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Subject[PATCH V3] arm64/cpuinfo: Define HWCAP name arrays per their actual bit definitions
Date
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@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Dave Martin <Dave.Martin@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.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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