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linux-stable/arch/loongarch/net/bpf_jit.c
Youling Tang dbcd7f5faf LoongArch: BPF: Add BPF exception tables 
Inspired by commit 800834285361("bpf, arm64: Add BPF exception tables"),
do similar to LoongArch to add BPF exception tables.

When a tracing BPF program attempts to read memory without using the
bpf_probe_read() helper, the verifier marks the load instruction with
the BPF_PROBE_MEM flag. Since the LoongArch JIT does not currently
recognize this flag it falls back to the interpreter.

Add support for BPF_PROBE_MEM, by appending an exception table to the
BPF program. If the load instruction causes a data abort, the fixup
infrastructure finds the exception table and fixes up the fault, by
clearing the destination register and jumping over the faulting
instruction.

To keep the compact exception table entry format, inspect the pc in
fixup_exception(). A more generic solution would add a "handler" field
to the table entry, like on x86, s390 and arm64, etc.

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2022-12-14 08:36:11 +08:00

1250 lines
31 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
/*
* BPF JIT compiler for LoongArch
*
* Copyright (C) 2022 Loongson Technology Corporation Limited
*/
#include "bpf_jit.h"
#define REG_TCC LOONGARCH_GPR_A6
#define TCC_SAVED LOONGARCH_GPR_S5
#define SAVE_RA BIT(0)
#define SAVE_TCC BIT(1)
static const int regmap[] = {
/* return value from in-kernel function, and exit value for eBPF program */
[BPF_REG_0] = LOONGARCH_GPR_A5,
/* arguments from eBPF program to in-kernel function */
[BPF_REG_1] = LOONGARCH_GPR_A0,
[BPF_REG_2] = LOONGARCH_GPR_A1,
[BPF_REG_3] = LOONGARCH_GPR_A2,
[BPF_REG_4] = LOONGARCH_GPR_A3,
[BPF_REG_5] = LOONGARCH_GPR_A4,
/* callee saved registers that in-kernel function will preserve */
[BPF_REG_6] = LOONGARCH_GPR_S0,
[BPF_REG_7] = LOONGARCH_GPR_S1,
[BPF_REG_8] = LOONGARCH_GPR_S2,
[BPF_REG_9] = LOONGARCH_GPR_S3,
/* read-only frame pointer to access stack */
[BPF_REG_FP] = LOONGARCH_GPR_S4,
/* temporary register for blinding constants */
[BPF_REG_AX] = LOONGARCH_GPR_T0,
};
static void mark_call(struct jit_ctx *ctx)
{
ctx->flags |= SAVE_RA;
}
static void mark_tail_call(struct jit_ctx *ctx)
{
ctx->flags |= SAVE_TCC;
}
static bool seen_call(struct jit_ctx *ctx)
{
return (ctx->flags & SAVE_RA);
}
static bool seen_tail_call(struct jit_ctx *ctx)
{
return (ctx->flags & SAVE_TCC);
}
static u8 tail_call_reg(struct jit_ctx *ctx)
{
if (seen_call(ctx))
return TCC_SAVED;
return REG_TCC;
}
/*
* eBPF prog stack layout:
*
* high
* original $sp ------------> +-------------------------+ <--LOONGARCH_GPR_FP
* | $ra |
* +-------------------------+
* | $fp |
* +-------------------------+
* | $s0 |
* +-------------------------+
* | $s1 |
* +-------------------------+
* | $s2 |
* +-------------------------+
* | $s3 |
* +-------------------------+
* | $s4 |
* +-------------------------+
* | $s5 |
* +-------------------------+ <--BPF_REG_FP
* | prog->aux->stack_depth |
* | (optional) |
* current $sp -------------> +-------------------------+
* low
*/
static void build_prologue(struct jit_ctx *ctx)
{
int stack_adjust = 0, store_offset, bpf_stack_adjust;
bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
/* To store ra, fp, s0, s1, s2, s3, s4 and s5. */
stack_adjust += sizeof(long) * 8;
stack_adjust = round_up(stack_adjust, 16);
stack_adjust += bpf_stack_adjust;
/*
* First instruction initializes the tail call count (TCC).
* On tail call we skip this instruction, and the TCC is
* passed in REG_TCC from the caller.
*/
emit_insn(ctx, addid, REG_TCC, LOONGARCH_GPR_ZERO, MAX_TAIL_CALL_CNT);
emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, -stack_adjust);
store_offset = stack_adjust - sizeof(long);
emit_insn(ctx, std, LOONGARCH_GPR_RA, LOONGARCH_GPR_SP, store_offset);
store_offset -= sizeof(long);
emit_insn(ctx, std, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, store_offset);
store_offset -= sizeof(long);
emit_insn(ctx, std, LOONGARCH_GPR_S0, LOONGARCH_GPR_SP, store_offset);
store_offset -= sizeof(long);
emit_insn(ctx, std, LOONGARCH_GPR_S1, LOONGARCH_GPR_SP, store_offset);
store_offset -= sizeof(long);
emit_insn(ctx, std, LOONGARCH_GPR_S2, LOONGARCH_GPR_SP, store_offset);
store_offset -= sizeof(long);
emit_insn(ctx, std, LOONGARCH_GPR_S3, LOONGARCH_GPR_SP, store_offset);
store_offset -= sizeof(long);
emit_insn(ctx, std, LOONGARCH_GPR_S4, LOONGARCH_GPR_SP, store_offset);
store_offset -= sizeof(long);
emit_insn(ctx, std, LOONGARCH_GPR_S5, LOONGARCH_GPR_SP, store_offset);
emit_insn(ctx, addid, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, stack_adjust);
if (bpf_stack_adjust)
emit_insn(ctx, addid, regmap[BPF_REG_FP], LOONGARCH_GPR_SP, bpf_stack_adjust);
/*
* Program contains calls and tail calls, so REG_TCC need
* to be saved across calls.
