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-rw-r--r--hw/riscv/boot.c53
-rw-r--r--hw/riscv/sifive_u.c28
-rw-r--r--hw/riscv/spike.c7
-rw-r--r--hw/riscv/virt.c7
-rw-r--r--include/hw/riscv/boot.h4
5 files changed, 66 insertions, 33 deletions
diff --git a/hw/riscv/boot.c b/hw/riscv/boot.c
index 3df802380a..c62f545f15 100644
--- a/hw/riscv/boot.c
+++ b/hw/riscv/boot.c
@@ -159,45 +159,68 @@ hwaddr riscv_load_initrd(const char *filename, uint64_t mem_size,
     return *start + size;
 }
 
+uint32_t riscv_load_fdt(hwaddr dram_base, uint64_t mem_size, void *fdt)
+{
+    uint32_t temp, fdt_addr;
+    hwaddr dram_end = dram_base + mem_size;
+    int fdtsize = fdt_totalsize(fdt);
+
+    if (fdtsize <= 0) {
+        error_report("invalid device-tree");
+        exit(1);
+    }
+
+    /*
+     * We should put fdt as far as possible to avoid kernel/initrd overwriting
+     * its content. But it should be addressable by 32 bit system as well.
+     * Thus, put it at an aligned address that less than fdt size from end of
+     * dram or 4GB whichever is lesser.
+     */
+    temp = MIN(dram_end, 4096 * MiB);
+    fdt_addr = QEMU_ALIGN_DOWN(temp - fdtsize, 2 * MiB);
+
+    fdt_pack(fdt);
+    /* copy in the device tree */
+    qemu_fdt_dumpdtb(fdt, fdtsize);
+
+    rom_add_blob_fixed_as("fdt", fdt, fdtsize, fdt_addr,
+                          &address_space_memory);
+
+    return fdt_addr;
+}
+
 void riscv_setup_rom_reset_vec(hwaddr start_addr, hwaddr rom_base,
-                               hwaddr rom_size, void *fdt)
+                               hwaddr rom_size,
+                               uint32_t fdt_load_addr, void *fdt)
 {
     int i;
 
     /* reset vector */
-    uint32_t reset_vec[8] = {
+    uint32_t reset_vec[10] = {
         0x00000297,                  /* 1:  auipc  t0, %pcrel_hi(dtb) */
-        0x02028593,                  /*     addi   a1, t0, %pcrel_lo(1b) */
         0xf1402573,                  /*     csrr   a0, mhartid  */
 #if defined(TARGET_RISCV32)
+        0x0202a583,                  /*     lw     a1, 32(t0) */
         0x0182a283,                  /*     lw     t0, 24(t0) */
 #elif defined(TARGET_RISCV64)
+        0x0202b583,                  /*     ld     a1, 32(t0) */
         0x0182b283,                  /*     ld     t0, 24(t0) */
 #endif
         0x00028067,                  /*     jr     t0 */
         0x00000000,
         start_addr,                  /* start: .dword */
         0x00000000,
+        fdt_load_addr,               /* fdt_laddr: .dword */
+        0x00000000,
                                      /* dtb: */
     };
 
     /* copy in the reset vector in little_endian byte order */
-    for (i = 0; i < sizeof(reset_vec) >> 2; i++) {
+    for (i = 0; i < ARRAY_SIZE(reset_vec); i++) {
         reset_vec[i] = cpu_to_le32(reset_vec[i]);
     }
     rom_add_blob_fixed_as("mrom.reset", reset_vec, sizeof(reset_vec),
                           rom_base, &address_space_memory);
 
-    /* copy in the device tree */
-    if (fdt_pack(fdt) || fdt_totalsize(fdt) >
-        rom_size - sizeof(reset_vec)) {
-        error_report("not enough space to store device-tree");
-        exit(1);
-    }
-    qemu_fdt_dumpdtb(fdt, fdt_totalsize(fdt));
-    rom_add_blob_fixed_as("mrom.fdt", fdt, fdt_totalsize(fdt),
-                           rom_base + sizeof(reset_vec),
-                           &address_space_memory);
-
     return;
 }
diff --git a/hw/riscv/sifive_u.c b/hw/riscv/sifive_u.c
index 0695c93d2c..39923209f4 100644
--- a/hw/riscv/sifive_u.c
+++ b/hw/riscv/sifive_u.c
@@ -379,6 +379,7 @@ static void sifive_u_machine_init(MachineState *machine)
     MemoryRegion *flash0 = g_new(MemoryRegion, 1);
     target_ulong start_addr = memmap[SIFIVE_U_DRAM].base;
     int i;
+    uint32_t fdt_load_addr;
 
     /* Initialize SoC */
     object_initialize_child(OBJECT(machine), "soc", &s->soc, TYPE_RISCV_U_SOC);
@@ -450,40 +451,37 @@ static void sifive_u_machine_init(MachineState *machine)
         }
     }
 
