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Commit 69887b8c authored by Zi Shen Lim's avatar Zi Shen Lim Committed by Runmin Wang
Browse files

arm64: insn: remove BUG_ON from codegen 

During code generation, we used to BUG_ON unknown/unsupported encoding
or invalid parameters.

Instead, now we report these as errors and simply return the
instruction AARCH64_BREAK_FAULT. Users of these codegen helpers should
check for and handle this failure condition as appropriate.

Otherwise, unhandled codegen failure will result in trapping at
run-time due to AARCH64_BREAK_FAULT, which is arguably better than a
BUG_ON.

Change-Id: I35f8d8960c0a3f6cecf0690e8f93fce339ed8838
Git-commit: c94ae4f7c5ec6b6fddde1c08809d5e32a963d7f3
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: default avatarZi Shen Lim <zlim.lnx@gmail.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarRunmin Wang <runminw@codeaurora.org>
parent 0d5578df

arch/arm64/kernel/insn.c

+112 −53
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
 * Copyright (C) 2013 Huawei Ltd.

 * Author: Jiang Liu <liuj97@gmail.com>

 *

 * Copyright (C) 2014 Zi Shen Lim <zlim.lnx@gmail.com>

 * Copyright (C) 2014-2016 Zi Shen Lim <zlim.lnx@gmail.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as
@@ -364,6 +364,9 @@ u32 __kprobes aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type, 
	u32 immlo, immhi, mask;

	int shift;



	if (insn == AARCH64_BREAK_FAULT)

		return AARCH64_BREAK_FAULT;



	switch (type) {

	case AARCH64_INSN_IMM_ADR:

		shift = 0;
@@ -378,7 +381,7 @@ u32 __kprobes aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type, 
		if (aarch64_get_imm_shift_mask(type, &mask, &shift) < 0) {

			pr_err("aarch64_insn_encode_immediate: unknown immediate encoding %d\n",

			       type);

			return 0;

			return AARCH64_BREAK_FAULT;

		}

	}
@@ -395,9 +398,12 @@ static u32 aarch64_insn_encode_register(enum aarch64_insn_register_type type, 
{

	int shift;



	if (insn == AARCH64_BREAK_FAULT)

		return AARCH64_BREAK_FAULT;



	if (reg < AARCH64_INSN_REG_0 || reg > AARCH64_INSN_REG_SP) {

		pr_err("%s: unknown register encoding %d\n", __func__, reg);

		return 0;

		return AARCH64_BREAK_FAULT;

	}



	switch (type) {
@@ -418,7 +424,7 @@ static u32 aarch64_insn_encode_register(enum aarch64_insn_register_type type, 
	default:

		pr_err("%s: unknown register type encoding %d\n", __func__,

		       type);

		return 0;

		return AARCH64_BREAK_FAULT;

	}



	insn &= ~(GENMASK(4, 0) << shift);
@@ -447,7 +453,7 @@ static u32 aarch64_insn_encode_ldst_size(enum aarch64_insn_size_type type, 
		break;

	default:

		pr_err("%s: unknown size encoding %d\n", __func__, type);

		return 0;

		return AARCH64_BREAK_FAULT;

	}



	insn &= ~GENMASK(31, 30);
@@ -461,14 +467,17 @@ static inline long branch_imm_common(unsigned long pc, unsigned long addr, 
{

	long offset;



	/*

	 * PC: A 64-bit Program Counter holding the address of the current

	 * instruction. A64 instructions must be word-aligned.

	 */

	BUG_ON((pc & 0x3) || (addr & 0x3));

	if ((pc & 0x3) || (addr & 0x3)) {

		pr_err("%s: A64 instructions must be word aligned\n", __func__);

		return range;

	}



	offset = ((long)addr - (long)pc);

	BUG_ON(offset < -range || offset >= range);



	if (offset < -range || offset >= range) {

		pr_err("%s: offset out of range\n", __func__);

		return range;

	}



	return offset;

}
@@ -485,6 +494,8 @@ u32 __kprobes aarch64_insn_gen_branch_imm(unsigned long pc, unsigned long addr, 
	 * texts are within +/-128M.

	 */

	offset = branch_imm_common(pc, addr, SZ_128M);

	if (offset >= SZ_128M)

		return AARCH64_BREAK_FAULT;



	switch (type) {

	case AARCH64_INSN_BRANCH_LINK:
@@ -494,7 +505,7 @@ u32 __kprobes aarch64_insn_gen_branch_imm(unsigned long pc, unsigned long addr, 
		insn = aarch64_insn_get_b_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown branch encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}
@@ -511,6 +522,8 @@ u32 aarch64_insn_gen_comp_branch_imm(unsigned long pc, unsigned long addr, 
	long offset;



	offset = branch_imm_common(pc, addr, SZ_1M);

	if (offset >= SZ_1M)

		return AARCH64_BREAK_FAULT;



	switch (type) {

	case AARCH64_INSN_BRANCH_COMP_ZERO:
@@ -520,7 +533,7 @@ u32 aarch64_insn_gen_comp_branch_imm(unsigned long pc, unsigned long addr, 
		insn = aarch64_insn_get_cbnz_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown branch encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}
@@ -531,7 +544,7 @@ u32 aarch64_insn_gen_comp_branch_imm(unsigned long pc, unsigned long addr, 
		insn |= AARCH64_INSN_SF_BIT;