*/
if (seen_tail_call(ctx) && seen_call(ctx))
move_reg(ctx, TCC_SAVED, REG_TCC);
ctx->stack_size = stack_adjust;
}
static void __build_epilogue(struct jit_ctx *ctx, bool is_tail_call)
{
int stack_adjust = ctx->stack_size;
int load_offset;
load_offset = stack_adjust - sizeof(long);
emit_insn(ctx, ldd, LOONGARCH_GPR_RA, LOONGARCH_GPR_SP, load_offset);
load_offset -= sizeof(long);
emit_insn(ctx, ldd, LOONGARCH_GPR_FP, LOONGARCH_GPR_SP, load_offset);
load_offset -= sizeof(long);
emit_insn(ctx, ldd, LOONGARCH_GPR_S0, LOONGARCH_GPR_SP, load_offset);
load_offset -= sizeof(long);
emit_insn(ctx, ldd, LOONGARCH_GPR_S1, LOONGARCH_GPR_SP, load_offset);
load_offset -= sizeof(long);
emit_insn(ctx, ldd, LOONGARCH_GPR_S2, LOONGARCH_GPR_SP, load_offset);
load_offset -= sizeof(long);
emit_insn(ctx, ldd, LOONGARCH_GPR_S3, LOONGARCH_GPR_SP, load_offset);
load_offset -= sizeof(long);
emit_insn(ctx, ldd, LOONGARCH_GPR_S4, LOONGARCH_GPR_SP, load_offset);
load_offset -= sizeof(long);
emit_insn(ctx, ldd, LOONGARCH_GPR_S5, LOONGARCH_GPR_SP, load_offset);
emit_insn(ctx, addid, LOONGARCH_GPR_SP, LOONGARCH_GPR_SP, stack_adjust);
if (!is_tail_call) {
/* Set return value */
move_reg(ctx, LOONGARCH_GPR_A0, regmap[BPF_REG_0]);
/* Return to the caller */
emit_insn(ctx, jirl, LOONGARCH_GPR_RA, LOONGARCH_GPR_ZERO, 0);
} else {
/*
* Call the next bpf prog and skip the first instruction
* of TCC initialization.
*/
emit_insn(ctx, jirl, LOONGARCH_GPR_T3, LOONGARCH_GPR_ZERO, 1);
}
}
static void build_epilogue(struct jit_ctx *ctx)
{
__build_epilogue(ctx, false);
}
bool bpf_jit_supports_kfunc_call(void)
{
return true;
}
/* initialized on the first pass of build_body() */
static int out_offset = -1;
static int emit_bpf_tail_call(struct jit_ctx *ctx)
{
int off;
u8 tcc = tail_call_reg(ctx);
u8 a1 = LOONGARCH_GPR_A1;
u8 a2 = LOONGARCH_GPR_A2;
u8 t1 = LOONGARCH_GPR_T1;
u8 t2 = LOONGARCH_GPR_T2;
u8 t3 = LOONGARCH_GPR_T3;
const int idx0 = ctx->idx;
#define cur_offset (ctx->idx - idx0)
#define jmp_offset (out_offset - (cur_offset))
/*
* a0: &ctx
* a1: &array
* a2: index
*
* if (index >= array->map.max_entries)
* goto out;
*/
off = offsetof(struct bpf_array, map.max_entries);
emit_insn(ctx, ldwu, t1, a1, off);
/* bgeu $a2, $t1, jmp_offset */
if (emit_tailcall_jmp(ctx, BPF_JGE, a2, t1, jmp_offset) < 0)
goto toofar;
/*
* if (--TCC < 0)
* goto out;
*/
emit_insn(ctx, addid, REG_TCC, tcc, -1);
if (emit_tailcall_jmp(ctx, BPF_JSLT, REG_TCC, LOONGARCH_GPR_ZERO, jmp_offset) < 0)
goto toofar;
/*
* prog = array->ptrs[index];
* if (!prog)
* goto out;
*/
emit_insn(ctx, alsld, t2, a2, a1, 2);
off = offsetof(struct bpf_array, ptrs);
emit_insn(ctx, ldd, t2, t2, off);
/* beq $t2, $zero, jmp_offset */
if (emit_tailcall_jmp(ctx, BPF_JEQ, t2, LOONGARCH_GPR_ZERO, jmp_offset) < 0)
goto toofar;
/* goto *(prog->bpf_func + 4); */
off = offsetof(struct bpf_prog, bpf_func);
emit_insn(ctx, ldd, t3, t2, off);
__build_epilogue(ctx, true);
/* out: */
if (out_offset == -1)
out_offset = cur_offset;
if (cur_offset != out_offset) {
pr_err_once("tail_call out_offset = %d, expected %d!\n",
cur_offset, out_offset);
return -1;
}
return 0;
toofar:
pr_info_once("tail_call: jump too far\n");
return -1;
#undef cur_offset
#undef jmp_offset
}
static void emit_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
{
const u8 t1 = LOONGARCH_GPR_T1;
const u8 t2 = LOONGARCH_GPR_T2;
const u8 t3 = LOONGARCH_GPR_T3;
const u8 r0 = regmap[BPF_REG_0];
const u8 src = regmap[insn->src_reg];
const u8 dst = regmap[insn->dst_reg];
const s16 off = insn->off;
const s32 imm = insn->imm;
const bool isdw = BPF_SIZE(insn->code) == BPF_DW;
