arch/powerpc/net/bpf_jit_comp.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * eBPF JIT compiler
  *
  * Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
  *		  IBM Corporation
  *
  * Based on the powerpc classic BPF JIT compiler by Matt Evans
  */
 #include <linux/moduleloader.h>
 #include <asm/cacheflush.h>
 #include <asm/asm-compat.h>
 #include <linux/netdevice.h>
 #include <linux/filter.h>
 #include <linux/if_vlan.h>
 #include <asm/kprobes.h>
 #include <linux/bpf.h>

 #include "bpf_jit.h"

 static void bpf_jit_fill_ill_insns(void *area, unsigned int size)
 {
 	memset32(area, BREAKPOINT_INSTRUCTION, size / 4);
 }

 /* Fix updated addresses (for subprog calls, ldimm64, et al) during extra pass */
 static int bpf_jit_fixup_addresses(struct bpf_prog *fp, u32 *image,
 				   struct codegen_context *ctx, u32 *addrs)
 {
 	const struct bpf_insn *insn = fp->insnsi;
 	bool func_addr_fixed;
 	u64 func_addr;
 	u32 tmp_idx;
 	int i, j, ret;

 	for (i = 0; i < fp->len; i++) {
 		/*
 		 * During the extra pass, only the branch target addresses for
 		 * the subprog calls need to be fixed. All other instructions
 		 * can left untouched.
 		 *
 		 * The JITed image length does not change because we already
 		 * ensure that the JITed instruction sequence for these calls
 		 * are of fixed length by padding them with NOPs.
 		 */
 		if (insn[i].code == (BPF_JMP | BPF_CALL) &&
 		    insn[i].src_reg == BPF_PSEUDO_CALL) {
 			ret = bpf_jit_get_func_addr(fp, &insn[i], true,
 						    &func_addr,
 						    &func_addr_fixed);
 			if (ret < 0)
 				return ret;

 			/*
 			 * Save ctx->idx as this would currently point to the
 			 * end of the JITed image and set it to the offset of
 			 * the instruction sequence corresponding to the
 			 * subprog call temporarily.
 			 */
 			tmp_idx = ctx->idx;
 			ctx->idx = addrs[i] / 4;
 			ret = bpf_jit_emit_func_call_rel(image, ctx, func_addr);
 			if (ret)
 				return ret;

 			/*
 			 * Restore ctx->idx here. This is safe as the length
 			 * of the JITed sequence remains unchanged.
 			 */
 			ctx->idx = tmp_idx;
 		} else if (insn[i].code == (BPF_LD | BPF_IMM | BPF_DW)) {
 			tmp_idx = ctx->idx;
 			ctx->idx = addrs[i] / 4;
 #ifdef CONFIG_PPC32
 			PPC_LI32(bpf_to_ppc(insn[i].dst_reg) - 1, (u32)insn[i + 1].imm);
 			PPC_LI32(bpf_to_ppc(insn[i].dst_reg), (u32)insn[i].imm);
 			for (j = ctx->idx - addrs[i] / 4; j < 4; j++)
 				EMIT(PPC_RAW_NOP());
 #else
 			func_addr = ((u64)(u32)insn[i].imm) | (((u64)(u32)insn[i + 1].imm) << 32);
 			PPC_LI64(bpf_to_ppc(insn[i].dst_reg), func_addr);
 			/* overwrite rest with nops */
 			for (j = ctx->idx - addrs[i] / 4; j < 5; j++)
 				EMIT(PPC_RAW_NOP());
 #endif
 			ctx->idx = tmp_idx;
 			i++;
 		}
 	}

 	return 0;
 }

 int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr)
 {
 	if (!exit_addr || is_offset_in_branch_range(exit_addr - (ctx->idx * 4))) {
 		PPC_JMP(exit_addr);
 	} else if (ctx->alt_exit_addr) {
 		if (WARN_ON(!is_offset_in_branch_range((long)ctx->alt_exit_addr - (ctx->idx * 4))))
 			return -1;
 		PPC_JMP(ctx->alt_exit_addr);
 	} else {
 		ctx->alt_exit_addr = ctx->idx * 4;
 		bpf_jit_build_epilogue(image, ctx);
 	}

 	return 0;
 }

 struct powerpc64_jit_data {
 	struct bpf_binary_header *header;
 	u32 *addrs;
 	u8 *image;
 	u32 proglen;
 	struct codegen_context ctx;
 };

