Parse some ACPI structures

kernel/include/kernel/acpi/rsdp.h

@@ -0,0 +1,36 @@
+#ifndef ACPI_RSDP_H
+#define ACPI_RSDP_H
+
+#include <stdint.h>
+
+typedef struct __attribute__ ((packed)) {
+	char	 signature[8];
+	uint8_t	 checksum;
+	char	 oemid[6];
+	uint8_t	 revision;
+	uint32_t rsdt_address;
+} RSDP_t;
+
+typedef struct __attribute__ ((packed)) {
+	char	 signature[8];
+	uint8_t	 checksum;
+	char	 oemid[6];
+	uint8_t	 revision;
+	uint32_t rsdt_address;
+	uint32_t length;
+	uint64_t xsdt_address;
+	uint8_t	 extended_checksum;
+	uint8_t	 reserved[3];
+} XSDP_t;
+
+void* init_rsdp (uintptr_t rsdp_base_ptr, uint64_t hhdm_offset);
+
+bool is_init (void);
+bool is_rsdp (void);
+bool is_xsdp (void);
+
+uint8_t get_rsdp_revision ();
+RSDP_t* get_rsdp ();
+XSDP_t* get_xsdp ();
+
+#endif

kernel/include/kernel/acpi/rsdt.h

@@ -0,0 +1,13 @@
+#ifndef ACPI_RSDT_H
+#define ACPI_RSDT_H
+
+#include <kernel/acpi/sdt_header.h>
+
+typedef struct __attribute__ ((packed)) {
+	SDT_header_t header;
+	uint32_t	 other_sdt_ptrs[];
+} RSDT_t;
+
+void init_rsdt (RSDP_t* rsdp_base_ptr);
+
+#endif

kernel/include/kernel/acpi/sdt_header.h

@@ -0,0 +1,18 @@
+#ifndef ACPI_SDT_HEADER_H
+#define ACPI_SDT_HEADER_H
+
+#include <stdint.h>
+
+typedef struct __attribute__ ((packed)) {
+	char	 signature[4];
+	uint32_t length;
+	uint8_t	 revision;
+	uint8_t	 checksum;
+	char	 oemid[6];
+	char	 oemTableId[8];
+	uint32_t oemRevision;
+	uint32_t creatorId;
+	uint32_t creatorRevision;
+} SDT_header_t;
+
+#endif

kernel/include/kernel/memmgt.h

@@ -6,7 +6,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#define PAGE_SIZE 4096ull
+#define PAGE_SIZE		   4096ull
+#define ALIGN_PAGE_DOWN(x) ((x) & ~(PAGE_SIZE - 1))
 
 typedef struct {
 	uint64_t present : 1;			 // Page present in memory
@@ -91,7 +92,8 @@ uint64_t read_cr3 (void);
 void	 write_cr3 (uint64_t new_value);
 
 vaddr_t get_vaddr_t_from_ptr (void* ptr);
-void*	get_vaddr_from_frame (uint64_t phys_address);
+void*	get_vaddr_from_frame (uint64_t phys_frame);
+void*	get_vaddr_from_phys_addr (uint64_t phys_address);
 void*	vaddr_t_to_ptr (vaddr_t* virtual_addr);
 
 void* alloc_vpages (size_t req_count, bool user);

kernel/src/kernel/acpi/rsdp.c

@@ -0,0 +1,60 @@
+#include <kclib/string.h>
+#include <kernel/acpi/rsdp.h>
+#include <kernel/memmgt.h>
+
+static bool is_init_flag = false;
+
+static RSDP_t* rsdp_ptr = nullptr;
+static XSDP_t* xsdp_ptr = nullptr;
+static uint8_t rsdp_ver = 0;
+
+static void* init_and_return (void* arg) {
+	is_init_flag = true;
+	return arg;
+}
+
+inline bool is_init (void) { return is_init_flag; }
+inline bool is_rsdp (void) { return is_init () ? (rsdp_ptr != nullptr) : false; }
+inline bool is_xsdp (void) { return is_init () ? (xsdp_ptr != nullptr) : false; }
+
+uint8_t get_rsdp_revision (void) { return rsdp_ver; }
+RSDP_t* get_rsdp (void) { return rsdp_ptr; }
+XSDP_t* get_xsdp (void) { return xsdp_ptr; }
+
+void* init_rsdp (uintptr_t rsdp_base_ptr, uint64_t hhdm_offset) {
+	if (rsdp_base_ptr == 0) return nullptr;
+
+	// check if address is physical ; if it is, we will probably have to allocate memory
+	if (rsdp_base_ptr < hhdm_offset) {
+		paddr_t rsdp_base_frame = (paddr_t)ALIGN_PAGE_DOWN (rsdp_base_ptr);
+		vaddr_t rsdp_vaddr_start =
+			get_vaddr_t_from_ptr ((void*)ALIGN_PAGE_DOWN (rsdp_base_ptr + hhdm_offset));
+		vaddr_t rsdp_vaddr_end = get_vaddr_t_from_ptr (
+			(void*)ALIGN_PAGE_DOWN (rsdp_base_ptr + hhdm_offset + sizeof (XSDP_t)));
+
+		alloc_all_vpages_in_range (rsdp_vaddr_start, rsdp_vaddr_end, rsdp_base_frame);
+		rsdp_base_ptr += hhdm_offset;
+	}
+
+	RSDP_t* tmp_rsdp_ptr = (RSDP_t*)rsdp_base_ptr;
+	XSDP_t* tmp_xsdp_ptr = (XSDP_t*)rsdp_base_ptr;
+
+	// validate the RSDP & set revision
+	uint8_t rsdp_checksum = 0;
+	for (uint64_t i = 0; i < sizeof (RSDP_t); i++)
+		rsdp_checksum += ((uint8_t*)tmp_rsdp_ptr)[i];
+	if (rsdp_checksum != 0) return nullptr;
+	if (kmemcmp (tmp_rsdp_ptr->signature, "RSD PTR ", 8) != 0) return nullptr;
+	rsdp_ver = tmp_rsdp_ptr->revision;
+
+	// if we are on rev 1, set rsdp_ptr and leave
+	if (rsdp_ver == 0) return init_and_return (rsdp_ptr = tmp_rsdp_ptr);
+
+	// validate the XSDP
+	uint8_t xsdp_checksum = 0;
+	for (uint64_t j = 0; j < sizeof (XSDP_t); j++)
+		xsdp_checksum += ((uint8_t*)tmp_xsdp_ptr)[j];
+	if (xsdp_checksum != 0) return nullptr;
+
+	return init_and_return (xsdp_ptr = tmp_xsdp_ptr);
+}

