_REG_3)); /* cmp rdx,func */
if (!is_simm32(progs[a + pivot]))
return -1;
EMIT2_off32(0x81, add_1reg(0xF8, BPF_REG_3), progs[a + pivot]);
if (pivot > 2) { /* jg upper_part */
/* Require near jump. */
jg_bytes = 4;
EMIT2_off32(0x0F, X86_JG + 0x10, 0);
} else {
EMIT2(X86_JG, 0);
}
jg_reloc = prog;
err = emit_bpf_dispatcher(&prog, a, a + pivot, /* emit lower_part */
progs);
if (err)
return err;
jg_offset = prog - jg_reloc;
emit_code(jg_reloc - jg_bytes, jg_offset, jg_bytes);
err = emit_bpf_dispatcher(&prog, a + pivot + 1, /* emit upper_part */
b, progs);
if (err)
return err;
*pprog = prog;
return 0;
}
static int cmp_ips(const void *a, const void *b)
{
const s64 *ipa = a;
const s64 *ipb = b;
if (*ipa > *ipb)
return 1;
if (*ipa < *ipb)
return -1;
return 0;
}
int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs)
{
u8 *prog = image;
sort(funcs, num_funcs, sizeof(funcs[0]), cmp_ips, NULL);
return emit_bpf_dispatcher(&prog, 0, num_funcs - 1, funcs);
}
struct x64_jit_data {
struct bpf_binary_header *header;
int *addrs;

56
include/linux/bpf.h
View File

@@ -471,61 +471,12 @@ struct bpf_trampoline {
void *image;
u64 selector;
};
#define BPF_DISPATCHER_MAX 64 /* Fits in 2048B */
struct bpf_dispatcher_prog {
struct bpf_prog *prog;
refcount_t users;
};
struct bpf_dispatcher {
/* dispatcher mutex */
struct mutex mutex;
void *func;
struct bpf_dispatcher_prog progs[BPF_DISPATCHER_MAX];
int num_progs;
void *image;
u32 image_off;
};
#ifdef CONFIG_BPF_JIT
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, \
.progs = {}, \
.num_progs = 0, \
.image = NULL, \
.image_off = 0 \
}
#define DEFINE_BPF_DISPATCHER(name) \
noinline unsigned int name##func( \
const void *ctx, \
const struct bpf_insn *insnsi, \
unsigned int (*bpf_func)(const void *, \
const struct bpf_insn *)) \
{ \
return bpf_func(ctx, insnsi); \
} \
EXPORT_SYMBOL(name##func); \
struct bpf_dispatcher name = BPF_DISPATCHER_INIT(name);
#define DECLARE_BPF_DISPATCHER(name) \
unsigned int name##func( \
const void *ctx, \
const struct bpf_insn *insnsi, \
unsigned int (*bpf_func)(const void *, \
const struct bpf_insn *)); \
extern struct bpf_dispatcher name;
#define BPF_DISPATCHER_FUNC(name) name##func
#define BPF_DISPATCHER_PTR(name) (&name)
void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from,
struct bpf_prog *to);
#else
static inline struct bpf_trampoline *bpf_trampoline_lookup(u64 key)
{
@@ -540,13 +491,6 @@ static inline int bpf_trampoline_unlink_prog(struct bpf_prog *prog)
return -ENOTSUPP;
}
static inline void bpf_trampoline_put(struct bpf_trampoline *tr) {}
#define DEFINE_BPF_DISPATCHER(name)
#define DECLARE_BPF_DISPATCHER(name)
#define BPF_DISPATCHER_FUNC(name) bpf_dispatcher_nopfunc
#define BPF_DISPATCHER_PTR(name) NULL
static inline void bpf_dispatcher_change_prog(struct bpf_dispatcher *d,
struct bpf_prog *from,
struct bpf_prog *to) {}
#endif
struct bpf_func_info_aux {

1
kernel/bpf/Makefile
View File

@@ -8,7 +8,6 @@ obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o
obj-$(CONFIG_BPF_SYSCALL) += disasm.o
obj-$(CONFIG_BPF_JIT) += trampoline.o
obj-$(CONFIG_BPF_SYSCALL) += btf.o
obj-$(CONFIG_BPF_JIT) += dispatcher.o
ifeq ($(CONFIG_NET),y)
obj-$(CONFIG_BPF_SYSCALL) += devmap.o
obj-$(CONFIG_BPF_SYSCALL) += cpumap.o

