diff mbox series

[v2] m68k: write bootinfo as rom section and re-randomize on reboot

Message ID 20221002103707.909560-1-Jason@zx2c4.com
State New
Headers show
Series [v2] m68k: write bootinfo as rom section and re-randomize on reboot | expand

Commit Message

Jason A. Donenfeld Oct. 2, 2022, 10:37 a.m. UTC 
Rather than poking directly into RAM, add the bootinfo block as a proper
ROM, so that it's restored when rebooting the system. This way, if the
guest corrupts any of the bootinfo items, but then tries to reboot,
it'll still be restored back to normal as expected. This assumes the
bootinfo block won't exceed 1k.

Then, since the RNG seed needs to be fresh on each boot, regenerate the
RNG seed in the ROM when reseting the CPU.

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 hw/m68k/bootinfo.h | 48 +++++++++++++++++-----------------
 hw/m68k/q800.c     | 65 ++++++++++++++++++++++++++++++++--------------
 hw/m68k/virt.c     | 45 +++++++++++++++++++++-----------
 3 files changed, 99 insertions(+), 59 deletions(-)
diff mbox series

Patch

diff --git a/hw/m68k/bootinfo.h b/hw/m68k/bootinfo.h
index 897162b818..eb92937cf6 100644
--- a/hw/m68k/bootinfo.h
+++ b/hw/m68k/bootinfo.h
@@ -12,66 +12,66 @@ 
 #ifndef HW_M68K_BOOTINFO_H
 #define HW_M68K_BOOTINFO_H
 
-#define BOOTINFO0(as, base, id) \
+#define BOOTINFO0(base, id) \
     do { \
-        stw_phys(as, base, id); \
+        stw_p(base, id); \
         base += 2; \
-        stw_phys(as, base, sizeof(struct bi_record)); \
+        stw_p(base, sizeof(struct bi_record)); \
         base += 2; \
     } while (0)
 
-#define BOOTINFO1(as, base, id, value) \
+#define BOOTINFO1(base, id, value) \
     do { \
-        stw_phys(as, base, id); \
+        stw_p(base, id); \
         base += 2; \
-        stw_phys(as, base, sizeof(struct bi_record) + 4); \
+        stw_p(base, sizeof(struct bi_record) + 4); \
         base += 2; \
-        stl_phys(as, base, value); \
+        stl_p(base, value); \
         base += 4; \
     } while (0)
 
-#define BOOTINFO2(as, base, id, value1, value2) \
+#define BOOTINFO2(base, id, value1, value2) \
     do { \
-        stw_phys(as, base, id); \
+        stw_p(base, id); \
         base += 2; \
-        stw_phys(as, base, sizeof(struct bi_record) + 8); \
+        stw_p(base, sizeof(struct bi_record) + 8); \
         base += 2; \
-        stl_phys(as, base, value1); \
+        stl_p(base, value1); \
         base += 4; \
-        stl_phys(as, base, value2); \
+        stl_p(base, value2); \
         base += 4; \
     } while (0)
 
-#define BOOTINFOSTR(as, base, id, string) \
+#define BOOTINFOSTR(base, id, string) \
     do { \
         int i; \
-        stw_phys(as, base, id); \
+        stw_p(base, id); \
         base += 2; \
-        stw_phys(as, base, \
+        stw_p(base, \
                  (sizeof(struct bi_record) + strlen(string) + \
                   1 /* null termination */ + 3 /* padding */) & ~3); \
         base += 2; \
         for (i = 0; string[i]; i++) { \
-            stb_phys(as, base++, string[i]); \
+            stb_p(base++, string[i]); \
         } \
-        stb_phys(as, base++, 0); \
-        base = (base + 3) & ~3; \
+        stb_p(base++, 0); \
+        base = (void *)(((unsigned long)base + 3) & ~3); \
     } while (0)
 
-#define BOOTINFODATA(as, base, id, data, len) \
+#define BOOTINFODATA(base, id, data, len) \
     do { \
         int i; \
-        stw_phys(as, base, id); \
+        stw_p(base, id); \
         base += 2; \
-        stw_phys(as, base, \
+        stw_p(base, \
                  (sizeof(struct bi_record) + len + \
                   2 /* length field */ + 3 /* padding */) & ~3); \
         base += 2; \
-        stw_phys(as, base, len); \
+        stw_p(base, len); \
         base += 2; \
         for (i = 0; i < len; ++i) { \
-            stb_phys(as, base++, data[i]); \
+            stb_p(base++, data[i]); \
         } \
-        base = (base + 3) & ~3; \
+        base = (void *)(((unsigned long)base + 3) & ~3); \
     } while (0)
 #endif
diff --git a/hw/m68k/q800.c b/hw/m68k/q800.c
index a4590c2cb0..d94da38cde 100644
--- a/hw/m68k/q800.c
+++ b/hw/m68k/q800.c
@@ -321,11 +321,22 @@  static const TypeInfo glue_info = {
     },
 };
 