kernel/src/kernel/entry.c

@@ -1,5 +1,6 @@
 #include <kclib/stdio.h>
 #include <kclib/string.h>
+#include <kernel/acpi/rsdp.h>
 #include <kernel/console.h>
 #include <kernel/elf.h>
 #include <kernel/fs/chardev.h>
@@ -30,9 +31,11 @@ extern volatile struct limine_boot_time_request		  boottime_req;
 extern volatile struct limine_memmap_request		  memmap_req;
 extern volatile struct limine_module_request		  mod_req;
 extern volatile struct limine_hhdm_request			  hhdm_req;
+extern volatile struct limine_rsdp_request			  rsdp_req;
 
 struct limine_framebuffer* framebuffer = nullptr;
 struct limine_file*		   initramfs = nullptr;
+uintptr_t				   rsdp = 0;
 uint64_t				   hhdm_base = 0;
 
 // Declaration of kernel entry points
@@ -104,6 +107,7 @@ static void print_info (void) {
 __attribute__ ((noreturn)) void _start_stage2 (void) {
 	init_graphics (framebuffer);
 	init_console (framebuffer->width, framebuffer->height, 40, 40, 1, 1, 2);
+	rsdp = (uintptr_t)init_rsdp (rsdp, hhdm_base);
 
 	for (int i = 0; i < 3; i++) // open stdin, stdout and stderr
 		do_syscall (SYSCALL_SYS_OPEN, (uint64_t)"/dev/tty1", 0, 0);
@@ -118,6 +122,9 @@ __attribute__ ((noreturn)) void _start_stage2 (void) {
 
 	kprintf ("[Stage 2] Trying to load the ELF.\n");
 
+	kserial_printf ("RSDP Address: %llx\n", rsdp);
+	kserial_printf ("ACPI Revision: %u\n", get_rsdp_revision ());
+
 	uint64_t fork_result = do_syscall (SYSCALL_SYS_FORK, 0, 0, 0);
 
 	if (fork_result == 0) {
@@ -158,10 +165,14 @@ static void get_limine_requests (void) {
 	// REQUIRED: modules (for initramfs)
 	if (mod_req.response == nullptr || mod_req.response->module_count < 1) hcf ();
 
+	// REQUIRED: RSDP for ACPI
+	if (rsdp_req.response == nullptr) hcf ();
+
 	// set the values received from limine
 	framebuffer = framebuffer_request.response->framebuffers[0];
 	hhdm_base = hhdm_req.response->offset;
 	initramfs = mod_req.response->modules[0];
+	rsdp = (uintptr_t)rsdp_req.response->address;
 }
 
 /*!

kernel/src/kernel/limine_requests.c

@@ -24,6 +24,10 @@ __attribute__ ((used,
 				section (".limine_requests"))) volatile struct limine_module_request mod_req = {
 	.id = LIMINE_MODULE_REQUEST, .revision = 0};
 
+__attribute__ ((used,
+				section (".limine_requests"))) volatile struct limine_rsdp_request rsdp_req = {
+	.id = LIMINE_RSDP_REQUEST, .revision = 0};
+
 __attribute__ ((used,
 				section (".limine_requests_start"))) static volatile LIMINE_REQUESTS_START_MARKER;
 

kernel/src/kernel/memmgt.c

@@ -84,6 +84,15 @@ inline void* get_vaddr_from_frame (uint64_t phys_frame) {
 	return (void*)((phys_frame << 12) + hhdm_offset);
 }
 
+/*!
+ * Access a physical pointer as vaddr pointer with HHDM mapping
+ * @param phys_address the physical pointer
+ * @return pointer to virtual memory using HHDM mapping
+ */
+void* get_vaddr_from_phys_addr (uint64_t phys_address) {
+	return (void*)(phys_address + hhdm_offset);
+}
+
 /*!
  * Set a bit in the memory bitmap
  * @param page_idx page index

user/hello/Makefile

@@ -103,4 +103,4 @@ clean:
 
 .PHONY: format
 format:
-	find -type f \( -name '*.c' -o -name '*.h' \) ! -name 'limine.h' -exec clang-format -i {} +
+	find . -type f \( -name '*.c' -o -name '*.h' \) ! -name 'limine.h' -exec clang-format -i {} +