move_imm(ctx, t1, off, false);
emit_insn(ctx, addd, t1, dst, t1);
move_reg(ctx, t3, src);
switch (imm) {
/* lock *(size *)(dst + off) <op>= src */
case BPF_ADD:
if (isdw)
emit_insn(ctx, amaddd, t2, t1, src);
else
emit_insn(ctx, amaddw, t2, t1, src);
break;
case BPF_AND:
if (isdw)
emit_insn(ctx, amandd, t2, t1, src);
else
emit_insn(ctx, amandw, t2, t1, src);
break;
case BPF_OR:
if (isdw)
emit_insn(ctx, amord, t2, t1, src);
else
emit_insn(ctx, amorw, t2, t1, src);
break;
case BPF_XOR:
if (isdw)
emit_insn(ctx, amxord, t2, t1, src);
else
emit_insn(ctx, amxorw, t2, t1, src);
break;
/* src = atomic_fetch_<op>(dst + off, src) */
case BPF_ADD | BPF_FETCH:
if (isdw) {
emit_insn(ctx, amaddd, src, t1, t3);
} else {
emit_insn(ctx, amaddw, src, t1, t3);
emit_zext_32(ctx, src, true);
}
break;
case BPF_AND | BPF_FETCH:
if (isdw) {
emit_insn(ctx, amandd, src, t1, t3);
} else {
emit_insn(ctx, amandw, src, t1, t3);
emit_zext_32(ctx, src, true);
}
break;
case BPF_OR | BPF_FETCH:
if (isdw) {
emit_insn(ctx, amord, src, t1, t3);
} else {
emit_insn(ctx, amorw, src, t1, t3);
emit_zext_32(ctx, src, true);
}
break;
case BPF_XOR | BPF_FETCH:
if (isdw) {
emit_insn(ctx, amxord, src, t1, t3);
} else {
emit_insn(ctx, amxorw, src, t1, t3);
emit_zext_32(ctx, src, true);
}
break;
/* src = atomic_xchg(dst + off, src); */
case BPF_XCHG:
if (isdw) {
emit_insn(ctx, amswapd, src, t1, t3);
} else {
emit_insn(ctx, amswapw, src, t1, t3);
emit_zext_32(ctx, src, true);
}
break;
/* r0 = atomic_cmpxchg(dst + off, r0, src); */
case BPF_CMPXCHG:
move_reg(ctx, t2, r0);
if (isdw) {
emit_insn(ctx, lld, r0, t1, 0);
emit_insn(ctx, bne, t2, r0, 4);
move_reg(ctx, t3, src);
emit_insn(ctx, scd, t3, t1, 0);
emit_insn(ctx, beq, t3, LOONGARCH_GPR_ZERO, -4);
} else {
emit_insn(ctx, llw, r0, t1, 0);
emit_zext_32(ctx, t2, true);
emit_zext_32(ctx, r0, true);
emit_insn(ctx, bne, t2, r0, 4);
move_reg(ctx, t3, src);
emit_insn(ctx, scw, t3, t1, 0);
emit_insn(ctx, beq, t3, LOONGARCH_GPR_ZERO, -6);
emit_zext_32(ctx, r0, true);
}
break;
}
}
static bool is_signed_bpf_cond(u8 cond)
{
return cond == BPF_JSGT || cond == BPF_JSLT ||
cond == BPF_JSGE || cond == BPF_JSLE;
}
#define BPF_FIXUP_REG_MASK GENMASK(31, 27)
#define BPF_FIXUP_OFFSET_MASK GENMASK(26, 0)
bool ex_handler_bpf(const struct exception_table_entry *ex,
struct pt_regs *regs)
{
int dst_reg = FIELD_GET(BPF_FIXUP_REG_MASK, ex->fixup);
off_t offset = FIELD_GET(BPF_FIXUP_OFFSET_MASK, ex->fixup);
regs->regs[dst_reg] = 0;
regs->csr_era = (unsigned long)&ex->fixup - offset;
return true;
}
/* For accesses to BTF pointers, add an entry to the exception table */
static int add_exception_handler(const struct bpf_insn *insn,
struct jit_ctx *ctx,
int dst_reg)
{
unsigned long pc;
off_t offset;
struct exception_table_entry *ex;
if (!ctx->image || !ctx->prog->aux->extable || BPF_MODE(insn->code) != BPF_PROBE_MEM)
return 0;
if (WARN_ON_ONCE(ctx->num_exentries >= ctx->prog->aux->num_exentries))
return -EINVAL;
ex = &ctx->prog->aux->extable[ctx->num_exentries];
pc = (unsigned long)&ctx->image[ctx->idx - 1];
offset = pc - (long)&ex->insn;
if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN))
return -ERANGE;
ex->insn = offset;
/*
* Since the extable follows the program, the fixup offset is always
* negative and limited to BPF_JIT_REGION_SIZE. Store a positive value
* to keep things simple, and put the destination register in the upper
* bits. We don't need to worry about buildtime or runtime sort
* modifying the upper bits because the table is already sorted, and
* isn't part of the main exception table.