158
kernel/bpf/dispatcher.c
View File

@@ -1,158 +0,0 @@
// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2019 Intel Corporation. */
#include <linux/hash.h>
#include <linux/bpf.h>
#include <linux/filter.h>
/* The BPF dispatcher is a multiway branch code generator. The
* dispatcher is a mechanism to avoid the performance penalty of an
* indirect call, which is expensive when retpolines are enabled. A
* dispatch client registers a BPF program into the dispatcher, and if
* there is available room in the dispatcher a direct call to the BPF
* program will be generated. All calls to the BPF programs called via
* the dispatcher will then be a direct call, instead of an
* indirect. The dispatcher hijacks a trampoline function it via the
* __fentry__ of the trampoline. The trampoline function has the
* following signature:
*
* unsigned int trampoline(const void *ctx, const struct bpf_insn *insnsi,
* unsigned int (*bpf_func)(const void *,
* const struct bpf_insn *));
*/
static struct bpf_dispatcher_prog *bpf_dispatcher_find_prog(
struct bpf_dispatcher *d, struct bpf_prog *prog)
{
int i;
for (i = 0; i < BPF_DISPATCHER_MAX; i++) {
if (prog == d->progs[i].prog)
return &d->progs[i];
}
return NULL;
}
static struct bpf_dispatcher_prog *bpf_dispatcher_find_free(
struct bpf_dispatcher *d)
{
return bpf_dispatcher_find_prog(d, NULL);
}
static bool bpf_dispatcher_add_prog(struct bpf_dispatcher *d,
struct bpf_prog *prog)
{
struct bpf_dispatcher_prog *entry;
if (!prog)
return false;
entry = bpf_dispatcher_find_prog(d, prog);
if (entry) {
refcount_inc(&entry->users);
return false;
}
entry = bpf_dispatcher_find_free(d);
if (!entry)
return false;
bpf_prog_inc(prog);
entry->prog = prog;
refcount_set(&entry->users, 1);
d->num_progs++;
return true;
}
static bool bpf_dispatcher_remove_prog(struct bpf_dispatcher *d,
struct bpf_prog *prog)
{
struct bpf_dispatcher_prog *entry;
if (!prog)
return false;
entry = bpf_dispatcher_find_prog(d, prog);
if (!entry)
return false;
if (refcount_dec_and_test(&entry->users)) {
entry->prog = NULL;
bpf_prog_put(prog);
d->num_progs--;
return true;
}
return false;
}
int __weak arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs)
{
return -ENOTSUPP;
}
static int bpf_dispatcher_prepare(struct bpf_dispatcher *d, void *image)
{
s64 ips[BPF_DISPATCHER_MAX] = {}, *ipsp = &ips[0];
int i;
for (i = 0; i < BPF_DISPATCHER_MAX; i++) {
if (d->progs[i].prog)
*ipsp++ = (s64)(uintptr_t)d->progs[i].prog->bpf_func;
}
return arch_prepare_bpf_dispatcher(image, &ips[0], d->num_progs);
}
static void bpf_dispatcher_update(struct bpf_dispatcher *d, int prev_num_progs)
{
void *old, *new;
u32 noff;
int err;
if (!prev_num_progs) {
old = NULL;
noff = 0;
} else {
old = d->image + d->image_off;
noff = d->image_off ^ (PAGE_SIZE / 2);
}
new = d->num_progs ? d->image + noff : NULL;
if (new) {
if (bpf_dispatcher_prepare(d, new))
return;
}
err = bpf_arch_text_poke(d->func, BPF_MOD_JUMP, old, new);
if (err || !new)
return;
d->image_off = noff;
}
void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from,
struct bpf_prog *to)
{
bool changed = false;
int prev_num_progs;
if (from == to)
return;
mutex_lock(&d->mutex);
if (!d->image) {
d->image = bpf_jit_alloc_exec_page();
if (!d->image)
goto out;
}
prev_num_progs = d->num_progs;
changed |= bpf_dispatcher_remove_prog(d, from);
changed |= bpf_dispatcher_add_prog(d, to);
if (!changed)
goto out;
bpf_dispatcher_update(d, prev_num_progs);
out:
mutex_unlock(&d->mutex);
}