Message-Id: <1597665863-564-1-git-send-email-anshuman.khandual@arm.com>
Date:   Mon, 17 Aug 2020 17:34:23 +0530
From:   Anshuman Khandual <anshuman.khandual@....com>
To:     linux-arm-kernel@...ts.infradead.org, catalin.marinas@....com,
        will@...nel.org
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        Mark Brown <broonie@...nel.org>,
        Dave Martin <Dave.Martin@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH V3] arm64/cpuinfo: Define HWCAP name arrays per their actual bit definitions

HWCAP name arrays (hwcap_str, compat_hwcap_str, compat_hwcap2_str) that are
scanned for /proc/cpuinfo are detached from their bit definitions making it
vulnerable and difficult to correlate. It is also bit problematic because
during /proc/cpuinfo dump these arrays get traversed sequentially assuming
they reflect and match actual HWCAP bit sequence, to test various features
for a given CPU. This redefines name arrays per their HWCAP bit definitions
. It also warns after detecting any feature which is not expected on arm64.

Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will@...nel.org>
Cc: Mark Brown <broonie@...nel.org>
Cc: Dave Martin <Dave.Martin@....com>
Cc: Ard Biesheuvel <ardb@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Suzuki K Poulose <suzuki.poulose@....com>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
---
This applies on 5.9-rc1

Mark, since the patch has changed I have dropped your Acked-by: tag. Are you
happy to give a new one ?

Changes in V3:

- Moved name arrays to (arch/arm64/kernel/cpuinfo.c) to prevent a build warning
- Replaced string values with NULL for all compat features not possible on arm64
- Changed compat_hwcap_str[] iteration on size as some NULL values are expected
- Warn once after detecting any feature on arm64 that is not expected

Changes in V2: (https://patchwork.kernel.org/patch/11533755/)

- Defined COMPAT_KERNEL_HWCAP[2] and updated the name arrays per Mark
- Updated the commit message as required

Changes in V1: (https://patchwork.kernel.org/patch/11532945/)

 arch/arm64/include/asm/hwcap.h |   9 +++
 arch/arm64/kernel/cpuinfo.c    | 172 ++++++++++++++++++++++-------------------
 2 files changed, 100 insertions(+), 81 deletions(-)

diff --git a/arch/arm64/include/asm/hwcap.h b/arch/arm64/include/asm/hwcap.h
index 22f73fe..6493a4c 100644
--- a/arch/arm64/include/asm/hwcap.h
+++ b/arch/arm64/include/asm/hwcap.h
@@ -8,18 +8,27 @@
 #include <uapi/asm/hwcap.h>
 #include <asm/cpufeature.h>
 
+#define COMPAT_HWCAP_SWP	(1 << 0)
 #define COMPAT_HWCAP_HALF	(1 << 1)
 #define COMPAT_HWCAP_THUMB	(1 << 2)
+#define COMPAT_HWCAP_26BIT	(1 << 3)
 #define COMPAT_HWCAP_FAST_MULT	(1 << 4)
+#define COMPAT_HWCAP_FPA	(1 << 5)
 #define COMPAT_HWCAP_VFP	(1 << 6)
 #define COMPAT_HWCAP_EDSP	(1 << 7)
+#define COMPAT_HWCAP_JAVA	(1 << 8)
+#define COMPAT_HWCAP_IWMMXT	(1 << 9)
+#define COMPAT_HWCAP_CRUNCH	(1 << 10)
+#define COMPAT_HWCAP_THUMBEE	(1 << 11)
 #define COMPAT_HWCAP_NEON	(1 << 12)
 #define COMPAT_HWCAP_VFPv3	(1 << 13)
+#define COMPAT_HWCAP_VFPV3D16	(1 << 14)
 #define COMPAT_HWCAP_TLS	(1 << 15)
 #define COMPAT_HWCAP_VFPv4	(1 << 16)
 #define COMPAT_HWCAP_IDIVA	(1 << 17)
 #define COMPAT_HWCAP_IDIVT	(1 << 18)
 #define COMPAT_HWCAP_IDIV	(COMPAT_HWCAP_IDIVA|COMPAT_HWCAP_IDIVT)
+#define COMPAT_HWCAP_VFPD32	(1 << 19)
 #define COMPAT_HWCAP_LPAE	(1 << 20)
 #define COMPAT_HWCAP_EVTSTRM	(1 << 21)
 
