Aarch64 has instructions to generate reasonably complicated 32 or 64 bit masks from only 13 bits of information. aarch64_insn_gen_logical_immediate() has to created the immediate encoding by spotting the patterns in the 32 or 64 bit immediate.
Despite attempts to validate or model this code, or use it as-is outside the kernel tree, bugs still exist.
Add a self test module that tests this code in place against a golden set of values.
Signed-off-by: James Morse james.morse@arm.com --- arch/arm64/Kconfig.debug | 3 + arch/arm64/Makefile | 2 + arch/arm64/lib/Makefile | 2 + arch/arm64/lib/insn.c | 3 + arch/arm64/lib/test_insn.c | 90 ++++++++++++++++++++++ tools/testing/selftests/arm64/Makefile | 2 +- tools/testing/selftests/arm64/lib/Makefile | 6 ++ tools/testing/selftests/arm64/lib/config | 1 + tools/testing/selftests/arm64/lib/insn.sh | 5 ++ 9 files changed, 113 insertions(+), 1 deletion(-) create mode 100644 arch/arm64/lib/test_insn.c create mode 100644 tools/testing/selftests/arm64/lib/Makefile create mode 100644 tools/testing/selftests/arm64/lib/config create mode 100755 tools/testing/selftests/arm64/lib/insn.sh
diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug index 265c4461031f..10df6056db3e 100644 --- a/arch/arm64/Kconfig.debug +++ b/arch/arm64/Kconfig.debug @@ -20,4 +20,7 @@ config ARM64_RELOC_TEST depends on m tristate "Relocation testing module"
+config TEST_INSN + tristate "Test functions located in the aarch64 instruction encoder at runtime" + source "drivers/hwtracing/coresight/Kconfig" diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 0bd590605416..4930a2b077b8 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -176,7 +176,9 @@ vdso_install:
archprepare: $(Q)$(MAKE) $(build)=arch/arm64/tools kapi +#ifdef CONFIG_TEST_INSN $(Q)$(MAKE) $(build)=arch/arm64/tools tests +#endif ifeq ($(CONFIG_ARM64_ERRATUM_843419),y) ifneq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y) @echo "warning: ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum" >&2 diff --git a/arch/arm64/lib/Makefile b/arch/arm64/lib/Makefile index 29490be2546b..d180945ecc22 100644 --- a/arch/arm64/lib/Makefile +++ b/arch/arm64/lib/Makefile @@ -22,3 +22,5 @@ obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o obj-$(CONFIG_ARM64_MTE) += mte.o
obj-$(CONFIG_KASAN_SW_TAGS) += kasan_sw_tags.o + +obj-$(CONFIG_TEST_INSN) += test_insn.o diff --git a/arch/arm64/lib/insn.c b/arch/arm64/lib/insn.c index fccfe363e567..8888e407032f 100644 --- a/arch/arm64/lib/insn.c +++ b/arch/arm64/lib/insn.c @@ -193,6 +193,7 @@ u64 aarch64_insn_decode_immediate(enum aarch64_insn_imm_type type, u32 insn)
return (insn >> shift) & mask; } +EXPORT_SYMBOL_GPL(aarch64_insn_decode_immediate);
u32 __kprobes aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type, u32 insn, u64 imm) @@ -256,6 +257,7 @@ u32 aarch64_insn_decode_register(enum aarch64_insn_register_type type,
return (insn >> shift) & GENMASK(4, 0); } +EXPORT_SYMBOL_GPL(aarch64_insn_decode_register);
static u32 aarch64_insn_encode_register(enum aarch64_insn_register_type type, u32 insn, @@ -1424,6 +1426,7 @@ u32 aarch64_insn_gen_logical_immediate(enum aarch64_insn_logic_type type, insn = aarch64_insn_encode_register(AARCH64_INSN_REGTYPE_RN, insn, Rn); return aarch64_encode_immediate(imm, variant, insn); } +EXPORT_SYMBOL_GPL(aarch64_insn_gen_logical_immediate);