+    /* Compute the fdt load address in dram */
+    fdt_load_addr = riscv_load_fdt(memmap[SIFIVE_U_DRAM].base,
+                                   machine->ram_size, s->fdt);
+
     /* reset vector */
-    uint32_t reset_vec[8] = {
+    uint32_t reset_vec[11] = {
         s->msel,                       /* MSEL pin state */
         0x00000297,                    /* 1:  auipc  t0, %pcrel_hi(dtb) */
-        0x01c28593,                    /*     addi   a1, t0, %pcrel_lo(1b) */
         0xf1402573,                    /*     csrr   a0, mhartid  */
 #if defined(TARGET_RISCV32)
+        0x0202a583,                    /*     lw     a1, 32(t0) */
         0x0182a283,                    /*     lw     t0, 24(t0) */
 #elif defined(TARGET_RISCV64)
-        0x0182e283,                    /*     lwu    t0, 24(t0) */
+        0x0202b583,                    /*     ld     a1, 32(t0) */
+        0x0182b283,                    /*     ld     t0, 24(t0) */
 #endif
         0x00028067,                    /*     jr     t0 */
         0x00000000,
         start_addr,                    /* start: .dword */
+        0x00000000,
+        fdt_load_addr,                 /* fdt_laddr: .dword */
+        0x00000000,
                                        /* dtb: */
     };
 
     /* copy in the reset vector in little_endian byte order */
-    for (i = 0; i < sizeof(reset_vec) >> 2; i++) {
+    for (i = 0; i < ARRAY_SIZE(reset_vec); i++) {
         reset_vec[i] = cpu_to_le32(reset_vec[i]);
     }
     rom_add_blob_fixed_as("mrom.reset", reset_vec, sizeof(reset_vec),
                           memmap[SIFIVE_U_MROM].base, &address_space_memory);
-
-    /* copy in the device tree */
-    if (fdt_pack(s->fdt) || fdt_totalsize(s->fdt) >
-            memmap[SIFIVE_U_MROM].size - sizeof(reset_vec)) {
-        error_report("not enough space to store device-tree");
-        exit(1);
-    }
-    qemu_fdt_dumpdtb(s->fdt, fdt_totalsize(s->fdt));
-    rom_add_blob_fixed_as("mrom.fdt", s->fdt, fdt_totalsize(s->fdt),
-                          memmap[SIFIVE_U_MROM].base + sizeof(reset_vec),
-                          &address_space_memory);
 }
 
 static bool sifive_u_machine_get_start_in_flash(Object *obj, Error **errp)
diff --git a/hw/riscv/spike.c b/hw/riscv/spike.c
index a8a0588824..13fa0455e3 100644
--- a/hw/riscv/spike.c
+++ b/hw/riscv/spike.c
@@ -163,6 +163,7 @@ static void spike_board_init(MachineState *machine)
     MemoryRegion *main_mem = g_new(MemoryRegion, 1);
     MemoryRegion *mask_rom = g_new(MemoryRegion, 1);
     unsigned int smp_cpus = machine->smp.cpus;
+    uint32_t fdt_load_addr;
 
     /* Initialize SOC */
     object_initialize_child(OBJECT(machine), "soc", &s->soc,
@@ -208,9 +209,13 @@ static void spike_board_init(MachineState *machine)
         }
     }
 
+    /* Compute the fdt load address in dram */
+    fdt_load_addr = riscv_load_fdt(memmap[SPIKE_DRAM].base,
+                                   machine->ram_size, s->fdt);
     /* load the reset vector */
     riscv_setup_rom_reset_vec(memmap[SPIKE_DRAM].base, memmap[SPIKE_MROM].base,
-                              memmap[SPIKE_MROM].size, s->fdt);
+                              memmap[SPIKE_MROM].size,
+                              fdt_load_addr, s->fdt);
 
     /* initialize HTIF using symbols found in load_kernel */
     htif_mm_init(system_memory, mask_rom, &s->soc.harts[0].env, serial_hd(0));
diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
index 3463cf54aa..9d87319f70 100644
--- a/hw/riscv/virt.c
+++ b/hw/riscv/virt.c
@@ -478,6 +478,7 @@ static void virt_machine_init(MachineState *machine)
     char *plic_hart_config;
     size_t plic_hart_config_len;
     target_ulong start_addr = memmap[VIRT_DRAM].base;
+    uint32_t fdt_load_addr;
     int i;
     unsigned int smp_cpus = machine->smp.cpus;
 
@@ -532,9 +533,13 @@ static void virt_machine_init(MachineState *machine)
         start_addr = virt_memmap[VIRT_FLASH].base;
     }
 
+    /* Compute the fdt load address in dram */
+    fdt_load_addr = riscv_load_fdt(memmap[VIRT_DRAM].base,
+                                   machine->ram_size, s->fdt);
     /* load the reset vector */
     riscv_setup_rom_reset_vec(start_addr, virt_memmap[VIRT_MROM].base,
-                              virt_memmap[VIRT_MROM].size, s->fdt);
+                              virt_memmap[VIRT_MROM].size,
+                              fdt_load_addr, s->fdt);
 
     /* create PLIC hart topology configuration string */
     plic_hart_config_len = (strlen(VIRT_PLIC_HART_CONFIG) + 1) * smp_cpus;
diff --git a/include/hw/riscv/boot.h b/include/hw/riscv/boot.h
index 3e9759c89a..35b6ddf710 100644
--- a/include/hw/riscv/boot.h
+++ b/include/hw/riscv/boot.h
@@ -35,7 +35,9 @@ target_ulong riscv_load_kernel(const char *kernel_filename,
                                symbol_fn_t sym_cb);
 hwaddr riscv_load_initrd(const char *filename, uint64_t mem_size,
                          uint64_t kernel_entry, hwaddr *start);
+uint32_t riscv_load_fdt(hwaddr dram_start, uint64_t dram_size, void *fdt);
 void riscv_setup_rom_reset_vec(hwaddr saddr, hwaddr rom_base,
-                               hwaddr rom_size, void *fdt);
+                               hwaddr rom_size,
+                               uint32_t fdt_load_addr, void *fdt);
 
 #endif /* RISCV_BOOT_H */