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 393c6fb..382cb4c 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -43,94 +43,95 @@ static const char *icache_policy_str[] = {
 unsigned long __icache_flags;
 
 static const char *const hwcap_str[] = {
-	"fp",
-	"asimd",
-	"evtstrm",
-	"aes",
-	"pmull",
-	"sha1",
-	"sha2",
-	"crc32",
-	"atomics",
-	"fphp",
-	"asimdhp",
-	"cpuid",
-	"asimdrdm",
-	"jscvt",
-	"fcma",
-	"lrcpc",
-	"dcpop",
-	"sha3",
-	"sm3",
-	"sm4",
-	"asimddp",
-	"sha512",
-	"sve",
-	"asimdfhm",
-	"dit",
-	"uscat",
-	"ilrcpc",
-	"flagm",
-	"ssbs",
-	"sb",
-	"paca",
-	"pacg",
-	"dcpodp",
-	"sve2",
-	"sveaes",
-	"svepmull",
-	"svebitperm",
-	"svesha3",
-	"svesm4",
-	"flagm2",
-	"frint",
-	"svei8mm",
-	"svef32mm",
-	"svef64mm",
-	"svebf16",
-	"i8mm",
-	"bf16",
-	"dgh",
-	"rng",
-	"bti",
+	[KERNEL_HWCAP_FP]		= "fp",
+	[KERNEL_HWCAP_ASIMD]		= "asimd",
+	[KERNEL_HWCAP_EVTSTRM]		= "evtstrm",
+	[KERNEL_HWCAP_AES]		= "aes",
+	[KERNEL_HWCAP_PMULL]		= "pmull",
+	[KERNEL_HWCAP_SHA1]		= "sha1",
+	[KERNEL_HWCAP_SHA2]		= "sha2",
+	[KERNEL_HWCAP_CRC32]		= "crc32",
+	[KERNEL_HWCAP_ATOMICS]		= "atomics",
+	[KERNEL_HWCAP_FPHP]		= "fphp",
+	[KERNEL_HWCAP_ASIMDHP]		= "asimdhp",
+	[KERNEL_HWCAP_CPUID]		= "cpuid",
+	[KERNEL_HWCAP_ASIMDRDM]		= "asimdrdm",
+	[KERNEL_HWCAP_JSCVT]		= "jscvt",
+	[KERNEL_HWCAP_FCMA]		= "fcma",
+	[KERNEL_HWCAP_LRCPC]		= "lrcpc",
+	[KERNEL_HWCAP_DCPOP]		= "dcpop",
+	[KERNEL_HWCAP_SHA3]		= "sha3",
+	[KERNEL_HWCAP_SM3]		= "sm3",
+	[KERNEL_HWCAP_SM4]		= "sm4",
+	[KERNEL_HWCAP_ASIMDDP]		= "asimddp",
+	[KERNEL_HWCAP_SHA512]		= "sha512",
+	[KERNEL_HWCAP_SVE]		= "sve",
+	[KERNEL_HWCAP_ASIMDFHM]		= "asimdfhm",
+	[KERNEL_HWCAP_DIT]		= "dit",
+	[KERNEL_HWCAP_USCAT]		= "uscat",
+	[KERNEL_HWCAP_ILRCPC]		= "ilrcpc",
+	[KERNEL_HWCAP_FLAGM]		= "flagm",
+	[KERNEL_HWCAP_SSBS]		= "ssbs",
+	[KERNEL_HWCAP_SB]		= "sb",
+	[KERNEL_HWCAP_PACA]		= "paca",
+	[KERNEL_HWCAP_PACG]		= "pacg",
+	[KERNEL_HWCAP_DCPODP]		= "dcpodp",
+	[KERNEL_HWCAP_SVE2]		= "sve2",
+	[KERNEL_HWCAP_SVEAES]		= "sveaes",
+	[KERNEL_HWCAP_SVEPMULL]		= "svepmull",
+	[KERNEL_HWCAP_SVEBITPERM]	= "svebitperm",
+	[KERNEL_HWCAP_SVESHA3]		= "svesha3",
+	[KERNEL_HWCAP_SVESM4]		= "svesm4",
+	[KERNEL_HWCAP_FLAGM2]		= "flagm2",
+	[KERNEL_HWCAP_FRINT]		= "frint",
+	[KERNEL_HWCAP_SVEI8MM]		= "svei8mm",
+	[KERNEL_HWCAP_SVEF32MM]		= "svef32mm",
+	[KERNEL_HWCAP_SVEF64MM]		= "svef64mm",
+	[KERNEL_HWCAP_SVEBF16]		= "svebf16",
+	[KERNEL_HWCAP_I8MM]		= "i8mm",
+	[KERNEL_HWCAP_BF16]		= "bf16",
+	[KERNEL_HWCAP_DGH]		= "dgh",
+	[KERNEL_HWCAP_RNG]		= "rng",
+	[KERNEL_HWCAP_BTI]		= "bti",
 	/* reserved for "mte" */
 	NULL
 };
 
