#include "bpf_gen_internal.h"
#include "skel_internal.h"
-#define MAX_USED_MAPS 64
-#define MAX_USED_PROGS 32
+#define MAX_USED_MAPS 64
+#define MAX_USED_PROGS 32
+#define MAX_KFUNC_DESCS 256
+#define MAX_FD_ARRAY_SZ (MAX_USED_PROGS + MAX_KFUNC_DESCS)
/* The following structure describes the stack layout of the loader program.
* In addition R6 contains the pointer to context.
*/
struct loader_stack {
__u32 btf_fd;
- __u32 map_fd[MAX_USED_MAPS];
__u32 prog_fd[MAX_USED_PROGS];
__u32 inner_map_fd;
};
if (realloc_data_buf(gen, size8))
return 0;
prev = gen->data_cur;
- memcpy(gen->data_cur, data, size);
- gen->data_cur += size;
- memcpy(gen->data_cur, &zero, size8 - size);
- gen->data_cur += size8 - size;
+ if (data) {
+ memcpy(gen->data_cur, data, size);
+ memcpy(gen->data_cur + size, &zero, size8 - size);
+ } else {
+ memset(gen->data_cur, 0, size8);
+ }
+ gen->data_cur += size8;
return prev - gen->data_start;
}
+/* Get index for map_fd/btf_fd slot in reserved fd_array, or in data relative
+ * to start of fd_array. Caller can decide if it is usable or not.
+ */
+static int add_map_fd(struct bpf_gen *gen)
+{
+ if (!gen->fd_array)
+ gen->fd_array = add_data(gen, NULL, MAX_FD_ARRAY_SZ * sizeof(int));
+ if (gen->nr_maps == MAX_USED_MAPS) {
+ pr_warn("Total maps exceeds %d\n", MAX_USED_MAPS);
+ gen->error = -E2BIG;
+ return 0;
+ }
+ return gen->nr_maps++;
+}
+
+static int add_kfunc_btf_fd(struct bpf_gen *gen)
+{
+ int cur;
+
+ if (!gen->fd_array)
+ gen->fd_array = add_data(gen, NULL, MAX_FD_ARRAY_SZ * sizeof(int));
+ if (gen->nr_fd_array == MAX_KFUNC_DESCS) {
+ cur = add_data(gen, NULL, sizeof(int));
+ return (cur - gen->fd_array) / sizeof(int);
+ }
+ return MAX_USED_MAPS + gen->nr_fd_array++;
+}
+
+static int blob_fd_array_off(struct bpf_gen *gen, int index)
+{
+ return gen->fd_array + index * sizeof(int);
+}
+
static int insn_bytes_to_bpf_size(__u32 sz)
{
switch (sz) {
emit(gen, BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, 0));
}
-/* *(u64 *)(blob + off) = (u64)(void *)(%sp + stack_off) */
-static void emit_rel_store_sp(struct bpf_gen *gen, int off, int stack_off)
+static void move_blob2blob(struct bpf_gen *gen, int off, int size, int blob_off)
{
- emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_10));
- emit(gen, BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, stack_off));
+ emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_2, BPF_PSEUDO_MAP_IDX_VALUE,
+ 0, 0, 0, blob_off));
+ emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_2, 0));
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
0, 0, 0, off));
- emit(gen, BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, 0));
+ emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_1, BPF_REG_0, 0));
+}
+
+static void move_blob2ctx(struct bpf_gen *gen, int ctx_off, int size, int blob_off)
+{
+ emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+ 0, 0, 0, blob_off));
+ emit(gen, BPF_LDX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_0, BPF_REG_1, 0));
+ emit(gen, BPF_STX_MEM(insn_bytes_to_bpf_size(size), BPF_REG_6, BPF_REG_0, ctx_off));
}
static void move_ctx2blob(struct bpf_gen *gen, int off, int size, int ctx_off,
offsetof(struct bpf_prog_desc, prog_fd), 4,
stack_off(prog_fd[i]));
for (i = 0; i < gen->nr_maps; i++)
- move_stack2ctx(gen,
- sizeof(struct bpf_loader_ctx) +
- sizeof(struct bpf_map_desc) * i +
- offsetof(struct bpf_map_desc, map_fd), 4,
- stack_off(map_fd[i]));
+ move_blob2ctx(gen,
+ sizeof(struct bpf_loader_ctx) +
