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Commit 49b73fa6 authored by Alexei Starovoitov's avatar Alexei Starovoitov
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Merge branch 'bpf-arm64-add-support-for-bpf-arena' 

Puranjay Mohan says:

====================
bpf,arm64: Add support for BPF Arena

Changes in V4
V3: https://lore.kernel.org/bpf/20240323103057.26499-1-puranjay12@gmail.com/
- Use more descriptive variable names.
- Use insn_is_cast_user() helper.

Changes in V3
V2: https://lore.kernel.org/bpf/20240321153102.103832-1-puranjay12@gmail.com/
- Optimize bpf_addr_space_cast as suggested by Xu Kuohai

Changes in V2
V1: https://lore.kernel.org/bpf/20240314150003.123020-1-puranjay12@gmail.com/
- Fix build warnings by using 5 in place of 32 as DONT_CLEAR marker.
  R5 is not mapped to any BPF register so it can safely be used here.

This series adds the support for PROBE_MEM32 and bpf_addr_space_cast
instructions to the ARM64 BPF JIT. These two instructions allow the
enablement of BPF Arena.

All arena related selftests are passing.

  [root@ip-172-31-6-62 bpf]# ./test_progs -a "*arena*"
  #3/1     arena_htab/arena_htab_llvm:OK
  #3/2     arena_htab/arena_htab_asm:OK
  #3       arena_htab:OK
  #4/1     arena_list/arena_list_1:OK
  #4/2     arena_list/arena_list_1000:OK
  #4       arena_list:OK
  #434/1   verifier_arena/basic_alloc1:OK
  #434/2   verifier_arena/basic_alloc2:OK
  #434/3   verifier_arena/basic_alloc3:OK
  #434/4   verifier_arena/iter_maps1:OK
  #434/5   verifier_arena/iter_maps2:OK
  #434/6   verifier_arena/iter_maps3:OK
  #434     verifier_arena:OK
  Summary: 3/10 PASSED, 0 SKIPPED, 0 FAILED

This will need the patch [1] that introduced insn_is_cast_user() helper to
build.

The verifier_arena selftest could fail in the CI because the following
commit[2] is missing from bpf-next:

[1] https://lore.kernel.org/bpf/20240324183226.29674-1-puranjay12@gmail.com/
[2] https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=fa3550dca8f02ec312727653a94115ef3ab68445

Here is a CI run with all dependencies added: https://github.com/kernel-patches/bpf/pull/6641
====================