*/
offset = (long)&ex->fixup - (pc + LOONGARCH_INSN_SIZE);
if (!FIELD_FIT(BPF_FIXUP_OFFSET_MASK, offset))
return -ERANGE;
ex->type = EX_TYPE_BPF;
ex->fixup = FIELD_PREP(BPF_FIXUP_OFFSET_MASK, offset) | FIELD_PREP(BPF_FIXUP_REG_MASK, dst_reg);
ctx->num_exentries++;
return 0;
}
static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool extra_pass)
{
u8 tm = -1;
u64 func_addr;
bool func_addr_fixed;
int i = insn - ctx->prog->insnsi;
int ret, jmp_offset;
const u8 code = insn->code;
const u8 cond = BPF_OP(code);
const u8 t1 = LOONGARCH_GPR_T1;
const u8 t2 = LOONGARCH_GPR_T2;
const u8 src = regmap[insn->src_reg];
const u8 dst = regmap[insn->dst_reg];
const s16 off = insn->off;
const s32 imm = insn->imm;
const u64 imm64 = (u64)(insn + 1)->imm << 32 | (u32)insn->imm;
const bool is32 = BPF_CLASS(insn->code) == BPF_ALU || BPF_CLASS(insn->code) == BPF_JMP32;
switch (code) {
/* dst = src */
case BPF_ALU | BPF_MOV | BPF_X:
case BPF_ALU64 | BPF_MOV | BPF_X:
move_reg(ctx, dst, src);
emit_zext_32(ctx, dst, is32);
break;
/* dst = imm */
case BPF_ALU | BPF_MOV | BPF_K:
case BPF_ALU64 | BPF_MOV | BPF_K:
move_imm(ctx, dst, imm, is32);
break;
/* dst = dst + src */
case BPF_ALU | BPF_ADD | BPF_X:
case BPF_ALU64 | BPF_ADD | BPF_X:
emit_insn(ctx, addd, dst, dst, src);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst + imm */
case BPF_ALU | BPF_ADD | BPF_K:
case BPF_ALU64 | BPF_ADD | BPF_K:
if (is_signed_imm12(imm)) {
emit_insn(ctx, addid, dst, dst, imm);
} else {
move_imm(ctx, t1, imm, is32);
emit_insn(ctx, addd, dst, dst, t1);
}
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst - src */
case BPF_ALU | BPF_SUB | BPF_X:
case BPF_ALU64 | BPF_SUB | BPF_X:
emit_insn(ctx, subd, dst, dst, src);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst - imm */
case BPF_ALU | BPF_SUB | BPF_K:
case BPF_ALU64 | BPF_SUB | BPF_K:
if (is_signed_imm12(-imm)) {
emit_insn(ctx, addid, dst, dst, -imm);
} else {
move_imm(ctx, t1, imm, is32);
emit_insn(ctx, subd, dst, dst, t1);
}
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst * src */
case BPF_ALU | BPF_MUL | BPF_X:
case BPF_ALU64 | BPF_MUL | BPF_X:
emit_insn(ctx, muld, dst, dst, src);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst * imm */
case BPF_ALU | BPF_MUL | BPF_K:
case BPF_ALU64 | BPF_MUL | BPF_K:
move_imm(ctx, t1, imm, is32);
emit_insn(ctx, muld, dst, dst, t1);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst / src */
case BPF_ALU | BPF_DIV | BPF_X:
case BPF_ALU64 | BPF_DIV | BPF_X:
emit_zext_32(ctx, dst, is32);
move_reg(ctx, t1, src);
emit_zext_32(ctx, t1, is32);
emit_insn(ctx, divdu, dst, dst, t1);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst / imm */
case BPF_ALU | BPF_DIV | BPF_K:
case BPF_ALU64 | BPF_DIV | BPF_K:
move_imm(ctx, t1, imm, is32);
emit_zext_32(ctx, dst, is32);
emit_insn(ctx, divdu, dst, dst, t1);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst % src */
case BPF_ALU | BPF_MOD | BPF_X:
case BPF_ALU64 | BPF_MOD | BPF_X:
emit_zext_32(ctx, dst, is32);
move_reg(ctx, t1, src);
emit_zext_32(ctx, t1, is32);
emit_insn(ctx, moddu, dst, dst, t1);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst % imm */
case BPF_ALU | BPF_MOD | BPF_K:
case BPF_ALU64 | BPF_MOD | BPF_K:
move_imm(ctx, t1, imm, is32);
emit_zext_32(ctx, dst, is32);
emit_insn(ctx, moddu, dst, dst, t1);
emit_zext_32(ctx, dst, is32);
break;
/* dst = -dst */
case BPF_ALU | BPF_NEG:
case BPF_ALU64 | BPF_NEG:
move_imm(ctx, t1, imm, is32);
emit_insn(ctx, subd, dst, LOONGARCH_GPR_ZERO, dst);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst & src */
case BPF_ALU | BPF_AND | BPF_X:
case BPF_ALU64 | BPF_AND | BPF_X:
emit_insn(ctx, and, dst, dst, src);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst & imm */
case BPF_ALU | BPF_AND | BPF_K:
case BPF_ALU64 | BPF_AND | BPF_K:
if (is_unsigned_imm12(imm)) {
emit_insn(ctx, andi, dst, dst, imm);
} else {