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown variant encoding %d\n", __func__, variant);

		return AARCH64_BREAK_FAULT;

	}
@@ -551,7 +564,10 @@ u32 aarch64_insn_gen_cond_branch_imm(unsigned long pc, unsigned long addr, 


	insn = aarch64_insn_get_bcond_value();



	BUG_ON(cond < AARCH64_INSN_COND_EQ || cond > AARCH64_INSN_COND_AL);

	if (cond < AARCH64_INSN_COND_EQ || cond > AARCH64_INSN_COND_AL) {

		pr_err("%s: unknown condition encoding %d\n", __func__, cond);

		return AARCH64_BREAK_FAULT;

	}

	insn |= cond;



	return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_19, insn,
@@ -584,7 +600,7 @@ u32 aarch64_insn_gen_branch_reg(enum aarch64_insn_register reg, 
		insn = aarch64_insn_get_ret_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown branch encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}
@@ -607,7 +623,7 @@ u32 aarch64_insn_gen_load_store_reg(enum aarch64_insn_register reg, 
		insn = aarch64_insn_get_str_reg_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown load/store encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}
@@ -646,26 +662,30 @@ u32 aarch64_insn_gen_load_store_pair(enum aarch64_insn_register reg1, 
		insn = aarch64_insn_get_stp_post_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown load/store encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}



	switch (variant) {

	case AARCH64_INSN_VARIANT_32BIT:

		/* offset must be multiples of 4 in the range [-256, 252] */

		BUG_ON(offset & 0x3);

		BUG_ON(offset < -256 || offset > 252);

		if ((offset & 0x3) || (offset < -256) || (offset > 252)) {

			pr_err("%s: offset must be multiples of 4 in the range of [-256, 252] %d\n",

			       __func__, offset);

			return AARCH64_BREAK_FAULT;

		}

		shift = 2;

		break;

	case AARCH64_INSN_VARIANT_64BIT:

		/* offset must be multiples of 8 in the range [-512, 504] */

		BUG_ON(offset & 0x7);

		BUG_ON(offset < -512 || offset > 504);

		if ((offset & 0x7) || (offset < -512) || (offset > 504)) {

			pr_err("%s: offset must be multiples of 8 in the range of [-512, 504] %d\n",

			       __func__, offset);

			return AARCH64_BREAK_FAULT;

		}

		shift = 3;

		insn |= AARCH64_INSN_SF_BIT;

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown variant encoding %d\n", __func__, variant);

		return AARCH64_BREAK_FAULT;

	}
@@ -703,7 +723,7 @@ u32 aarch64_insn_gen_add_sub_imm(enum aarch64_insn_register dst, 
		insn = aarch64_insn_get_subs_imm_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown add/sub encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}
@@ -714,11 +734,14 @@ u32 aarch64_insn_gen_add_sub_imm(enum aarch64_insn_register dst, 
		insn |= AARCH64_INSN_SF_BIT;

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown variant encoding %d\n", __func__, variant);

		return AARCH64_BREAK_FAULT;

	}



	BUG_ON(imm & ~(SZ_4K - 1));

	if (imm & ~(SZ_4K - 1)) {

		pr_err("%s: invalid immediate encoding %d\n", __func__, imm);

		return AARCH64_BREAK_FAULT;

	}



	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RD, insn, dst);
@@ -747,7 +770,7 @@ u32 aarch64_insn_gen_bitfield(enum aarch64_insn_register dst, 
		insn = aarch64_insn_get_sbfm_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown bitfield encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}
@@ -760,12 +783,18 @@ u32 aarch64_insn_gen_bitfield(enum aarch64_insn_register dst, 
		mask = GENMASK(5, 0);

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown variant encoding %d\n", __func__, variant);

		return AARCH64_BREAK_FAULT;

	}



	BUG_ON(immr & ~mask);

	BUG_ON(imms & ~mask);

	if (immr & ~mask) {

		pr_err("%s: invalid immr encoding %d\n", __func__, immr);

		return AARCH64_BREAK_FAULT;

	}

	if (imms & ~mask) {

		pr_err("%s: invalid imms encoding %d\n", __func__, imms);

		return AARCH64_BREAK_FAULT;

	}



	insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RD, insn, dst);
@@ -794,23 +823,33 @@ u32 aarch64_insn_gen_movewide(enum aarch64_insn_register dst, 
		insn = aarch64_insn_get_movn_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown movewide encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}



	BUG_ON(imm & ~(SZ_64K - 1));

	if (imm & ~(SZ_64K - 1)) {

		pr_err("%s: invalid immediate encoding %d\n", __func__, imm);

		return AARCH64_BREAK_FAULT;