 bool bpf_jit_needs_zext(void)
 {
 	return true;
 }

 struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
 {
 	u32 proglen;
 	u32 alloclen;
 	u8 *image = NULL;
 	u32 *code_base;
 	u32 *addrs;
 	struct powerpc64_jit_data *jit_data;
 	struct codegen_context cgctx;
 	int pass;
 	int flen;
 	struct bpf_binary_header *bpf_hdr;
 	struct bpf_prog *org_fp = fp;
 	struct bpf_prog *tmp_fp;
 	bool bpf_blinded = false;
 	bool extra_pass = false;
 	u32 extable_len;
 	u32 fixup_len;

 	if (!fp->jit_requested)
 		return org_fp;

 	tmp_fp = bpf_jit_blind_constants(org_fp);
 	if (IS_ERR(tmp_fp))
 		return org_fp;

 	if (tmp_fp != org_fp) {
 		bpf_blinded = true;
 		fp = tmp_fp;
 	}

 	jit_data = fp->aux->jit_data;
 	if (!jit_data) {
 		jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
 		if (!jit_data) {
 			fp = org_fp;
 			goto out;
 		}
 		fp->aux->jit_data = jit_data;
 	}

 	flen = fp->len;
 	addrs = jit_data->addrs;
 	if (addrs) {
 		cgctx = jit_data->ctx;
 		image = jit_data->image;
 		bpf_hdr = jit_data->header;
 		proglen = jit_data->proglen;
 		extra_pass = true;
 		goto skip_init_ctx;
 	}

 	addrs = kcalloc(flen + 1, sizeof(*addrs), GFP_KERNEL);
 	if (addrs == NULL) {
 		fp = org_fp;
 		goto out_addrs;
 	}

 	memset(&cgctx, 0, sizeof(struct codegen_context));
 	bpf_jit_init_reg_mapping(&cgctx);

 	/* Make sure that the stack is quadword aligned. */
 	cgctx.stack_size = round_up(fp->aux->stack_depth, 16);

 	/* Scouting faux-generate pass 0 */
 	if (bpf_jit_build_body(fp, 0, &cgctx, addrs, 0)) {
 		/* We hit something illegal or unsupported. */
 		fp = org_fp;
 		goto out_addrs;
 	}

 	/*
 	 * If we have seen a tail call, we need a second pass.
 	 * This is because bpf_jit_emit_common_epilogue() is called
 	 * from bpf_jit_emit_tail_call() with a not yet stable ctx->seen.
 	 * We also need a second pass if we ended up with too large
 	 * a program so as to ensure BPF_EXIT branches are in range.
 	 */
 	if (cgctx.seen & SEEN_TAILCALL || !is_offset_in_branch_range((long)cgctx.idx * 4)) {
 		cgctx.idx = 0;
 		if (bpf_jit_build_body(fp, 0, &cgctx, addrs, 0)) {
 			fp = org_fp;
 			goto out_addrs;
 		}
 	}

 	bpf_jit_realloc_regs(&cgctx);
 	/*
 	 * Pretend to build prologue, given the features we've seen.  This will
 	 * update ctgtx.idx as it pretends to output instructions, then we can
 	 * calculate total size from idx.
 	 */
 	bpf_jit_build_prologue(0, &cgctx);
 	addrs[fp->len] = cgctx.idx * 4;
 	bpf_jit_build_epilogue(0, &cgctx);

 	fixup_len = fp->aux->num_exentries * BPF_FIXUP_LEN * 4;
 	extable_len = fp->aux->num_exentries * sizeof(struct exception_table_entry);

 	proglen = cgctx.idx * 4;
 	alloclen = proglen + FUNCTION_DESCR_SIZE + fixup_len + extable_len;

 	bpf_hdr = bpf_jit_binary_alloc(alloclen, &image, 4, bpf_jit_fill_ill_insns);
 	if (!bpf_hdr) {
 		fp = org_fp;
 		goto out_addrs;
 	}

 	if (extable_len)
 		fp->aux->extable = (void *)image + FUNCTION_DESCR_SIZE + proglen + fixup_len;

 skip_init_ctx:
 	code_base = (u32 *)(image + FUNCTION_DESCR_SIZE);

 	if (extra_pass) {
 		/*
 		 * Do not touch the prologue and epilogue as they will remain
 		 * unchanged. Only fix the branch target address for subprog
 		 * calls in the body, and ldimm64 instructions.
 		 *
 		 * This does not change the offsets and lengths of the subprog
 		 * call instruction sequences and hence, the size of the JITed
 		 * image as well.
 		 */
 		bpf_jit_fixup_addresses(fp, code_base, &cgctx, addrs);

