linux-user: Emulate /proc/cpuinfo on aarch64 and arm

Add emulation for /proc/cpuinfo for arm architecture.
The output below mimics output as seen on debian porterboxes.

aarch64 output example:

processor       : 0
model name      : ARMv8 Processor rev 0 (v8l)
BogoMIPS        : 100.00
Features        : swp half thumb fast_mult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae aes pmull sha1 sha2 crc32
CPU implementer : 0x41
CPU architecture: 8
CPU variant     : 0x1
CPU part        : 0xd07
CPU revision    : 0

arm 32-bit output example:

processor	: 0
model name	: ARMv7 Processor rev 5 (armv7l)
BogoMIPS	: 100.00
Features	: swp half thumb fast_mult vfp edsp thumbee neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae
CPU implementer	: 0x41
CPU architecture: 7
CPU variant	: 0x0f
CPU part	: 0xc07
CPU revision	: 5

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230803214450.647040-3-deller@gmx.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 101 insertions, 1 deletions

diff --git a/linux-user/arm/target_proc.h b/linux-user/arm/target_proc.h
index 43fe29ca72..ac75af9ca6 100644
--- a/linux-user/arm/target_proc.h
+++ b/linux-user/arm/target_proc.h
@@ -1 +1,101 @@
-/* No target-specific /proc support */
+/*
+ * Arm specific proc functions for linux-user
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#ifndef ARM_TARGET_PROC_H
+#define ARM_TARGET_PROC_H
+
+static int open_cpuinfo(CPUArchState *cpu_env, int fd)
+{
+    ARMCPU *cpu = env_archcpu(cpu_env);
+    int arch, midr_rev, midr_part, midr_var, midr_impl;
+    target_ulong elf_hwcap = get_elf_hwcap();
+    target_ulong elf_hwcap2 = get_elf_hwcap2();
+    const char *elf_name;
+    int num_cpus, len_part, len_var;
+
+#if TARGET_BIG_ENDIAN
+# define END_SUFFIX "b"
+#else
+# define END_SUFFIX "l"
+#endif
+
+    arch = 8;
+    elf_name = "v8" END_SUFFIX;
+    midr_rev = FIELD_EX32(cpu->midr, MIDR_EL1, REVISION);
+    midr_part = FIELD_EX32(cpu->midr, MIDR_EL1, PARTNUM);
+    midr_var = FIELD_EX32(cpu->midr, MIDR_EL1, VARIANT);
+    midr_impl = FIELD_EX32(cpu->midr, MIDR_EL1, IMPLEMENTER);
+    len_part = 3;
+    len_var = 1;
+
+#ifndef TARGET_AARCH64
+    /* For simplicity, treat ARMv8 as an arm64 kernel with CONFIG_COMPAT. */
+    if (!arm_feature(&cpu->env, ARM_FEATURE_V8)) {
+        if (arm_feature(&cpu->env, ARM_FEATURE_V7)) {
+            arch = 7;
+            midr_var = (cpu->midr >> 16) & 0x7f;
+            len_var = 2;
+            if (arm_feature(&cpu->env, ARM_FEATURE_M)) {
+                elf_name = "armv7m" END_SUFFIX;
+            } else {
+                elf_name = "armv7" END_SUFFIX;
+            }
+        } else {
+            midr_part = cpu->midr >> 4;
+            len_part = 7;
+            if (arm_feature(&cpu->env, ARM_FEATURE_V6)) {
+                arch = 6;
+                elf_name = "armv6" END_SUFFIX;
+            } else if (arm_feature(&cpu->env, ARM_FEATURE_V5)) {
+                arch = 5;
+                elf_name = "armv5t" END_SUFFIX;
+            } else {
+                arch = 4;
+                elf_name = "armv4" END_SUFFIX;
+            }
+        }
+    }
+#endif
+
+#undef END_SUFFIX
+
+    num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+    for (int i = 0; i < num_cpus; i++) {
+        dprintf(fd,
+                "processor\t: %d\n"
+                "model name\t: ARMv%d Processor rev %d (%s)\n"
+                "BogoMIPS\t: 100.00\n"
+                "Features\t:",
+                i, arch, midr_rev, elf_name);
+
+        for (target_ulong j = elf_hwcap; j ; j &= j - 1) {
+            dprintf(fd, " %s", elf_hwcap_str(ctz64(j)));
+        }
+        for (target_ulong j = elf_hwcap2; j ; j &= j - 1) {
+            dprintf(fd, " %s", elf_hwcap2_str(ctz64(j)));
+        }
+
+        dprintf(fd, "\n"
+                "CPU implementer\t: 0x%02x\n"
+                "CPU architecture: %d\n"
+                "CPU variant\t: 0x%0*x\n",
+                midr_impl, arch, len_var, midr_var);
+        if (arch >= 7) {
+            dprintf(fd, "CPU part\t: 0x%0*x\n", len_part, midr_part);
+        }
+        dprintf(fd, "CPU revision\t: %d\n\n", midr_rev);
+    }
+
+    if (arch < 8) {
+        dprintf(fd, "Hardware\t: QEMU v%s %s\n", QEMU_VERSION,
+                cpu->dtb_compatible ? : "");
+        dprintf(fd, "Revision\t: 0000\n");
+        dprintf(fd, "Serial\t\t: 0000000000000000\n");
+    }
+    return 0;
+}
+#define HAVE_ARCH_PROC_CPUINFO
+
+#endif /* ARM_TARGET_PROC_H */