move_imm(ctx, t1, imm, is32);
emit_insn(ctx, and, dst, dst, t1);
}
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst | src */
case BPF_ALU | BPF_OR | BPF_X:
case BPF_ALU64 | BPF_OR | BPF_X:
emit_insn(ctx, or, dst, dst, src);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst | imm */
case BPF_ALU | BPF_OR | BPF_K:
case BPF_ALU64 | BPF_OR | BPF_K:
if (is_unsigned_imm12(imm)) {
emit_insn(ctx, ori, dst, dst, imm);
} else {
move_imm(ctx, t1, imm, is32);
emit_insn(ctx, or, dst, dst, t1);
}
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst ^ src */
case BPF_ALU | BPF_XOR | BPF_X:
case BPF_ALU64 | BPF_XOR | BPF_X:
emit_insn(ctx, xor, dst, dst, src);
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst ^ imm */
case BPF_ALU | BPF_XOR | BPF_K:
case BPF_ALU64 | BPF_XOR | BPF_K:
if (is_unsigned_imm12(imm)) {
emit_insn(ctx, xori, dst, dst, imm);
} else {
move_imm(ctx, t1, imm, is32);
emit_insn(ctx, xor, dst, dst, t1);
}
emit_zext_32(ctx, dst, is32);
break;
/* dst = dst << src (logical) */
case BPF_ALU | BPF_LSH | BPF_X:
emit_insn(ctx, sllw, dst, dst, src);
emit_zext_32(ctx, dst, is32);
break;
case BPF_ALU64 | BPF_LSH | BPF_X:
emit_insn(ctx, slld, dst, dst, src);
break;
/* dst = dst << imm (logical) */
case BPF_ALU | BPF_LSH | BPF_K:
emit_insn(ctx, slliw, dst, dst, imm);
emit_zext_32(ctx, dst, is32);
break;
case BPF_ALU64 | BPF_LSH | BPF_K:
emit_insn(ctx, sllid, dst, dst, imm);
break;
/* dst = dst >> src (logical) */
case BPF_ALU | BPF_RSH | BPF_X:
emit_insn(ctx, srlw, dst, dst, src);
emit_zext_32(ctx, dst, is32);
break;
case BPF_ALU64 | BPF_RSH | BPF_X:
emit_insn(ctx, srld, dst, dst, src);
break;
/* dst = dst >> imm (logical) */
case BPF_ALU | BPF_RSH | BPF_K:
emit_insn(ctx, srliw, dst, dst, imm);
emit_zext_32(ctx, dst, is32);
break;
case BPF_ALU64 | BPF_RSH | BPF_K:
emit_insn(ctx, srlid, dst, dst, imm);
break;
/* dst = dst >> src (arithmetic) */
case BPF_ALU | BPF_ARSH | BPF_X:
emit_insn(ctx, sraw, dst, dst, src);
emit_zext_32(ctx, dst, is32);
break;
case BPF_ALU64 | BPF_ARSH | BPF_X:
emit_insn(ctx, srad, dst, dst, src);
break;
/* dst = dst >> imm (arithmetic) */
case BPF_ALU | BPF_ARSH | BPF_K:
emit_insn(ctx, sraiw, dst, dst, imm);
emit_zext_32(ctx, dst, is32);
break;
case BPF_ALU64 | BPF_ARSH | BPF_K:
emit_insn(ctx, sraid, dst, dst, imm);
break;
/* dst = BSWAP##imm(dst) */
case BPF_ALU | BPF_END | BPF_FROM_LE:
switch (imm) {
case 16:
/* zero-extend 16 bits into 64 bits */
emit_insn(ctx, bstrpickd, dst, dst, 15, 0);
break;
case 32:
/* zero-extend 32 bits into 64 bits */
emit_zext_32(ctx, dst, is32);
break;
case 64:
/* do nothing */
break;
}
break;
case BPF_ALU | BPF_END | BPF_FROM_BE:
switch (imm) {
case 16:
emit_insn(ctx, revb2h, dst, dst);
/* zero-extend 16 bits into 64 bits */
emit_insn(ctx, bstrpickd, dst, dst, 15, 0);
break;
case 32:
emit_insn(ctx, revb2w, dst, dst);
/* zero-extend 32 bits into 64 bits */
emit_zext_32(ctx, dst, is32);
break;
case 64:
emit_insn(ctx, revbd, dst, dst);
break;
}
break;
/* PC += off if dst cond src */
case BPF_JMP | BPF_JEQ | BPF_X:
case BPF_JMP | BPF_JNE | BPF_X:
case BPF_JMP | BPF_JGT | BPF_X:
case BPF_JMP | BPF_JGE | BPF_X:
case BPF_JMP | BPF_JLT | BPF_X:
case BPF_JMP | BPF_JLE | BPF_X:
case BPF_JMP | BPF_JSGT | BPF_X:
case BPF_JMP | BPF_JSGE | BPF_X:
case BPF_JMP | BPF_JSLT | BPF_X:
case BPF_JMP | BPF_JSLE | BPF_X:
case BPF_JMP32 | BPF_JEQ | BPF_X:
case BPF_JMP32 | BPF_JNE | BPF_X:
case BPF_JMP32 | BPF_JGT | BPF_X:
case BPF_JMP32 | BPF_JGE | BPF_X:
case BPF_JMP32 | BPF_JLT | BPF_X:
case BPF_JMP32 | BPF_JLE | BPF_X:
case BPF_JMP32 | BPF_JSGT | BPF_X:
case BPF_JMP32 | BPF_JSGE | BPF_X:
case BPF_JMP32 | BPF_JSLT | BPF_X:
case BPF_JMP32 | BPF_JSLE | BPF_X:
jmp_offset = bpf2la_offset(i, off, ctx);
move_reg(ctx, t1, dst);
move_reg(ctx, t2, src);
if (is_signed_bpf_cond(BPF_OP(code))) {
emit_sext_32(ctx, t1, is32);
emit_sext_32(ctx, t2, is32);