 		/* There is no need to perform the usual passes. */
 		goto skip_codegen_passes;
 	}

 	/* Code generation passes 1-2 */
 	for (pass = 1; pass < 3; pass++) {
 		/* Now build the prologue, body code & epilogue for real. */
 		cgctx.idx = 0;
 		cgctx.alt_exit_addr = 0;
 		bpf_jit_build_prologue(code_base, &cgctx);
 		if (bpf_jit_build_body(fp, code_base, &cgctx, addrs, pass)) {
 			bpf_jit_binary_free(bpf_hdr);
 			fp = org_fp;
 			goto out_addrs;
 		}
 		bpf_jit_build_epilogue(code_base, &cgctx);

 		if (bpf_jit_enable > 1)
 			pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass,
 				proglen - (cgctx.idx * 4), cgctx.seen);
 	}

 skip_codegen_passes:
 	if (bpf_jit_enable > 1)
 		/*
 		 * Note that we output the base address of the code_base
 		 * rather than image, since opcodes are in code_base.
 		 */
 		bpf_jit_dump(flen, proglen, pass, code_base);

 #ifdef CONFIG_PPC64_ELF_ABI_V1
 	/* Function descriptor nastiness: Address + TOC */
 	((u64 *)image)[0] = (u64)code_base;
 	((u64 *)image)[1] = local_paca->kernel_toc;
 #endif

 	fp->bpf_func = (void *)image;
 	fp->jited = 1;
 	fp->jited_len = proglen + FUNCTION_DESCR_SIZE;

 	bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + bpf_hdr->size);
 	if (!fp->is_func || extra_pass) {
 		bpf_jit_binary_lock_ro(bpf_hdr);
 		bpf_prog_fill_jited_linfo(fp, addrs);
 out_addrs:
 		kfree(addrs);
 		kfree(jit_data);
 		fp->aux->jit_data = NULL;
 	} else {
 		jit_data->addrs = addrs;
 		jit_data->ctx = cgctx;
 		jit_data->proglen = proglen;
 		jit_data->image = image;
 		jit_data->header = bpf_hdr;
 	}

 out:
 	if (bpf_blinded)
 		bpf_jit_prog_release_other(fp, fp == org_fp ? tmp_fp : org_fp);

 	return fp;
 }

 /*
  * The caller should check for (BPF_MODE(code) == BPF_PROBE_MEM) before calling
  * this function, as this only applies to BPF_PROBE_MEM, for now.
  */
 int bpf_add_extable_entry(struct bpf_prog *fp, u32 *image, int pass, struct codegen_context *ctx,
 			  int insn_idx, int jmp_off, int dst_reg)
 {
 	off_t offset;
 	unsigned long pc;
 	struct exception_table_entry *ex;
 	u32 *fixup;

 	/* Populate extable entries only in the last pass */
 	if (pass != 2)
 		return 0;

 	if (!fp->aux->extable ||
 	    WARN_ON_ONCE(ctx->exentry_idx >= fp->aux->num_exentries))
 		return -EINVAL;

 	pc = (unsigned long)&image[insn_idx];

 	fixup = (void *)fp->aux->extable -
 		(fp->aux->num_exentries * BPF_FIXUP_LEN * 4) +
 		(ctx->exentry_idx * BPF_FIXUP_LEN * 4);

 	fixup[0] = PPC_RAW_LI(dst_reg, 0);
 	if (IS_ENABLED(CONFIG_PPC32))
 		fixup[1] = PPC_RAW_LI(dst_reg - 1, 0); /* clear higher 32-bit register too */

 	fixup[BPF_FIXUP_LEN - 1] =
 		PPC_RAW_BRANCH((long)(pc + jmp_off) - (long)&fixup[BPF_FIXUP_LEN - 1]);

 	ex = &fp->aux->extable[ctx->exentry_idx];

 	offset = pc - (long)&ex->insn;
 	if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN))
 		return -ERANGE;
 	ex->insn = offset;

 	offset = (long)fixup - (long)&ex->fixup;
 	if (WARN_ON_ONCE(offset >= 0 || offset < INT_MIN))
 		return -ERANGE;
 	ex->fixup = offset;

 	ctx->exentry_idx++;
 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* eBPF JIT compiler
	*
	* Copyright 2016 Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
	* IBM Corporation
	*
	* Based on the powerpc classic BPF JIT compiler by Matt Evans
	*/
	#include <linux/moduleloader.h>
	#include <asm/cacheflush.h>
	#include <asm/asm-compat.h>
	#include <linux/netdevice.h>
	#include <linux/filter.h>
	#include <linux/if_vlan.h>
	#include <asm/kprobes.h>
	#include <linux/bpf.h>