	}



	switch (variant) {

	case AARCH64_INSN_VARIANT_32BIT:

		BUG_ON(shift != 0 && shift != 16);

		if (shift != 0 && shift != 16) {

			pr_err("%s: invalid shift encoding %d\n", __func__,

			       shift);

			return AARCH64_BREAK_FAULT;

		}

		break;

	case AARCH64_INSN_VARIANT_64BIT:

		insn |= AARCH64_INSN_SF_BIT;

		BUG_ON(shift != 0 && shift != 16 && shift != 32 &&

		       shift != 48);

		if (shift != 0 && shift != 16 && shift != 32 && shift != 48) {

			pr_err("%s: invalid shift encoding %d\n", __func__,

			       shift);

			return AARCH64_BREAK_FAULT;

		}

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown variant encoding %d\n", __func__, variant);

		return AARCH64_BREAK_FAULT;

	}
@@ -844,20 +883,28 @@ u32 aarch64_insn_gen_add_sub_shifted_reg(enum aarch64_insn_register dst, 
		insn = aarch64_insn_get_subs_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown add/sub encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}



	switch (variant) {

	case AARCH64_INSN_VARIANT_32BIT:

		BUG_ON(shift & ~(SZ_32 - 1));

		if (shift & ~(SZ_32 - 1)) {

			pr_err("%s: invalid shift encoding %d\n", __func__,

			       shift);

			return AARCH64_BREAK_FAULT;

		}

		break;

	case AARCH64_INSN_VARIANT_64BIT:

		insn |= AARCH64_INSN_SF_BIT;

		BUG_ON(shift & ~(SZ_64 - 1));

		if (shift & ~(SZ_64 - 1)) {

			pr_err("%s: invalid shift encoding %d\n", __func__,

			       shift);

			return AARCH64_BREAK_FAULT;

		}

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown variant encoding %d\n", __func__, variant);

		return AARCH64_BREAK_FAULT;

	}
@@ -886,11 +933,15 @@ u32 aarch64_insn_gen_data1(enum aarch64_insn_register dst, 
		insn = aarch64_insn_get_rev32_value();

		break;

	case AARCH64_INSN_DATA1_REVERSE_64:

		BUG_ON(variant != AARCH64_INSN_VARIANT_64BIT);

		if (variant != AARCH64_INSN_VARIANT_64BIT) {

			pr_err("%s: invalid variant for reverse64 %d\n",

			       __func__, variant);

			return AARCH64_BREAK_FAULT;

		}

		insn = aarch64_insn_get_rev64_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown data1 encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}
@@ -901,7 +952,7 @@ u32 aarch64_insn_gen_data1(enum aarch64_insn_register dst, 
		insn |= AARCH64_INSN_SF_BIT;

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown variant encoding %d\n", __func__, variant);

		return AARCH64_BREAK_FAULT;

	}
@@ -938,7 +989,7 @@ u32 aarch64_insn_gen_data2(enum aarch64_insn_register dst, 
		insn = aarch64_insn_get_rorv_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown data2 encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}
@@ -949,7 +1000,7 @@ u32 aarch64_insn_gen_data2(enum aarch64_insn_register dst, 
		insn |= AARCH64_INSN_SF_BIT;

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown variant encoding %d\n", __func__, variant);

		return AARCH64_BREAK_FAULT;

	}
@@ -977,7 +1028,7 @@ u32 aarch64_insn_gen_data3(enum aarch64_insn_register dst, 
		insn = aarch64_insn_get_msub_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown data3 encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}
@@ -988,7 +1039,7 @@ u32 aarch64_insn_gen_data3(enum aarch64_insn_register dst, 
		insn |= AARCH64_INSN_SF_BIT;

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown variant encoding %d\n", __func__, variant);

		return AARCH64_BREAK_FAULT;

	}
@@ -1038,20 +1089,28 @@ u32 aarch64_insn_gen_logical_shifted_reg(enum aarch64_insn_register dst, 
		insn = aarch64_insn_get_bics_value();

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown logical encoding %d\n", __func__, type);

		return AARCH64_BREAK_FAULT;

	}



	switch (variant) {

	case AARCH64_INSN_VARIANT_32BIT:

		BUG_ON(shift & ~(SZ_32 - 1));

		if (shift & ~(SZ_32 - 1)) {

			pr_err("%s: invalid shift encoding %d\n", __func__,

			       shift);

			return AARCH64_BREAK_FAULT;

		}

		break;

	case AARCH64_INSN_VARIANT_64BIT:

		insn |= AARCH64_INSN_SF_BIT;

		BUG_ON(shift & ~(SZ_64 - 1));

		if (shift & ~(SZ_64 - 1)) {

			pr_err("%s: invalid shift encoding %d\n", __func__,

			       shift);

			return AARCH64_BREAK_FAULT;

		}

		break;

	default:

		BUG_ON(1);

		pr_err("%s: unknown variant encoding %d\n", __func__, variant);

		return AARCH64_BREAK_FAULT;

	}