} else {
emit_zext_32(ctx, t1, is32);
emit_zext_32(ctx, t2, is32);
}
if (emit_cond_jmp(ctx, cond, t1, t2, jmp_offset) < 0)
goto toofar;
break;
/* PC += off if dst cond imm */
case BPF_JMP | BPF_JEQ | BPF_K:
case BPF_JMP | BPF_JNE | BPF_K:
case BPF_JMP | BPF_JGT | BPF_K:
case BPF_JMP | BPF_JGE | BPF_K:
case BPF_JMP | BPF_JLT | BPF_K:
case BPF_JMP | BPF_JLE | BPF_K:
case BPF_JMP | BPF_JSGT | BPF_K:
case BPF_JMP | BPF_JSGE | BPF_K:
case BPF_JMP | BPF_JSLT | BPF_K:
case BPF_JMP | BPF_JSLE | BPF_K:
case BPF_JMP32 | BPF_JEQ | BPF_K:
case BPF_JMP32 | BPF_JNE | BPF_K:
case BPF_JMP32 | BPF_JGT | BPF_K:
case BPF_JMP32 | BPF_JGE | BPF_K:
case BPF_JMP32 | BPF_JLT | BPF_K:
case BPF_JMP32 | BPF_JLE | BPF_K:
case BPF_JMP32 | BPF_JSGT | BPF_K:
case BPF_JMP32 | BPF_JSGE | BPF_K:
case BPF_JMP32 | BPF_JSLT | BPF_K:
case BPF_JMP32 | BPF_JSLE | BPF_K:
jmp_offset = bpf2la_offset(i, off, ctx);
if (imm) {
move_imm(ctx, t1, imm, false);
tm = t1;
} else {
/* If imm is 0, simply use zero register. */
tm = LOONGARCH_GPR_ZERO;
}
move_reg(ctx, t2, dst);
if (is_signed_bpf_cond(BPF_OP(code))) {
emit_sext_32(ctx, tm, is32);
emit_sext_32(ctx, t2, is32);
} else {
emit_zext_32(ctx, tm, is32);
emit_zext_32(ctx, t2, is32);
}
if (emit_cond_jmp(ctx, cond, t2, tm, jmp_offset) < 0)
goto toofar;
break;
/* PC += off if dst & src */
case BPF_JMP | BPF_JSET | BPF_X:
case BPF_JMP32 | BPF_JSET | BPF_X:
jmp_offset = bpf2la_offset(i, off, ctx);
emit_insn(ctx, and, t1, dst, src);
emit_zext_32(ctx, t1, is32);
if (emit_cond_jmp(ctx, cond, t1, LOONGARCH_GPR_ZERO, jmp_offset) < 0)
goto toofar;
break;
/* PC += off if dst & imm */
case BPF_JMP | BPF_JSET | BPF_K:
case BPF_JMP32 | BPF_JSET | BPF_K:
jmp_offset = bpf2la_offset(i, off, ctx);
move_imm(ctx, t1, imm, is32);
emit_insn(ctx, and, t1, dst, t1);
emit_zext_32(ctx, t1, is32);
if (emit_cond_jmp(ctx, cond, t1, LOONGARCH_GPR_ZERO, jmp_offset) < 0)
goto toofar;
break;
/* PC += off */
case BPF_JMP | BPF_JA:
jmp_offset = bpf2la_offset(i, off, ctx);
if (emit_uncond_jmp(ctx, jmp_offset) < 0)
goto toofar;
break;
/* function call */
case BPF_JMP | BPF_CALL:
mark_call(ctx);
ret = bpf_jit_get_func_addr(ctx->prog, insn, extra_pass,
&func_addr, &func_addr_fixed);
if (ret < 0)
return ret;
move_imm(ctx, t1, func_addr, is32);
emit_insn(ctx, jirl, t1, LOONGARCH_GPR_RA, 0);
move_reg(ctx, regmap[BPF_REG_0], LOONGARCH_GPR_A0);
break;
/* tail call */
case BPF_JMP | BPF_TAIL_CALL:
mark_tail_call(ctx);
if (emit_bpf_tail_call(ctx) < 0)
return -EINVAL;
break;
/* function return */
case BPF_JMP | BPF_EXIT:
emit_sext_32(ctx, regmap[BPF_REG_0], true);
if (i == ctx->prog->len - 1)
break;
jmp_offset = epilogue_offset(ctx);
if (emit_uncond_jmp(ctx, jmp_offset) < 0)
goto toofar;
break;
/* dst = imm64 */
case BPF_LD | BPF_IMM | BPF_DW:
move_imm(ctx, dst, imm64, is32);
return 1;
/* dst = *(size *)(src + off) */
case BPF_LDX | BPF_MEM | BPF_B:
case BPF_LDX | BPF_MEM | BPF_H:
case BPF_LDX | BPF_MEM | BPF_W:
case BPF_LDX | BPF_MEM | BPF_DW:
case BPF_LDX | BPF_PROBE_MEM | BPF_DW:
case BPF_LDX | BPF_PROBE_MEM | BPF_W:
case BPF_LDX | BPF_PROBE_MEM | BPF_H:
case BPF_LDX | BPF_PROBE_MEM | BPF_B:
switch (BPF_SIZE(code)) {
case BPF_B:
if (is_signed_imm12(off)) {
emit_insn(ctx, ldbu, dst, src, off);
} else {
move_imm(ctx, t1, off, is32);
emit_insn(ctx, ldxbu, dst, src, t1);
}
break;
case BPF_H:
if (is_signed_imm12(off)) {
emit_insn(ctx, ldhu, dst, src, off);
} else {
move_imm(ctx, t1, off, is32);
emit_insn(ctx, ldxhu, dst, src, t1);
}
break;
case BPF_W:
if (is_signed_imm12(off)) {
emit_insn(ctx, ldwu, dst, src, off);
} else if (is_signed_imm14(off)) {
emit_insn(ctx, ldptrw, dst, src, off);
} else {
move_imm(ctx, t1, off, is32);
emit_insn(ctx, ldxwu, dst, src, t1);
}
break;
case BPF_DW:
if (is_signed_imm12(off)) {
emit_insn(ctx, ldd, dst, src, off);
} else if (is_signed_imm14(off)) {
emit_insn(ctx, ldptrd, dst, src, off);
} else {