	#include "bpf_jit.h"

	static void bpf_jit_fill_ill_insns(void *area, unsigned int size)
	{
	memset32(area, BREAKPOINT_INSTRUCTION, size / 4);
	}

	/* Fix updated addresses (for subprog calls, ldimm64, et al) during extra pass */
	static int bpf_jit_fixup_addresses(struct bpf_prog fp, u32 image,
	struct codegen_context ctx, u32 addrs)
	{
	const struct bpf_insn *insn = fp->insnsi;
	bool func_addr_fixed;
	u64 func_addr;
	u32 tmp_idx;
	int i, j, ret;

	for (i = 0; i < fp->len; i++) {
	/*
	* During the extra pass, only the branch target addresses for
	* the subprog calls need to be fixed. All other instructions
	* can left untouched.
	*
	* The JITed image length does not change because we already
	* ensure that the JITed instruction sequence for these calls
	* are of fixed length by padding them with NOPs.
	*/
	if (insn[i].code == (BPF_JMP \| BPF_CALL) &&
	insn[i].src_reg == BPF_PSEUDO_CALL) {
	ret = bpf_jit_get_func_addr(fp, &insn[i], true,
	&func_addr,
	&func_addr_fixed);
	if (ret < 0)
	return ret;

	/*
	* Save ctx->idx as this would currently point to the
	* end of the JITed image and set it to the offset of
	* the instruction sequence corresponding to the
	* subprog call temporarily.
	*/
	tmp_idx = ctx->idx;
	ctx->idx = addrs[i] / 4;
	ret = bpf_jit_emit_func_call_rel(image, ctx, func_addr);
	if (ret)
	return ret;

	/*
	* Restore ctx->idx here. This is safe as the length
	* of the JITed sequence remains unchanged.
	*/
	ctx->idx = tmp_idx;
	} else if (insn[i].code == (BPF_LD \| BPF_IMM \| BPF_DW)) {
	tmp_idx = ctx->idx;
	ctx->idx = addrs[i] / 4;
	#ifdef CONFIG_PPC32
	PPC_LI32(bpf_to_ppc(insn[i].dst_reg) - 1, (u32)insn[i + 1].imm);
	PPC_LI32(bpf_to_ppc(insn[i].dst_reg), (u32)insn[i].imm);
	for (j = ctx->idx - addrs[i] / 4; j < 4; j++)
	EMIT(PPC_RAW_NOP());
	#else
	func_addr = ((u64)(u32)insn[i].imm) \| (((u64)(u32)insn[i + 1].imm) << 32);
	PPC_LI64(bpf_to_ppc(insn[i].dst_reg), func_addr);
	/* overwrite rest with nops */
	for (j = ctx->idx - addrs[i] / 4; j < 5; j++)
	EMIT(PPC_RAW_NOP());
	#endif
	ctx->idx = tmp_idx;
	i++;
	}
	}

	return 0;
	}

	int bpf_jit_emit_exit_insn(u32 image, struct codegen_context ctx, int tmp_reg, long exit_addr)
	{
	if (!exit_addr \|\| is_offset_in_branch_range(exit_addr - (ctx->idx * 4))) {
	PPC_JMP(exit_addr);
	} else if (ctx->alt_exit_addr) {
	if (WARN_ON(!is_offset_in_branch_range((long)ctx->alt_exit_addr - (ctx->idx * 4))))
	return -1;
	PPC_JMP(ctx->alt_exit_addr);
	} else {
	ctx->alt_exit_addr = ctx->idx * 4;
	bpf_jit_build_epilogue(image, ctx);
	}

	return 0;
	}

	struct powerpc64_jit_data {
	struct bpf_binary_header *header;
	u32 *addrs;
	u8 *image;
	u32 proglen;
	struct codegen_context ctx;
	};

