/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * bpf_jit.h: BPF JIT compiler for PPC
 *
 * Copyright 2011 Matt Evans <matt@ozlabs.org>, IBM Corporation
 *           2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
 */
#ifndef _BPF_JIT_H
#define _BPF_JIT_H

#ifndef __ASSEMBLER__

#include <asm/types.h>
#include <asm/ppc-opcode.h>
#include <linux/build_bug.h>

#ifdef CONFIG_PPC64_ELF_ABI_V1
#define FUNCTION_DESCR_SIZE     24
#else
#define FUNCTION_DESCR_SIZE     0
#endif

#define CTX_NIA(ctx) ((unsigned long)ctx->idx * 4)

#define SZL                     sizeof(unsigned long)
#define BPF_INSN_SAFETY         64
#define BPF_PPC_TAILCALL        8

#define PLANT_INSTR(d, idx, instr)                                            \
        do { if (d) { (d)[idx] = instr; } idx++; } while (0)
#define EMIT(instr)             PLANT_INSTR(image, ctx->idx, instr)

/* Long jump; (unconditional 'branch') */
#define PPC_JMP(dest)                                                         \
        do {                                                                  \
                long offset = (long)(dest) - CTX_NIA(ctx);                    \
                if ((dest) != 0 && !is_offset_in_branch_range(offset)) {                      \
                        pr_err_ratelimited("Branch offset 0x%lx (@%u) out of range\n", offset, ctx->idx);                       \
                        return -ERANGE;                                       \
                }                                                             \
                EMIT(PPC_RAW_BRANCH(offset));                                 \
        } while (0)

/* "cond" here covers BO:BI fields. */
#define PPC_BCC_SHORT(cond, dest)                                             \
        do {                                                                  \
                long offset = (long)(dest) - CTX_NIA(ctx);                    \
                if ((dest) != 0 && !is_offset_in_cond_branch_range(offset)) {                 \
                        pr_err_ratelimited("Conditional branch offset 0x%lx (@%u) out of range\n", offset, ctx->idx);           \
                        return -ERANGE;                                       \
                }                                                             \
                EMIT(PPC_INST_BRANCH_COND | (((cond) & 0x3ff) << 16) | (offset & 0xfffc));                                      \
        } while (0)

/* When constant jump offset is known prior */
#define PPC_BCC_CONST_SHORT(cond, offset)                                                       \
        do {                                                                                    \
                BUILD_BUG_ON(offset < -0x8000 || offset > 0x7fff || (offset & 0x3));            \
                EMIT(PPC_INST_BRANCH_COND | (((cond) & 0x3ff) << 16) | (offset & 0xfffc));      \
        } while (0)

/*
 * Sign-extended 32-bit immediate load
 *
 * If this is a dummy pass (!image), account for
 * maximum possible instructions.
 */
#define PPC_LI32(d, i)          do {                                          \
        if (!image)                                                           \
                ctx->idx += 2;                                                \
        else {                                                                \
                if ((int)(uintptr_t)(i) >= -32768 &&                          \
                                (int)(uintptr_t)(i) < 32768)                  \
                        EMIT(PPC_RAW_LI(d, i));                               \
                else {                                                        \
                        EMIT(PPC_RAW_LIS(d, IMM_H(i)));                       \
                        if (IMM_L(i))                                         \
                                EMIT(PPC_RAW_ORI(d, d, IMM_L(i)));            \
                }                                                             \
        } } while (0)

#ifdef CONFIG_PPC64

/* If dummy pass (!image), account for maximum possible instructions */
#define PPC_LI64(d, i)          do {                                          \
        if (!image)                                                           \
                ctx->idx += 5;                                                \
        else {                                                                \
                if ((long)(i) >= -2147483648 &&                               \
                                (long)(i) < 2147483648)                       \
                        PPC_LI32(d, i);                                       \
                else {                                                        \
                        if (!((uintptr_t)(i) & 0xffff800000000000ULL))        \
                                EMIT(PPC_RAW_LI(d, ((uintptr_t)(i) >> 32) &   \
                                                0xffff));                     \
                        else {                                                \
                                EMIT(PPC_RAW_LIS(d, ((uintptr_t)(i) >> 48))); \
                                if ((uintptr_t)(i) & 0x0000ffff00000000ULL)   \
                                        EMIT(PPC_RAW_ORI(d, d,                \
                                          ((uintptr_t)(i) >> 32) & 0xffff));  \
                        }                                                     \
                        EMIT(PPC_RAW_SLDI(d, d, 32));                         \
                        if ((uintptr_t)(i) & 0x00000000ffff0000ULL)           \
                                EMIT(PPC_RAW_ORIS(d, d,                       \
                                         ((uintptr_t)(i) >> 16) & 0xffff));   \
                        if ((uintptr_t)(i) & 0x000000000000ffffULL)           \
                                EMIT(PPC_RAW_ORI(d, d, (uintptr_t)(i) &       \
                                                        0xffff));             \
                }                                                             \
        } } while (0)
#define PPC_LI_ADDR     PPC_LI64

