hw/riscv: Load the kernel after the firmware

Instead of loading the kernel at a hardcoded start address, let's load
the kernel at the next aligned address after the end of the firmware.

This should have no impact for current users of OpenSBI, but will
allow loading a noMMU kernel at the start of memory.

Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
Tested-by: Bin Meng <bin.meng@windriver.com>
Message-id: 46c00c4f15b42feb792090e3d74359e180a6d954.1602634524.git.alistair.francis@wdc.com

hw/riscv/boot.c

@@ -33,10 +33,8 @@
 #include <libfdt.h>
 
 #if defined(TARGET_RISCV32)
-# define KERNEL_BOOT_ADDRESS 0x80400000
 #define fw_dynamic_info_data(__val)     cpu_to_le32(__val)
 #else
-# define KERNEL_BOOT_ADDRESS 0x80200000
 #define fw_dynamic_info_data(__val)     cpu_to_le64(__val)
 #endif
 
@@ -49,6 +47,15 @@ bool riscv_is_32_bit(MachineState *machine)
     }
 }
 
+target_ulong riscv_calc_kernel_start_addr(MachineState *machine,
+                                          target_ulong firmware_end_addr) {
+    if (riscv_is_32_bit(machine)) {
+        return QEMU_ALIGN_UP(firmware_end_addr, 4 * MiB);
+    } else {
+        return QEMU_ALIGN_UP(firmware_end_addr, 2 * MiB);
+    }
+}
+
 target_ulong riscv_find_and_load_firmware(MachineState *machine,
                                           const char *default_machine_firmware,
                                           hwaddr firmware_load_addr,
@@ -123,7 +130,9 @@ target_ulong riscv_load_firmware(const char *firmware_filename,
     exit(1);
 }
 
-target_ulong riscv_load_kernel(const char *kernel_filename, symbol_fn_t sym_cb)
+target_ulong riscv_load_kernel(const char *kernel_filename,
+                               target_ulong kernel_start_addr,
+                               symbol_fn_t sym_cb)
 {
     uint64_t kernel_entry;
 
@@ -138,9 +147,9 @@ target_ulong riscv_load_kernel(const char *kernel_filename, symbol_fn_t sym_cb)
         return kernel_entry;
     }
 
-    if (load_image_targphys_as(kernel_filename, KERNEL_BOOT_ADDRESS,
+    if (load_image_targphys_as(kernel_filename, kernel_start_addr,
                                ram_size, NULL) > 0) {
-        return KERNEL_BOOT_ADDRESS;
+        return kernel_start_addr;
     }
 
     error_report("could not load kernel '%s'", kernel_filename);

hw/riscv/opentitan.c

@@ -75,7 +75,8 @@ static void opentitan_board_init(MachineState *machine)
     }
 
     if (machine->kernel_filename) {
-        riscv_load_kernel(machine->kernel_filename, NULL);
+        riscv_load_kernel(machine->kernel_filename,
+                          memmap[IBEX_DEV_RAM].base, NULL);
     }
 }
 

hw/riscv/sifive_e.c

@@ -114,7 +114,8 @@ static void sifive_e_machine_init(MachineState *machine)
                           memmap[SIFIVE_E_DEV_MROM].base, &address_space_memory);
 
     if (machine->kernel_filename) {
-        riscv_load_kernel(machine->kernel_filename, NULL);
+        riscv_load_kernel(machine->kernel_filename,
+                          memmap[SIFIVE_E_DEV_DTIM].base, NULL);
     }
 }
 

hw/riscv/sifive_u.c

@@ -415,6 +415,7 @@ static void sifive_u_machine_init(MachineState *machine)
     MemoryRegion *main_mem = g_new(MemoryRegion, 1);
     MemoryRegion *flash0 = g_new(MemoryRegion, 1);
     target_ulong start_addr = memmap[SIFIVE_U_DEV_DRAM].base;
+    target_ulong firmware_end_addr, kernel_start_addr;
     uint32_t start_addr_hi32 = 0x00000000;
     int i;
     uint32_t fdt_load_addr;
@@ -474,10 +475,15 @@ static void sifive_u_machine_init(MachineState *machine)
         break;
     }
 