move_imm(ctx, t1, off, is32);
emit_insn(ctx, ldxd, dst, src, t1);
}
break;
}
ret = add_exception_handler(insn, ctx, dst);
if (ret)
return ret;
break;
/* *(size *)(dst + off) = imm */
case BPF_ST | BPF_MEM | BPF_B:
case BPF_ST | BPF_MEM | BPF_H:
case BPF_ST | BPF_MEM | BPF_W:
case BPF_ST | BPF_MEM | BPF_DW:
switch (BPF_SIZE(code)) {
case BPF_B:
move_imm(ctx, t1, imm, is32);
if (is_signed_imm12(off)) {
emit_insn(ctx, stb, t1, dst, off);
} else {
move_imm(ctx, t2, off, is32);
emit_insn(ctx, stxb, t1, dst, t2);
}
break;
case BPF_H:
move_imm(ctx, t1, imm, is32);
if (is_signed_imm12(off)) {
emit_insn(ctx, sth, t1, dst, off);
} else {
move_imm(ctx, t2, off, is32);
emit_insn(ctx, stxh, t1, dst, t2);
}
break;
case BPF_W:
move_imm(ctx, t1, imm, is32);
if (is_signed_imm12(off)) {
emit_insn(ctx, stw, t1, dst, off);
} else if (is_signed_imm14(off)) {
emit_insn(ctx, stptrw, t1, dst, off);
} else {
move_imm(ctx, t2, off, is32);
emit_insn(ctx, stxw, t1, dst, t2);
}
break;
case BPF_DW:
move_imm(ctx, t1, imm, is32);
if (is_signed_imm12(off)) {
emit_insn(ctx, std, t1, dst, off);
} else if (is_signed_imm14(off)) {
emit_insn(ctx, stptrd, t1, dst, off);
} else {
move_imm(ctx, t2, off, is32);
emit_insn(ctx, stxd, t1, dst, t2);
}
break;
}
break;
/* *(size *)(dst + off) = src */
case BPF_STX | BPF_MEM | BPF_B:
case BPF_STX | BPF_MEM | BPF_H:
case BPF_STX | BPF_MEM | BPF_W:
case BPF_STX | BPF_MEM | BPF_DW:
switch (BPF_SIZE(code)) {
case BPF_B:
if (is_signed_imm12(off)) {
emit_insn(ctx, stb, src, dst, off);
} else {
move_imm(ctx, t1, off, is32);
emit_insn(ctx, stxb, src, dst, t1);
}
break;
case BPF_H:
if (is_signed_imm12(off)) {
emit_insn(ctx, sth, src, dst, off);
} else {
move_imm(ctx, t1, off, is32);
emit_insn(ctx, stxh, src, dst, t1);
}
break;
case BPF_W:
if (is_signed_imm12(off)) {
emit_insn(ctx, stw, src, dst, off);
} else if (is_signed_imm14(off)) {
emit_insn(ctx, stptrw, src, dst, off);
} else {
move_imm(ctx, t1, off, is32);
emit_insn(ctx, stxw, src, dst, t1);
}
break;
case BPF_DW:
if (is_signed_imm12(off)) {
emit_insn(ctx, std, src, dst, off);
} else if (is_signed_imm14(off)) {
emit_insn(ctx, stptrd, src, dst, off);
} else {
move_imm(ctx, t1, off, is32);
emit_insn(ctx, stxd, src, dst, t1);
}
break;
}
break;
case BPF_STX | BPF_ATOMIC | BPF_W:
case BPF_STX | BPF_ATOMIC | BPF_DW:
emit_atomic(insn, ctx);
break;
default:
pr_err("bpf_jit: unknown opcode %02x\n", code);
return -EINVAL;
}
return 0;
toofar:
pr_info_once("bpf_jit: opcode %02x, jump too far\n", code);
return -E2BIG;
}
static int build_body(struct jit_ctx *ctx, bool extra_pass)
{
int i;
const struct bpf_prog *prog = ctx->prog;
for (i = 0; i < prog->len; i++) {
const struct bpf_insn *insn = &prog->insnsi[i];
int ret;
if (ctx->image == NULL)
ctx->offset[i] = ctx->idx;
ret = build_insn(insn, ctx, extra_pass);
if (ret > 0) {
i++;
if (ctx->image == NULL)
ctx->offset[i] = ctx->idx;
continue;
}
if (ret)
return ret;
}
if (ctx->image == NULL)
ctx->offset[i] = ctx->idx;
return 0;
}
/* Fill space with break instructions */
static void jit_fill_hole(void *area, unsigned int size)
{
u32 *ptr;
/* We are guaranteed to have aligned memory */
for (ptr = area; size >= sizeof(u32); size -= sizeof(u32))
*ptr++ = INSN_BREAK;
}
static int validate_code(struct jit_ctx *ctx)
{
int i;
union loongarch_instruction insn;
for (i = 0; i < ctx->idx; i++) {
insn = ctx->image[i];
/* Check INSN_BREAK */
if (insn.word == INSN_BREAK)
return -1;
}
if (WARN_ON_ONCE(ctx->num_exentries != ctx->prog->aux->num_exentries))
return -1;
return 0;
}
struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
{
bool tmp_blinded = false, extra_pass = false;
u8 *image_ptr;
int image_size, prog_size, extable_size;
struct jit_ctx ctx;
struct jit_data *jit_data;
struct bpf_binary_header *header;
struct bpf_prog *tmp, *orig_prog = prog;
/*
* If BPF JIT was not enabled then we must fall back to
* the interpreter.