#ifndef CONFIG_PPC_KERNEL_PCREL
#define PPC64_LOAD_PACA()                                                     \
        EMIT(PPC_RAW_LD(_R2, _R13, offsetof(struct paca_struct, kernel_toc)))
#else
#define PPC64_LOAD_PACA()       do {} while (0)
#endif
#else
#define PPC_LI64(d, i)  BUILD_BUG()
#define PPC_LI_ADDR     PPC_LI32
#define PPC64_LOAD_PACA() BUILD_BUG()
#endif

/*
 * The fly in the ointment of code size changing from pass to pass is
 * avoided by padding the short branch case with a NOP.  If code size differs
 * with different branch reaches we will have the issue of code moving from
 * one pass to the next and will need a few passes to converge on a stable
 * state.
 */
#define PPC_BCC(cond, dest)     do {                                          \
                if (is_offset_in_cond_branch_range((long)(dest) - CTX_NIA(ctx))) {      \
                        PPC_BCC_SHORT(cond, dest);                            \
                        EMIT(PPC_RAW_NOP());                                  \
                } else {                                                      \
                        /* Flip the 'T or F' bit to invert comparison */      \
                        PPC_BCC_SHORT(cond ^ COND_CMP_TRUE, CTX_NIA(ctx) + 2*4);  \
                        PPC_JMP(dest);                                        \
                } } while(0)

/* To create a branch condition, select a bit of cr0... */
#define CR0_LT          0
#define CR0_GT          1
#define CR0_EQ          2
/* ...and modify BO[3] */
#define COND_CMP_TRUE   0x100
#define COND_CMP_FALSE  0x000
/* Together, they make all required comparisons: */
#define COND_GT         (CR0_GT | COND_CMP_TRUE)
#define COND_GE         (CR0_LT | COND_CMP_FALSE)
#define COND_EQ         (CR0_EQ | COND_CMP_TRUE)
#define COND_NE         (CR0_EQ | COND_CMP_FALSE)
#define COND_LT         (CR0_LT | COND_CMP_TRUE)
#define COND_LE         (CR0_GT | COND_CMP_FALSE)

#define SEEN_FUNC       0x20000000 /* might call external helpers */
#define SEEN_TAILCALL   0x40000000 /* uses tail calls */

struct codegen_context {
        /*
         * This is used to track register usage as well
         * as calls to external helpers.
         * - register usage is tracked with corresponding
         *   bits (r3-r31)
         * - rest of the bits can be used to track other
         *   things -- for now, we use bits 0 to 2
         *   encoded in SEEN_* macros above
         */
        unsigned int seen;
        unsigned int idx;
        unsigned int stack_size;
        int b2p[MAX_BPF_JIT_REG + 3];
        unsigned int exentry_idx;
        unsigned int alt_exit_addr;
        u64 arena_vm_start;
        u64 user_vm_start;
        bool is_subprog;
        bool exception_boundary;
        bool exception_cb;
};

#define bpf_to_ppc(r)   (ctx->b2p[r])

#ifdef CONFIG_PPC32
#define BPF_FIXUP_LEN   3 /* Three instructions => 12 bytes */
#else
#define BPF_FIXUP_LEN   2 /* Two instructions => 8 bytes */
#endif

static inline bool bpf_is_seen_register(struct codegen_context *ctx, int i)
{
        return ctx->seen & (1 << (31 - i));
}

static inline void bpf_set_seen_register(struct codegen_context *ctx, int i)
{
        ctx->seen |= 1 << (31 - i);
}

static inline void bpf_clear_seen_register(struct codegen_context *ctx, int i)
{
        ctx->seen &= ~(1 << (31 - i));
}

void bpf_jit_init_reg_mapping(struct codegen_context *ctx);
int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context *ctx, u64 func);
int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct codegen_context *ctx,
                       u32 *addrs, int pass, bool extra_pass);
void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx);
void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx);
void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx);
void bpf_jit_realloc_regs(struct codegen_context *ctx);
int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr);

int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, u32 *fimage, int pass,
                          struct codegen_context *ctx, int insn_idx,
                          int jmp_off, int dst_reg, u32 code);
#endif

#endif