	bool bpf_jit_needs_zext(void)
	{
	return true;
	}

	struct bpf_prog bpf_int_jit_compile(struct bpf_prog fp)
	{
	u32 proglen;
	u32 alloclen;
	u8 *image = NULL;
	u32 *code_base;
	u32 *addrs;
	struct powerpc64_jit_data *jit_data;
	struct codegen_context cgctx;
	int pass;
	int flen;
	struct bpf_binary_header *bpf_hdr;
	struct bpf_prog *org_fp = fp;
	struct bpf_prog *tmp_fp;
	bool bpf_blinded = false;
	bool extra_pass = false;
	u32 extable_len;
	u32 fixup_len;

	if (!fp->jit_requested)
	return org_fp;

	tmp_fp = bpf_jit_blind_constants(org_fp);
	if (IS_ERR(tmp_fp))
	return org_fp;

	if (tmp_fp != org_fp) {
	bpf_blinded = true;
	fp = tmp_fp;
	}

	jit_data = fp->aux->jit_data;
	if (!jit_data) {
	jit_data = kzalloc(sizeof(*jit_data), GFP_KERNEL);
	if (!jit_data) {
	fp = org_fp;
	goto out;
	}
	fp->aux->jit_data = jit_data;
	}

	flen = fp->len;
	addrs = jit_data->addrs;
	if (addrs) {
	cgctx = jit_data->ctx;
	image = jit_data->image;
	bpf_hdr = jit_data->header;
	proglen = jit_data->proglen;
	extra_pass = true;
	goto skip_init_ctx;
	}

	addrs = kcalloc(flen + 1, sizeof(*addrs), GFP_KERNEL);
	if (addrs == NULL) {
	fp = org_fp;
	goto out_addrs;
	}

	memset(&cgctx, 0, sizeof(struct codegen_context));
	bpf_jit_init_reg_mapping(&cgctx);

	/* Make sure that the stack is quadword aligned. */
	cgctx.stack_size = round_up(fp->aux->stack_depth, 16);

	/* Scouting faux-generate pass 0 */
	if (bpf_jit_build_body(fp, 0, &cgctx, addrs, 0)) {
	/* We hit something illegal or unsupported. */
	fp = org_fp;
	goto out_addrs;
	}

	/*
	* If we have seen a tail call, we need a second pass.
	* This is because bpf_jit_emit_common_epilogue() is called
	* from bpf_jit_emit_tail_call() with a not yet stable ctx->seen.
	* We also need a second pass if we ended up with too large
	* a program so as to ensure BPF_EXIT branches are in range.
	*/
	if (cgctx.seen & SEEN_TAILCALL \|\| !is_offset_in_branch_range((long)cgctx.idx * 4)) {
	cgctx.idx = 0;
	if (bpf_jit_build_body(fp, 0, &cgctx, addrs, 0)) {
	fp = org_fp;
	goto out_addrs;
	}
	}

	bpf_jit_realloc_regs(&cgctx);
	/*
	* Pretend to build prologue, given the features we've seen. This will
	* update ctgtx.idx as it pretends to output instructions, then we can
	* calculate total size from idx.
	*/
	bpf_jit_build_prologue(0, &cgctx);
	addrs[fp->len] = cgctx.idx * 4;
	bpf_jit_build_epilogue(0, &cgctx);

	fixup_len = fp->aux->num_exentries * BPF_FIXUP_LEN * 4;
	extable_len = fp->aux->num_exentries * sizeof(struct exception_table_entry);

	proglen = cgctx.idx * 4;
	alloclen = proglen + FUNCTION_DESCR_SIZE + fixup_len + extable_len;

	bpf_hdr = bpf_jit_binary_alloc(alloclen, &image, 4, bpf_jit_fill_ill_insns);
	if (!bpf_hdr) {
	fp = org_fp;
	goto out_addrs;
	}

	if (extable_len)
	fp->aux->extable = (void *)image + FUNCTION_DESCR_SIZE + proglen + fixup_len;

	skip_init_ctx:
	code_base = (u32 *)(image + FUNCTION_DESCR_SIZE);

	if (extra_pass) {
	/*
	* Do not touch the prologue and epilogue as they will remain
	* unchanged. Only fix the branch target address for subprog
	* calls in the body, and ldimm64 instructions.
	*
	* This does not change the offsets and lengths of the subprog
	* call instruction sequences and hence, the size of the JITed
	* image as well.
	*/
	bpf_jit_fixup_addresses(fp, code_base, &cgctx, addrs);

