utils: Add more functions to detect CPU features

These functions will be used to skip over parts not supported by A7-A11 SoCs.

Signed-off-by: Nick Chan <towinchenmi@gmail.com>

src/cpu_regs.h

@@ -629,3 +629,13 @@
 /* Lockdown registers */
 #define SYS_IMP_APL_SPR_LOCKDOWN_EL2 sys_reg(3, 4, 15, 0, 5)
 #define SYS_IMP_APL_SPR_LOCKDOWN_EL1 sys_reg(3, 4, 15, 0, 6)
+
+/* Feature ID registers */
+#define AIDR_EL1_MUL53          BIT(0)
+#define AIDR_EL1_WKDM           BIT(1)
+#define AIDR_EL1_ARCH_RETENTION BIT(2)
+#define AIDR_EL1_AMX            BIT(4)
+#define AIDR_EL1_TSO            BIT(9)
+#define AIDR_EL1_GXF            BIT(16)
+#define AIDR_EL1_APFLG          BIT(19)
+#define AIDR_EL1_PSRV           BIT(20)

src/main.c

@@ -39,9 +39,18 @@ u32 board_id = ~0, chip_id = ~0;
 
 void get_device_info(void)
 {
+    const char *model = (const char *)adt_getprop(adt, 0, "model", NULL);
+    const char *target = (const char *)adt_getprop(adt, 0, "target-type", NULL);
+
     printf("Device info:\n");
-    printf("  Model: %s\n", (const char *)adt_getprop(adt, 0, "model", NULL));
-    printf("  Target: %s\n", (const char *)adt_getprop(adt, 0, "target-type", NULL));
+
+    if (model)
+        printf("  Model: %s\n", model);
+
+    if (target)
+        printf("  Target: %s\n", target);
+
+    is_mac = !!strstr(model, "Mac");
 
     int chosen = adt_path_offset(adt, "/chosen");
     if (chosen > 0) {

src/string.c

@@ -188,6 +188,30 @@ char *strrchr(const char *s, int c)
     return NULL;
 }
 
+char *strstr(const char *s1, const char *s2)
+{
+    const char *p1 = s1;
+    const char *p2;
+
+    while (*s1) {
+        p2 = s2;
+
+        while (*p2 && (*p1 == *p2)) {
+            ++p1;
+            ++p2;
+        }
+
+        if (!*p2) {
+            return (char *)s1;
+        }
+
+        ++s1;
+        p1 = s1;
+    }
+
+    return NULL;
+}
+
 /* Very naive, no attempt to check for errors */
 long atol(const char *s)
 {

src/utils.c

@@ -4,12 +4,15 @@
 #include <stdarg.h>
 
 #include "utils.h"
+#include "cpu_regs.h"
 #include "iodev.h"
 #include "smp.h"
 #include "types.h"
 #include "vsprintf.h"
 #include "xnuboot.h"
 
+bool is_mac = false;
+
 static char ascii(char s)
 {
     if (s < 0x20)
@@ -181,6 +184,21 @@ bool is_heap(void *addr)
     return p > top_of_kernel_data && p < top_of_ram;
 }
 
+bool supports_arch_retention(void)
+{
+    return mrs(AIDR_EL1) & AIDR_EL1_ARCH_RETENTION;
+}
+
+bool supports_gxf(void)
+{
+    return mrs(AIDR_EL1) & AIDR_EL1_GXF;
+}
+
+bool supports_pan(void)
+{
+    return (mrs(ID_AA64MMFR1_EL1) >> 20) & 0xf;
+}
+
 // TODO: update mapping?
 u64 top_of_memory_alloc(size_t size)
 {

src/utils.h

@@ -429,6 +429,7 @@ struct vector_args {
 };
 
 extern u32 board_id, chip_id;
+extern bool is_mac;
 extern bool cpufeat_actlr_el2;
 
 extern struct vector_args next_stage;
@@ -437,6 +438,9 @@ void cpu_sleep(bool deep) __attribute__((noreturn));
 void deep_wfi(void);
 
 bool is_heap(void *addr);
+bool supports_arch_retention(void);
+bool supports_gxf(void);
+bool supports_pan(void);
 u64 top_of_memory_alloc(size_t size);
 
 #endif

sysinc/string.h

@@ -18,6 +18,7 @@ size_t strlen(const char *s);
 size_t strnlen(const char *s, size_t n);
 char *strchr(const char *s, int c);
 char *strrchr(const char *s, int c);
+char *strstr(const char *s1, const char *s2);
 long atol(const char *s);
 
 static inline int tolower(int c)