*/
if (!prog->jit_requested)
return orig_prog;
tmp = bpf_jit_blind_constants(prog);
/*
* If blinding was requested and we failed during blinding,
* we must fall back to the interpreter. Otherwise, we save
* the new JITed code.
*/
if (IS_ERR(tmp))
return orig_prog;
if (tmp != prog) {
tmp_blinded = true;
prog = tmp;
}
jit_data = prog->aux->jit_data;
if (!jit_data) {
jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
if (!jit_data) {
prog = orig_prog;
goto out;
}
prog->aux->jit_data = jit_data;
}
if (jit_data->ctx.offset) {
ctx = jit_data->ctx;
image_ptr = jit_data->image;
header = jit_data->header;
extra_pass = true;
prog_size = sizeof(u32) * ctx.idx;
goto skip_init_ctx;
}
memset(&ctx, 0, sizeof(ctx));
ctx.prog = prog;
ctx.offset = kvcalloc(prog->len + 1, sizeof(u32), GFP_KERNEL);
if (ctx.offset == NULL) {
prog = orig_prog;
goto out_offset;
}
/* 1. Initial fake pass to compute ctx->idx and set ctx->flags */
build_prologue(&ctx);
if (build_body(&ctx, extra_pass)) {
prog = orig_prog;
goto out_offset;
}
ctx.epilogue_offset = ctx.idx;
build_epilogue(&ctx);
extable_size = prog->aux->num_exentries * sizeof(struct exception_table_entry);
/* Now we know the actual image size.
* As each LoongArch instruction is of length 32bit,
* we are translating number of JITed intructions into
* the size required to store these JITed code.
*/
prog_size = sizeof(u32) * ctx.idx;
image_size = prog_size + extable_size;
/* Now we know the size of the structure to make */
header = bpf_jit_binary_alloc(image_size, &image_ptr,
sizeof(u32), jit_fill_hole);
if (header == NULL) {
prog = orig_prog;
goto out_offset;
}
/* 2. Now, the actual pass to generate final JIT code */
ctx.image = (union loongarch_instruction *)image_ptr;
if (extable_size)
prog->aux->extable = (void *)image_ptr + prog_size;
skip_init_ctx:
ctx.idx = 0;
ctx.num_exentries = 0;
build_prologue(&ctx);
if (build_body(&ctx, extra_pass)) {
bpf_jit_binary_free(header);
prog = orig_prog;
goto out_offset;
}
build_epilogue(&ctx);
/* 3. Extra pass to validate JITed code */
if (validate_code(&ctx)) {
bpf_jit_binary_free(header);
prog = orig_prog;
goto out_offset;
}
/* And we're done */
if (bpf_jit_enable > 1)
bpf_jit_dump(prog->len, prog_size, 2, ctx.image);
/* Update the icache */
flush_icache_range((unsigned long)header, (unsigned long)(ctx.image + ctx.idx));
if (!prog->is_func || extra_pass) {
if (extra_pass && ctx.idx != jit_data->ctx.idx) {
pr_err_once("multi-func JIT bug %d != %d\n",
ctx.idx, jit_data->ctx.idx);
bpf_jit_binary_free(header);
prog->bpf_func = NULL;
prog->jited = 0;
prog->jited_len = 0;
goto out_offset;
}
bpf_jit_binary_lock_ro(header);
} else {
jit_data->ctx = ctx;
jit_data->image = image_ptr;
jit_data->header = header;
}
prog->jited = 1;
prog->jited_len = prog_size;
prog->bpf_func = (void *)ctx.image;
if (!prog->is_func || extra_pass) {
int i;
/* offset[prog->len] is the size of program */
for (i = 0; i <= prog->len; i++)
ctx.offset[i] *= LOONGARCH_INSN_SIZE;
bpf_prog_fill_jited_linfo(prog, ctx.offset + 1);
out_offset:
kvfree(ctx.offset);
kfree(jit_data);
prog->aux->jit_data = NULL;
}
out:
if (tmp_blinded)
bpf_jit_prog_release_other(prog, prog == orig_prog ? tmp : orig_prog);
out_offset = -1;
return prog;
}
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