+ sizeof(struct bpf_map_desc) * i +
+ offsetof(struct bpf_map_desc, map_fd), 4,
+ blob_fd_array_off(gen, i));
emit(gen, BPF_MOV64_IMM(BPF_REG_0, 0));
emit(gen, BPF_EXIT_INSN());
pr_debug("gen: finish %d\n", gen->error);
{
int attr_size = offsetofend(union bpf_attr, btf_vmlinux_value_type_id);
bool close_inner_map_fd = false;
- int map_create_attr;
+ int map_create_attr, idx;
union bpf_attr attr;
memset(&attr, 0, attr_size);
gen->error = -EDOM; /* internal bug */
return;
} else {
- emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_7,
- stack_off(map_fd[map_idx])));
- gen->nr_maps++;
+ /* add_map_fd does gen->nr_maps++ */
+ idx = add_map_fd(gen);
+ emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
+ 0, 0, 0, blob_fd_array_off(gen, idx)));
+ emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_1, BPF_REG_7, 0));
}
if (close_inner_map_fd)
emit_sys_close_stack(gen, stack_off(inner_map_fd));
*/
}
-void bpf_gen__record_extern(struct bpf_gen *gen, const char *name, int kind,
- int insn_idx)
+void bpf_gen__record_extern(struct bpf_gen *gen, const char *name, bool is_weak,
+ int kind, int insn_idx)
{
struct ksym_relo_desc *relo;
gen->relos = relo;
relo += gen->relo_cnt;
relo->name = name;
+ relo->is_weak = is_weak;
relo->kind = kind;
relo->insn_idx = insn_idx;
gen->relo_cnt++;
}
-static void emit_relo(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insns)
+/* returns existing ksym_desc with ref incremented, or inserts a new one */
+static struct ksym_desc *get_ksym_desc(struct bpf_gen *gen, struct ksym_relo_desc *relo)
{
- int name, insn, len = strlen(relo->name) + 1;
+ struct ksym_desc *kdesc;
- pr_debug("gen: emit_relo: %s at %d\n", relo->name, relo->insn_idx);
- name = add_data(gen, relo->name, len);
+ for (int i = 0; i < gen->nr_ksyms; i++) {
+ if (!strcmp(gen->ksyms[i].name, relo->name)) {
+ gen->ksyms[i].ref++;
+ return &gen->ksyms[i];
+ }
+ }
+ kdesc = libbpf_reallocarray(gen->ksyms, gen->nr_ksyms + 1, sizeof(*kdesc));
+ if (!kdesc) {
+ gen->error = -ENOMEM;
+ return NULL;
+ }
+ gen->ksyms = kdesc;
+ kdesc = &gen->ksyms[gen->nr_ksyms++];
+ kdesc->name = relo->name;
+ kdesc->kind = relo->kind;
+ kdesc->ref = 1;
+ kdesc->off = 0;
+ kdesc->insn = 0;
+ return kdesc;
+}
+
+/* Overwrites BPF_REG_{0, 1, 2, 3, 4, 7}
+ * Returns result in BPF_REG_7
+ */
+static void emit_bpf_find_by_name_kind(struct bpf_gen *gen, struct ksym_relo_desc *relo)
+{
+ int name_off, len = strlen(relo->name) + 1;
+ name_off = add_data(gen, relo->name, len);
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_1, BPF_PSEUDO_MAP_IDX_VALUE,
- 0, 0, 0, name));
+ 0, 0, 0, name_off));
emit(gen, BPF_MOV64_IMM(BPF_REG_2, len));
emit(gen, BPF_MOV64_IMM(BPF_REG_3, relo->kind));
emit(gen, BPF_MOV64_IMM(BPF_REG_4, 0));
emit(gen, BPF_EMIT_CALL(BPF_FUNC_btf_find_by_name_kind));
emit(gen, BPF_MOV64_REG(BPF_REG_7, BPF_REG_0));
debug_ret(gen, "find_by_name_kind(%s,%d)", relo->name, relo->kind);
- emit_check_err(gen);
+}
+
+/* Expects:
+ * BPF_REG_8 - pointer to instruction
+ *
+ * We need to reuse BTF fd for same symbol otherwise each relocation takes a new
+ * index, while kernel limits total kfunc BTFs to 256. For duplicate symbols,
+ * this would mean a new BTF fd index for each entry. By pairing symbol name
+ * with index, we get the insn->imm, insn->off pairing that kernel uses for
+ * kfunc_tab, which becomes the effective limit even though all of them may
+ * share same index in fd_array (such that kfunc_btf_tab has 1 element).