Link: https://lore.kernel.org/r/20240325150716.4387-1-puranjay12@gmail.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents c07b4bcd 4dd31243
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Showing with 76 additions and 12 deletions
arch/arm64/net/bpf_jit_comp.c
View file @ 49b73fa6
......@@ -29,6 +29,7 @@
#define TCALL_CNT (MAX_BPF_JIT_REG + 2)
#define TMP_REG_3 (MAX_BPF_JIT_REG + 3)
#define FP_BOTTOM (MAX_BPF_JIT_REG + 4)
#define ARENA_VM_START (MAX_BPF_JIT_REG + 5)
#define check_imm(bits, imm) do { \
if ((((imm) > 0) && ((imm) >> (bits))) || \
......@@ -67,6 +68,8 @@ static const int bpf2a64[] = {
/* temporary register for blinding constants */
[BPF_REG_AX] = A64_R(9),
[FP_BOTTOM] = A64_R(27),
/* callee saved register for kern_vm_start address */
[ARENA_VM_START] = A64_R(28),
};
struct jit_ctx {
......@@ -79,6 +82,7 @@ struct jit_ctx {
__le32 *ro_image;
u32 stack_size;
int fpb_offset;
u64 user_vm_start;
};
struct bpf_plt {
......@@ -295,7 +299,7 @@ static bool is_lsi_offset(int offset, int scale)
#define PROLOGUE_OFFSET (BTI_INSNS + 2 + PAC_INSNS + 8)
static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf,
bool is_exception_cb)
bool is_exception_cb, u64 arena_vm_start)
{
const struct bpf_prog *prog = ctx->prog;
const bool is_main_prog = !bpf_is_subprog(prog);
......@@ -306,6 +310,7 @@ static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf,
const u8 fp = bpf2a64[BPF_REG_FP];
const u8 tcc = bpf2a64[TCALL_CNT];
const u8 fpb = bpf2a64[FP_BOTTOM];
const u8 arena_vm_base = bpf2a64[ARENA_VM_START];
const int idx0 = ctx->idx;
int cur_offset;
......@@ -411,6 +416,10 @@ static int build_prologue(struct jit_ctx *ctx, bool ebpf_from_cbpf,
/* Set up function call stack */
emit(A64_SUB_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);
if (arena_vm_start)
emit_a64_mov_i64(arena_vm_base, arena_vm_start, ctx);
return 0;
}
......@@ -738,6 +747,7 @@ static void build_epilogue(struct jit_ctx *ctx, bool is_exception_cb)
#define BPF_FIXUP_OFFSET_MASK GENMASK(26, 0)
#define BPF_FIXUP_REG_MASK GENMASK(31, 27)
#define DONT_CLEAR 5 /* Unused ARM64 register from BPF's POV */
bool ex_handler_bpf(const struct exception_table_entry *ex,
struct pt_regs *regs)
......@@ -745,7 +755,8 @@ bool ex_handler_bpf(const struct exception_table_entry *ex,
off_t offset = FIELD_GET(BPF_FIXUP_OFFSET_MASK, ex->fixup);
int dst_reg = FIELD_GET(BPF_FIXUP_REG_MASK, ex->fixup);
regs->regs[dst_reg] = 0;
if (dst_reg != DONT_CLEAR)
regs->regs[dst_reg] = 0;
regs->pc = (unsigned long)&ex->fixup - offset;
return true;
}
......@@ -765,7 +776,8 @@ static int add_exception_handler(const struct bpf_insn *insn,
return 0;
if (BPF_MODE(insn->code) != BPF_PROBE_MEM &&
BPF_MODE(insn->code) != BPF_PROBE_MEMSX)
BPF_MODE(insn->code) != BPF_PROBE_MEMSX &&
BPF_MODE(insn->code) != BPF_PROBE_MEM32)
return 0;
if (!ctx->prog->aux->extable ||
......@@ -810,6 +822,9 @@ static int add_exception_handler(const struct bpf_insn *insn,
ex->insn = ins_offset;
if (BPF_CLASS(insn->code) != BPF_LDX)
dst_reg = DONT_CLEAR;
ex->fixup = FIELD_PREP(BPF_FIXUP_OFFSET_MASK, fixup_offset) |
FIELD_PREP(BPF_FIXUP_REG_MASK, dst_reg);
......@@ -829,12 +844,13 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
bool extra_pass)
{
const u8 code = insn->code;
const u8 dst = bpf2a64[insn->dst_reg];
const u8 src = bpf2a64[insn->src_reg];
u8 dst = bpf2a64[insn->dst_reg];
u8 src = bpf2a64[insn->src_reg];
const u8 tmp = bpf2a64[TMP_REG_1];
const u8 tmp2 = bpf2a64[TMP_REG_2];
const u8 fp = bpf2a64[BPF_REG_FP];
const u8 fpb = bpf2a64[FP_BOTTOM];
const u8 arena_vm_base = bpf2a64[ARENA_VM_START];
const s16 off = insn->off;
const s32 imm = insn->imm;
const int i = insn - ctx->prog->insnsi;
......@@ -853,6 +869,15 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
/* dst = src */
case BPF_ALU | BPF_MOV | BPF_X:
case BPF_ALU64 | BPF_MOV | BPF_X:
if (insn_is_cast_user(insn)) {
emit(A64_MOV(0, tmp, src), ctx); // 32-bit mov clears the upper 32 bits
emit_a64_mov_i(0, dst, ctx->user_vm_start >> 32, ctx);
emit(A64_LSL(1, dst, dst, 32), ctx);
emit(A64_CBZ(1, tmp, 2), ctx);
emit(A64_ORR(1, tmp, dst, tmp), ctx);
emit(A64_MOV(1, dst, tmp), ctx);
break;
}
switch (insn->off) {
case 0:
emit(A64_MOV(is64, dst, src), ctx);
......@@ -1237,7 +1262,15 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
case BPF_LDX | BPF_PROBE_MEMSX | BPF_B:
case BPF_LDX | BPF_PROBE_MEMSX | BPF_H:
case BPF_LDX | BPF_PROBE_MEMSX | BPF_W:
if (ctx->fpb_offset > 0 && src == fp) {
case BPF_LDX | BPF_PROBE_MEM32 | BPF_B:
case BPF_LDX | BPF_PROBE_MEM32 | BPF_H:
case BPF_LDX | BPF_PROBE_MEM32 | BPF_W:
case BPF_LDX | BPF_PROBE_MEM32 | BPF_DW:
if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) {
emit(A64_ADD(1, tmp2, src, arena_vm_base), ctx);
src = tmp2;
}
if (ctx->fpb_offset > 0 && src == fp && BPF_MODE(insn->code) != BPF_PROBE_MEM32) {
src_adj = fpb;
off_adj = off + ctx->fpb_offset;
} else {
......@@ -1322,7 +1355,15 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
case BPF_ST | BPF_MEM | BPF_H:
case BPF_ST | BPF_MEM | BPF_B:
case BPF_ST | BPF_MEM | BPF_DW:
if (ctx->fpb_offset > 0 && dst == fp) {
case BPF_ST | BPF_PROBE_MEM32 | BPF_B:
case BPF_ST | BPF_PROBE_MEM32 | BPF_H:
case BPF_ST | BPF_PROBE_MEM32 | BPF_W:
case BPF_ST | BPF_PROBE_MEM32 | BPF_DW:
if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) {
emit(A64_ADD(1, tmp2, dst, arena_vm_base), ctx);
dst = tmp2;
}
if (ctx->fpb_offset > 0 && dst == fp && BPF_MODE(insn->code) != BPF_PROBE_MEM32) {
dst_adj = fpb;
off_adj = off + ctx->fpb_offset;
} else {
......@@ -1365,6 +1406,10 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
}
break;
}
ret = add_exception_handler(insn, ctx, dst);
if (ret)
return ret;
break;
/* STX: *(size *)(dst + off) = src */
......@@ -1372,7 +1417,15 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
case BPF_STX | BPF_MEM | BPF_H:
case BPF_STX | BPF_MEM | BPF_B:
case BPF_STX | BPF_MEM | BPF_DW:
if (ctx->fpb_offset > 0 && dst == fp) {
case BPF_STX | BPF_PROBE_MEM32 | BPF_B:
case BPF_STX | BPF_PROBE_MEM32 | BPF_H:
case BPF_STX | BPF_PROBE_MEM32 | BPF_W:
case BPF_STX | BPF_PROBE_MEM32 | BPF_DW:
if (BPF_MODE(insn->code) == BPF_PROBE_MEM32) {
emit(A64_ADD(1, tmp2, dst, arena_vm_base), ctx);
dst = tmp2;
}
if (ctx->fpb_offset > 0 && dst == fp && BPF_MODE(insn->code) != BPF_PROBE_MEM32) {
dst_adj = fpb;
off_adj = off + ctx->fpb_offset;
} else {
......@@ -1413,6 +1466,10 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
}
break;
}
ret = add_exception_handler(insn, ctx, dst);
if (ret)
return ret;
break;
case BPF_STX | BPF_ATOMIC | BPF_W:
......@@ -1594,6 +1651,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
bool tmp_blinded = false;
bool extra_pass = false;
struct jit_ctx ctx;
u64 arena_vm_start;
u8 *image_ptr;
u8 *ro_image_ptr;
......@@ -1611,6 +1669,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
prog = tmp;
}
arena_vm_start = bpf_arena_get_kern_vm_start(prog->aux->arena);
jit_data = prog->aux->jit_data;
if (!jit_data) {
jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
......@@ -1641,6 +1700,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
}
ctx.fpb_offset = find_fpb_offset(prog);
ctx.user_vm_start = bpf_arena_get_user_vm_start(prog->aux->arena);
/*
* 1. Initial fake pass to compute ctx->idx and ctx->offset.
......@@ -1648,7 +1708,8 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
* BPF line info needs ctx->offset[i] to be the offset of
* instruction[i] in jited image, so build prologue first.
*/
if (build_prologue(&ctx, was_classic, prog->aux->exception_cb)) {
if (build_prologue(&ctx, was_classic, prog->aux->exception_cb,
arena_vm_start)) {
prog = orig_prog;
goto out_off;
}
......@@ -1696,7 +1757,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
ctx.idx = 0;
ctx.exentry_idx = 0;
build_prologue(&ctx, was_classic, prog->aux->exception_cb);
build_prologue(&ctx, was_classic, prog->aux->exception_cb, arena_vm_start);
if (build_body(&ctx, extra_pass)) {
prog = orig_prog;
......@@ -2461,6 +2522,11 @@ bool bpf_jit_supports_exceptions(void)
return true;
}
bool bpf_jit_supports_arena(void)
{
return true;
}
void bpf_jit_free(struct bpf_prog *prog)
{
if (prog->jited) {
......
tools/testing/selftests/bpf/DENYLIST.aarch64
View file @ 49b73fa6
......@@ -10,5 +10,3 @@ fill_link_info/kprobe_multi_link_info # bpf_program__attach_kprobe_mu
fill_link_info/kretprobe_multi_link_info # bpf_program__attach_kprobe_multi_opts unexpected error: -95
fill_link_info/kprobe_multi_invalid_ubuff # bpf_program__attach_kprobe_multi_opts unexpected error: -95
missed/kprobe_recursion # missed_kprobe_recursion__attach unexpected error: -95 (errno 95)
verifier_arena # JIT does not support arena
arena_htab # JIT does not support arena
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