u32 aarch64_insn_gen_extr(enum aarch64_insn_variant variant, enum aarch64_insn_register Rm, diff --git a/arch/arm64/lib/test_insn.c b/arch/arm64/lib/test_insn.c new file mode 100644 index 000000000000..41466f61c6c0 --- /dev/null +++ b/arch/arm64/lib/test_insn.c @@ -0,0 +1,90 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Test cases for the aarch64 insn encoder. + * + * Copyright (C) 2021 ARM Limited. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/printk.h> + +#include <asm/debug-monitors.h> +#include <asm/insn.h> + +#include "../../../tools/testing/selftests/kselftest_module.h" + +struct bitmask_test_case { + /* input */ + u64 imm; + + /* expected output */ + u64 n, immr, imms; +}; +struct bitmask_test_case aarch64_logic_imm_test[] = { +#include <asm/test_logic_imm_generated.h> +}; + +KSTM_MODULE_GLOBALS(); + +static void __init test_logic_imm(void) +{ + int i; + u8 rd, rn; + u32 insn; + + for (i = 0; i < ARRAY_SIZE(aarch64_logic_imm_test); i++) { + total_tests++; + + rd = i % 30; + rn = (i + 1) % 30; + + insn = aarch64_insn_gen_logical_immediate(AARCH64_INSN_LOGIC_AND, + AARCH64_INSN_VARIANT_64BIT, + rn, rd, aarch64_logic_imm_test[i].imm); + + if (!aarch64_insn_is_and_imm(insn) || + rd != aarch64_insn_decode_register(AARCH64_INSN_REGTYPE_RD, insn) || + rn != aarch64_insn_decode_register(AARCH64_INSN_REGTYPE_RN, insn) || + aarch64_logic_imm_test[i].imms != aarch64_insn_decode_immediate(AARCH64_INSN_IMM_S, insn) || + aarch64_logic_imm_test[i].immr != aarch64_insn_decode_immediate(AARCH64_INSN_IMM_R, insn) || + aarch64_logic_imm_test[i].n != aarch64_insn_decode_immediate(AARCH64_INSN_IMM_N, insn)) { + failed_tests++; + pr_warn_once("[%s:%u] Failed to encode immediate 0x%llx (got insn 0x%x))\n", + __FILE__, __LINE__, aarch64_logic_imm_test[i].imm, insn); + continue; + } + } +} + +static void __init do_test_bad_logic_imm(u64 imm, enum aarch64_insn_variant var) +{ + u32 insn; + + total_tests++; + insn = aarch64_insn_gen_logical_immediate(AARCH64_INSN_LOGIC_AND, + var, 0, 0, imm); + if (insn != AARCH64_BREAK_FAULT) + failed_tests++; +} + +static void __init test_bad_logic_imm(void) +{ + do_test_bad_logic_imm(0, AARCH64_INSN_VARIANT_64BIT); + do_test_bad_logic_imm(0x1234, AARCH64_INSN_VARIANT_64BIT); + do_test_bad_logic_imm(0xffffffffffffffff, AARCH64_INSN_VARIANT_64BIT); + do_test_bad_logic_imm((1ULL<<32), AARCH64_INSN_VARIANT_32BIT); +} + +static void __init selftest(void) +{ + test_logic_imm(); + test_bad_logic_imm(); +} + +KSTM_MODULE_LOADERS(test_insn); +MODULE_AUTHOR("James Morse james.morse@arm.com"); +MODULE_LICENSE("GPL"); diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile index 1e8d9a8f59df..2c59e7d40524 100644 --- a/tools/testing/selftests/arm64/Makefile +++ b/tools/testing/selftests/arm64/Makefile @@ -4,7 +4,7 @@ ARCH ?= $(shell uname -m 2>/dev/null || echo not)
ifneq (,$(filter $(ARCH),aarch64 arm64)) -ARM64_SUBTARGETS ?= tags signal pauth fp mte bti abi +ARM64_SUBTARGETS ?= tags signal pauth fp mte bti abi lib else ARM64_SUBTARGETS := endif diff --git a/tools/testing/selftests/arm64/lib/Makefile b/tools/testing/selftests/arm64/lib/Makefile new file mode 100644 index 000000000000..5ed92a5135ce --- /dev/null +++ b/tools/testing/selftests/arm64/lib/Makefile @@ -0,0 +1,6 @@ +# Copyright (C) 2022 ARM Limited +# Makefile for arm64/lib/ function selftests + +TEST_PROGS := insn.sh + +include ../../lib.mk diff --git a/tools/testing/selftests/arm64/lib/config b/tools/testing/selftests/arm64/lib/config new file mode 100644 index 000000000000..cb982478782b --- /dev/null +++ b/tools/testing/selftests/arm64/lib/config @@ -0,0 +1 @@ +CONFIG_TEST_INSN=m diff --git a/tools/testing/selftests/arm64/lib/insn.sh b/tools/testing/selftests/arm64/lib/insn.sh new file mode 100755 index 000000000000..3d893b1a0069 --- /dev/null +++ b/tools/testing/selftests/arm64/lib/insn.sh @@ -0,0 +1,5 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# Tests the aarch64 instruction generation infrastructure using test_insn +# kernel module. +$(dirname $0)/../../kselftest/module.sh "insn" test_insn