+ */
+static void emit_relo_kfunc_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insn)
+{
+ struct ksym_desc *kdesc;
+ int btf_fd_idx;
+
+ kdesc = get_ksym_desc(gen, relo);
+ if (!kdesc)
+ return;
+ /* try to copy from existing bpf_insn */
+ if (kdesc->ref > 1) {
+ move_blob2blob(gen, insn + offsetof(struct bpf_insn, imm), 4,
+ kdesc->insn + offsetof(struct bpf_insn, imm));
+ move_blob2blob(gen, insn + offsetof(struct bpf_insn, off), 2,
+ kdesc->insn + offsetof(struct bpf_insn, off));
+ goto log;
+ }
+ /* remember insn offset, so we can copy BTF ID and FD later */
+ kdesc->insn = insn;
+ emit_bpf_find_by_name_kind(gen, relo);
+ if (!relo->is_weak)
+ emit_check_err(gen);
+ /* get index in fd_array to store BTF FD at */
+ btf_fd_idx = add_kfunc_btf_fd(gen);
+ if (btf_fd_idx > INT16_MAX) {
+ pr_warn("BTF fd off %d for kfunc %s exceeds INT16_MAX, cannot process relocation\n",
+ btf_fd_idx, relo->name);
+ gen->error = -E2BIG;
+ return;
+ }
+ kdesc->off = btf_fd_idx;
+ /* set a default value for imm */
+ emit(gen, BPF_ST_MEM(BPF_W, BPF_REG_8, offsetof(struct bpf_insn, imm), 0));
+ /* skip success case store if ret < 0 */
+ emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, 1));
/* store btf_id into insn[insn_idx].imm */
- insn = insns + sizeof(struct bpf_insn) * relo->insn_idx +
- offsetof(struct bpf_insn, imm);
+ emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7, offsetof(struct bpf_insn, imm)));
+ /* load fd_array slot pointer */
emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
- 0, 0, 0, insn));
- emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_7, 0));
- if (relo->kind == BTF_KIND_VAR) {
- /* store btf_obj_fd into insn[insn_idx + 1].imm */
- emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_7, 32));
- emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_7,
- sizeof(struct bpf_insn)));
+ 0, 0, 0, blob_fd_array_off(gen, btf_fd_idx)));
+ /* skip store of BTF fd if ret < 0 */
+ emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, 3));
+ /* store BTF fd in slot */
+ emit(gen, BPF_MOV64_REG(BPF_REG_9, BPF_REG_7));
+ emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_9, 32));
+ emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_0, BPF_REG_9, 0));
+ /* set a default value for off */
+ emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), 0));
+ /* skip insn->off store if ret < 0 */
+ emit(gen, BPF_JMP_IMM(BPF_JSLT, BPF_REG_7, 0, 2));
+ /* skip if vmlinux BTF */
+ emit(gen, BPF_JMP_IMM(BPF_JEQ, BPF_REG_9, 0, 1));
+ /* store index into insn[insn_idx].off */
+ emit(gen, BPF_ST_MEM(BPF_H, BPF_REG_8, offsetof(struct bpf_insn, off), btf_fd_idx));
+log:
+ if (!gen->log_level)
+ return;
+ emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_8,
+ offsetof(struct bpf_insn, imm)));
+ emit(gen, BPF_LDX_MEM(BPF_H, BPF_REG_9, BPF_REG_8,
+ offsetof(struct bpf_insn, off)));
+ debug_regs(gen, BPF_REG_7, BPF_REG_9, " func (%s:count=%d): imm: %%d, off: %%d",
+ relo->name, kdesc->ref);
+ emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_0, BPF_PSEUDO_MAP_IDX_VALUE,
+ 0, 0, 0, blob_fd_array_off(gen, kdesc->off)));
+ emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_9, BPF_REG_0, 0));
+ debug_regs(gen, BPF_REG_9, -1, " func (%s:count=%d): btf_fd",
+ relo->name, kdesc->ref);
+}
+
+/* Expects:
+ * BPF_REG_8 - pointer to instruction
+ */
+static void emit_relo_ksym_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insn)
+{
+ struct ksym_desc *kdesc;
+
+ kdesc = get_ksym_desc(gen, relo);
+ if (!kdesc)
+ return;
+ /* try to copy from existing ldimm64 insn */
+ if (kdesc->ref > 1) {
+ move_blob2blob(gen, insn + offsetof(struct bpf_insn, imm), 4,
+ kdesc->insn + offsetof(struct bpf_insn, imm));
+ move_blob2blob(gen, insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm), 4,
+ kdesc->insn + sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm));
+ goto log;
+ }