	/* There is no need to perform the usual passes. */
	goto skip_codegen_passes;
	}

	/* Code generation passes 1-2 */
	for (pass = 1; pass < 3; pass++) {
	/* Now build the prologue, body code & epilogue for real. */
	cgctx.idx = 0;
	cgctx.alt_exit_addr = 0;
	bpf_jit_build_prologue(code_base, &cgctx);
	if (bpf_jit_build_body(fp, code_base, &cgctx, addrs, pass)) {
	bpf_jit_binary_free(bpf_hdr);
	fp = org_fp;
	goto out_addrs;
	}
	bpf_jit_build_epilogue(code_base, &cgctx);

	if (bpf_jit_enable > 1)
	pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass,
	proglen - (cgctx.idx * 4), cgctx.seen);
	}

	skip_codegen_passes:
	if (bpf_jit_enable > 1)
	/*
	* Note that we output the base address of the code_base
	* rather than image, since opcodes are in code_base.
	*/
	bpf_jit_dump(flen, proglen, pass, code_base);

	#ifdef CONFIG_PPC64_ELF_ABI_V1
	/* Function descriptor nastiness: Address + TOC */
	((u64 *)image)[0] = (u64)code_base;
	((u64 *)image)[1] = local_paca->kernel_toc;
	#endif

	fp->bpf_func = (void *)image;
	fp->jited = 1;
	fp->jited_len = proglen + FUNCTION_DESCR_SIZE;

	bpf_flush_icache(bpf_hdr, (u8 *)bpf_hdr + bpf_hdr->size);
	if (!fp->is_func \|\| extra_pass) {
	bpf_jit_binary_lock_ro(bpf_hdr);
	bpf_prog_fill_jited_linfo(fp, addrs);
	out_addrs:
	kfree(addrs);
	kfree(jit_data);
	fp->aux->jit_data = NULL;
	} else {
	jit_data->addrs = addrs;
	jit_data->ctx = cgctx;
	jit_data->proglen = proglen;
	jit_data->image = image;
	jit_data->header = bpf_hdr;
	}

	out:
	if (bpf_blinded)
	bpf_jit_prog_release_other(fp, fp == org_fp ? tmp_fp : org_fp);

	return fp;
	}

	/*
	* The caller should check for (BPF_MODE(code) == BPF_PROBE_MEM) before calling
	* this function, as this only applies to BPF_PROBE_MEM, for now.
	*/
	int bpf_add_extable_entry(struct bpf_prog fp, u32 image, int pass, struct codegen_context *ctx,
	int insn_idx, int jmp_off, int dst_reg)
	{
	off_t offset;
	unsigned long pc;
	struct exception_table_entry *ex;
	u32 *fixup;

	/* Populate extable entries only in the last pass */
	if (pass != 2)
	return 0;

	if (!fp->aux->extable \|\|
	WARN_ON_ONCE(ctx->exentry_idx >= fp->aux->num_exentries))
	return -EINVAL;

	pc = (unsigned long)&image[insn_idx];

	fixup = (void *)fp->aux->extable -
	(fp->aux->num_exentries * BPF_FIXUP_LEN * 4) +
	(ctx->exentry_idx * BPF_FIXUP_LEN * 4);

	fixup[0] = PPC_RAW_LI(dst_reg, 0);
	if (IS_ENABLED(CONFIG_PPC32))
	fixup[1] = PPC_RAW_LI(dst_reg - 1, 0); /* clear higher 32-bit register too */

	fixup[BPF_FIXUP_LEN - 1] =
	PPC_RAW_BRANCH((long)(pc + jmp_off) - (long)&fixup[BPF_FIXUP_LEN - 1]);

	ex = &fp->aux->extable[ctx->exentry_idx];

	offset = pc - (long)&ex->insn;
	if (WARN_ON_ONCE(offset >= 0 \|\| offset < INT_MIN))
	return -ERANGE;
	ex->insn = offset;

	offset = (long)fixup - (long)&ex->fixup;
	if (WARN_ON_ONCE(offset >= 0 \|\| offset < INT_MIN))
	return -ERANGE;
	ex->fixup = offset;

	ctx->exentry_idx++;
	return 0;
	}