 #ifdef CONFIG_COMPAT
+#define COMPAT_KERNEL_HWCAP(x)	const_ilog2(COMPAT_HWCAP_ ## x)
 static const char *const compat_hwcap_str[] = {
-	"swp",
-	"half",
-	"thumb",
-	"26bit",
-	"fastmult",
-	"fpa",
-	"vfp",
-	"edsp",
-	"java",
-	"iwmmxt",
-	"crunch",
-	"thumbee",
-	"neon",
-	"vfpv3",
-	"vfpv3d16",
-	"tls",
-	"vfpv4",
-	"idiva",
-	"idivt",
-	"vfpd32",
-	"lpae",
-	"evtstrm",
-	NULL
+	[COMPAT_KERNEL_HWCAP(SWP)]	= "swp",
+	[COMPAT_KERNEL_HWCAP(HALF)]	= "half",
+	[COMPAT_KERNEL_HWCAP(THUMB)]	= "thumb",
+	[COMPAT_KERNEL_HWCAP(26BIT)]	= NULL,	/* Not possible on arm64 */
+	[COMPAT_KERNEL_HWCAP(FAST_MULT)] = "fastmult",
+	[COMPAT_KERNEL_HWCAP(FPA)]	= NULL,	/* Not possible on arm64 */
+	[COMPAT_KERNEL_HWCAP(VFP)]	= "vfp",
+	[COMPAT_KERNEL_HWCAP(EDSP)]	= "edsp",
+	[COMPAT_KERNEL_HWCAP(JAVA)]	= NULL,	/* Not possible on arm64 */
+	[COMPAT_KERNEL_HWCAP(IWMMXT)]	= NULL,	/* Not possible on arm64 */
+	[COMPAT_KERNEL_HWCAP(CRUNCH)]	= NULL,	/* Not possible on arm64 */
+	[COMPAT_KERNEL_HWCAP(THUMBEE)]	= NULL,	/* Not possible on arm64 */
+	[COMPAT_KERNEL_HWCAP(NEON)]	= "neon",
+	[COMPAT_KERNEL_HWCAP(VFPv3)]	= "vfpv3",
+	[COMPAT_KERNEL_HWCAP(VFPV3D16)]	= NULL,	/* Not possible on arm64 */
+	[COMPAT_KERNEL_HWCAP(TLS)]	= "tls",
+	[COMPAT_KERNEL_HWCAP(VFPv4)]	= "vfpv4",
+	[COMPAT_KERNEL_HWCAP(IDIVA)]	= "idiva",
+	[COMPAT_KERNEL_HWCAP(IDIVT)]	= "idivt",
+	[COMPAT_KERNEL_HWCAP(VFPD32)]	= NULL,	/* Not possible on arm64 */
+	[COMPAT_KERNEL_HWCAP(LPAE)]	= "lpae",
+	[COMPAT_KERNEL_HWCAP(EVTSTRM)]	= "evtstrm",
 };
 
+#define COMPAT_KERNEL_HWCAP2(x)	const_ilog2(COMPAT_HWCAP2_ ## x)
 static const char *const compat_hwcap2_str[] = {
-	"aes",
-	"pmull",
-	"sha1",
-	"sha2",
-	"crc32",
-	NULL
+	[COMPAT_KERNEL_HWCAP2(AES)]	= "aes",
+	[COMPAT_KERNEL_HWCAP2(PMULL)]	= "pmull",
+	[COMPAT_KERNEL_HWCAP2(SHA1)]	= "sha1",
+	[COMPAT_KERNEL_HWCAP2(SHA2)]	= "sha2",
+	[COMPAT_KERNEL_HWCAP2(CRC32)]	= "crc32",
+	NULL,
 };
 #endif /* CONFIG_COMPAT */
 
@@ -166,9 +167,18 @@ static int c_show(struct seq_file *m, void *v)
 		seq_puts(m, "Features\t:");
 		if (compat) {
 #ifdef CONFIG_COMPAT
-			for (j = 0; compat_hwcap_str[j]; j++)
-				if (compat_elf_hwcap & (1 << j))
+			for (j = 0; j < ARRAY_SIZE(compat_hwcap_str); j++) {
+				if (compat_elf_hwcap & (1 << j)) {
+					/*
+					 * Warn once if any feature should not
+					 * have been present on arm64 platform.
+					 */
+					if (WARN_ON_ONCE(!compat_hwcap_str[j]))
+						continue;
+
 					seq_printf(m, " %s", compat_hwcap_str[j]);
+				}
+			}
 
 			for (j = 0; compat_hwcap2_str[j]; j++)
 				if (compat_elf_hwcap2 & (1 << j))
-- 
2.7.4

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