+ /* remember insn offset, so we can copy BTF ID and FD later */
+ kdesc->insn = insn;
+ emit_bpf_find_by_name_kind(gen, relo);
+ emit_check_err(gen);
+ /* store btf_id into insn[insn_idx].imm */
+ emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7, offsetof(struct bpf_insn, imm)));
+ /* store btf_obj_fd into insn[insn_idx + 1].imm */
+ emit(gen, BPF_ALU64_IMM(BPF_RSH, BPF_REG_7, 32));
+ emit(gen, BPF_STX_MEM(BPF_W, BPF_REG_8, BPF_REG_7,
+ sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm)));
+log:
+ if (!gen->log_level)
+ return;
+ emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_7, BPF_REG_8,
+ offsetof(struct bpf_insn, imm)));
+ emit(gen, BPF_LDX_MEM(BPF_H, BPF_REG_9, BPF_REG_8, sizeof(struct bpf_insn) +
+ offsetof(struct bpf_insn, imm)));
+ debug_regs(gen, BPF_REG_7, BPF_REG_9, " var (%s:count=%d): imm: %%d, fd: %%d",
+ relo->name, kdesc->ref);
+}
+
+static void emit_relo(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insns)
+{
+ int insn;
+
+ pr_debug("gen: emit_relo (%d): %s at %d\n", relo->kind, relo->name, relo->insn_idx);
+ insn = insns + sizeof(struct bpf_insn) * relo->insn_idx;
+ emit2(gen, BPF_LD_IMM64_RAW_FULL(BPF_REG_8, BPF_PSEUDO_MAP_IDX_VALUE, 0, 0, 0, insn));
+ switch (relo->kind) {
+ case BTF_KIND_VAR:
+ emit_relo_ksym_btf(gen, relo, insn);
+ break;
+ case BTF_KIND_FUNC:
+ emit_relo_kfunc_btf(gen, relo, insn);
+ break;
+ default:
+ pr_warn("Unknown relocation kind '%d'\n", relo->kind);
+ gen->error = -EDOM;
+ return;
}
}
{
int i, insn;
- for (i = 0; i < gen->relo_cnt; i++) {
- if (gen->relos[i].kind != BTF_KIND_VAR)
- continue;
- /* close fd recorded in insn[insn_idx + 1].imm */
- insn = insns +
- sizeof(struct bpf_insn) * (gen->relos[i].insn_idx + 1) +
- offsetof(struct bpf_insn, imm);
- emit_sys_close_blob(gen, insn);
+ for (i = 0; i < gen->nr_ksyms; i++) {
+ if (gen->ksyms[i].kind == BTF_KIND_VAR) {
+ /* close fd recorded in insn[insn_idx + 1].imm */
+ insn = gen->ksyms[i].insn;
+ insn += sizeof(struct bpf_insn) + offsetof(struct bpf_insn, imm);
+ emit_sys_close_blob(gen, insn);
+ } else { /* BTF_KIND_FUNC */
+ emit_sys_close_blob(gen, blob_fd_array_off(gen, gen->ksyms[i].off));
+ if (gen->ksyms[i].off < MAX_FD_ARRAY_SZ)
+ gen->nr_fd_array--;
+ }
+ }
+ if (gen->nr_ksyms) {
+ free(gen->ksyms);
+ gen->nr_ksyms = 0;
+ gen->ksyms = NULL;
}
if (gen->relo_cnt) {
free(gen->relos);
/* populate union bpf_attr with a pointer to line_info */
emit_rel_store(gen, attr_field(prog_load_attr, line_info), line_info);
- /* populate union bpf_attr fd_array with a pointer to stack where map_fds are saved */
- emit_rel_store_sp(gen, attr_field(prog_load_attr, fd_array),
- stack_off(map_fd[0]));
+ /* populate union bpf_attr fd_array with a pointer to data where map_fds are saved */
+ emit_rel_store(gen, attr_field(prog_load_attr, fd_array), gen->fd_array);
/* populate union bpf_attr with user provided log details */
move_ctx2blob(gen, attr_field(prog_load_attr, log_level), 4,
emit(gen, BPF_EMIT_CALL(BPF_FUNC_copy_from_user));
map_update_attr = add_data(gen, &attr, attr_size);
- move_stack2blob(gen, attr_field(map_update_attr, map_fd), 4,
- stack_off(map_fd[map_idx]));
+ move_blob2blob(gen, attr_field(map_update_attr, map_fd), 4,
+ blob_fd_array_off(gen, map_idx));
emit_rel_store(gen, attr_field(map_update_attr, key), key);
emit_rel_store(gen, attr_field(map_update_attr, value), value);
/* emit MAP_UPDATE_ELEM command */
memset(&attr, 0, attr_size);
pr_debug("gen: map_freeze: idx %d\n", map_idx);
map_freeze_attr = add_data(gen, &attr, attr_size);
- move_stack2blob(gen, attr_field(map_freeze_attr, map_fd), 4,
- stack_off(map_fd[map_idx]));
+ move_blob2blob(gen, attr_field(map_freeze_attr, map_fd), 4,
+ blob_fd_array_off(gen, map_idx));
/* emit MAP_FREEZE command */
emit_sys_bpf(gen, BPF_MAP_FREEZE, map_freeze_attr, attr_size);
debug_ret(gen, "map_freeze");
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