-    riscv_find_and_load_firmware(machine, BIOS_FILENAME, start_addr, NULL);
+    firmware_end_addr = riscv_find_and_load_firmware(machine, BIOS_FILENAME,
+                                                     start_addr, NULL);
 
     if (machine->kernel_filename) {
-        kernel_entry = riscv_load_kernel(machine->kernel_filename, NULL);
+        kernel_start_addr = riscv_calc_kernel_start_addr(machine,
+                                                         firmware_end_addr);
+
+        kernel_entry = riscv_load_kernel(machine->kernel_filename,
+                                         kernel_start_addr, NULL);
 
         if (machine->initrd_filename) {
             hwaddr start;

hw/riscv/spike.c

@@ -195,6 +195,7 @@ static void spike_board_init(MachineState *machine)
     MemoryRegion *system_memory = get_system_memory();
     MemoryRegion *main_mem = g_new(MemoryRegion, 1);
     MemoryRegion *mask_rom = g_new(MemoryRegion, 1);
+    target_ulong firmware_end_addr, kernel_start_addr;
     uint32_t fdt_load_addr;
     uint64_t kernel_entry;
     char *soc_name;
@@ -261,12 +262,16 @@ static void spike_board_init(MachineState *machine)
     memory_region_add_subregion(system_memory, memmap[SPIKE_MROM].base,
                                 mask_rom);
 
-    riscv_find_and_load_firmware(machine, BIOS_FILENAME,
+    firmware_end_addr = riscv_find_and_load_firmware(machine, BIOS_FILENAME,
                                                      memmap[SPIKE_DRAM].base,
                                                      htif_symbol_callback);
 
     if (machine->kernel_filename) {
+        kernel_start_addr = riscv_calc_kernel_start_addr(machine,
+                                                         firmware_end_addr);
+
         kernel_entry = riscv_load_kernel(machine->kernel_filename,
+                                         kernel_start_addr,
                                          htif_symbol_callback);
 
         if (machine->initrd_filename) {

hw/riscv/virt.c

@@ -493,6 +493,7 @@ static void virt_machine_init(MachineState *machine)
     char *plic_hart_config, *soc_name;
     size_t plic_hart_config_len;
     target_ulong start_addr = memmap[VIRT_DRAM].base;
+    target_ulong firmware_end_addr, kernel_start_addr;
     uint32_t fdt_load_addr;
     uint64_t kernel_entry;
     DeviceState *mmio_plic, *virtio_plic, *pcie_plic;
@@ -602,11 +603,15 @@ static void virt_machine_init(MachineState *machine)
     memory_region_add_subregion(system_memory, memmap[VIRT_MROM].base,
                                 mask_rom);
 
-    riscv_find_and_load_firmware(machine, BIOS_FILENAME,
+    firmware_end_addr = riscv_find_and_load_firmware(machine, BIOS_FILENAME,
-                                 memmap[VIRT_DRAM].base, NULL);
+                                                     start_addr, NULL);
 
     if (machine->kernel_filename) {
-        kernel_entry = riscv_load_kernel(machine->kernel_filename, NULL);
+        kernel_start_addr = riscv_calc_kernel_start_addr(machine,
+                                                         firmware_end_addr);
+
+        kernel_entry = riscv_load_kernel(machine->kernel_filename,
+                                         kernel_start_addr, NULL);
 
         if (machine->initrd_filename) {
             hwaddr start;

include/hw/riscv/boot.h

@@ -25,6 +25,8 @@
 
 bool riscv_is_32_bit(MachineState *machine);
 
+target_ulong riscv_calc_kernel_start_addr(MachineState *machine,
+                                          target_ulong firmware_end_addr);
 target_ulong riscv_find_and_load_firmware(MachineState *machine,
                                           const char *default_machine_firmware,
                                           hwaddr firmware_load_addr,
@@ -34,6 +36,7 @@ target_ulong riscv_load_firmware(const char *firmware_filename,
                                  hwaddr firmware_load_addr,
                                  symbol_fn_t sym_cb);
 target_ulong riscv_load_kernel(const char *kernel_filename,
+                               target_ulong firmware_end_addr,
                                symbol_fn_t sym_cb);
 hwaddr riscv_load_initrd(const char *filename, uint64_t mem_size,
                          uint64_t kernel_entry, hwaddr *start);