+typedef struct {
+    M68kCPU *cpu;
+    struct bi_record *rng_seed;
+} ResetInfo;
+
 static void main_cpu_reset(void *opaque)
 {
-    M68kCPU *cpu = opaque;
+    ResetInfo *reset_info = opaque;
+    M68kCPU *cpu = reset_info->cpu;
     CPUState *cs = CPU(cpu);
 
+    if (reset_info->rng_seed) {
+        qemu_guest_getrandom_nofail((void *)reset_info->rng_seed->data + 2,
+            be16_to_cpu(*(uint16_t *)reset_info->rng_seed->data));
+    }
+
     cpu_reset(cs);
     cpu->env.aregs[7] = ldl_phys(cs->as, 0);
     cpu->env.pc = ldl_phys(cs->as, 4);
@@ -386,6 +397,7 @@  static void q800_init(MachineState *machine)
     NubusBus *nubus;
     DeviceState *glue;
     DriveInfo *dinfo;
+    ResetInfo *reset_info;
     uint8_t rng_seed[32];
 
     linux_boot = (kernel_filename != NULL);
@@ -396,9 +408,12 @@  static void q800_init(MachineState *machine)
         exit(1);
     }
 
+    reset_info = g_new0(ResetInfo, 1);
+
     /* init CPUs */
     cpu = M68K_CPU(cpu_create(machine->cpu_type));
-    qemu_register_reset(main_cpu_reset, cpu);
+    reset_info->cpu = cpu;
+    qemu_register_reset(main_cpu_reset, reset_info);
 
     /* RAM */
     memory_region_add_subregion(get_system_memory(), 0, machine->ram);
@@ -598,6 +613,8 @@  static void q800_init(MachineState *machine)
     cs = CPU(cpu);
     if (linux_boot) {
         uint64_t high;
+        void *param_blob = g_malloc(1024), *param_ptr, *param_rng_seed;
+
         kernel_size = load_elf(kernel_filename, NULL, NULL, NULL,
                                &elf_entry, NULL, &high, NULL, 1,
                                EM_68K, 0, 0);
@@ -607,23 +624,24 @@  static void q800_init(MachineState *machine)
         }
         stl_phys(cs->as, 4, elf_entry); /* reset initial PC */
         parameters_base = (high + 1) & ~1;
-
-        BOOTINFO1(cs->as, parameters_base, BI_MACHTYPE, MACH_MAC);
-        BOOTINFO1(cs->as, parameters_base, BI_FPUTYPE, FPU_68040);
-        BOOTINFO1(cs->as, parameters_base, BI_MMUTYPE, MMU_68040);
-        BOOTINFO1(cs->as, parameters_base, BI_CPUTYPE, CPU_68040);
-        BOOTINFO1(cs->as, parameters_base, BI_MAC_CPUID, CPUB_68040);
-        BOOTINFO1(cs->as, parameters_base, BI_MAC_MODEL, MAC_MODEL_Q800);
-        BOOTINFO1(cs->as, parameters_base,
+        param_ptr = param_blob;
+
+        BOOTINFO1(param_ptr, BI_MACHTYPE, MACH_MAC);
+        BOOTINFO1(param_ptr, BI_FPUTYPE, FPU_68040);
+        BOOTINFO1(param_ptr, BI_MMUTYPE, MMU_68040);
+        BOOTINFO1(param_ptr, BI_CPUTYPE, CPU_68040);
+        BOOTINFO1(param_ptr, BI_MAC_CPUID, CPUB_68040);
+        BOOTINFO1(param_ptr, BI_MAC_MODEL, MAC_MODEL_Q800);
+        BOOTINFO1(param_ptr,
                   BI_MAC_MEMSIZE, ram_size >> 20); /* in MB */
-        BOOTINFO2(cs->as, parameters_base, BI_MEMCHUNK, 0, ram_size);
-        BOOTINFO1(cs->as, parameters_base, BI_MAC_VADDR,
+        BOOTINFO2(param_ptr, BI_MEMCHUNK, 0, ram_size);
+        BOOTINFO1(param_ptr, BI_MAC_VADDR,
                   VIDEO_BASE + macfb_mode->offset);
-        BOOTINFO1(cs->as, parameters_base, BI_MAC_VDEPTH, graphic_depth);
-        BOOTINFO1(cs->as, parameters_base, BI_MAC_VDIM,
+        BOOTINFO1(param_ptr, BI_MAC_VDEPTH, graphic_depth);
+        BOOTINFO1(param_ptr, BI_MAC_VDIM,
                   (graphic_height << 16) | graphic_width);
-        BOOTINFO1(cs->as, parameters_base, BI_MAC_VROW, macfb_mode->stride);
-        BOOTINFO1(cs->as, parameters_base, BI_MAC_SCCBASE, SCC_BASE);
+        BOOTINFO1(param_ptr, BI_MAC_VROW, macfb_mode->stride);
+        BOOTINFO1(param_ptr, BI_MAC_SCCBASE, SCC_BASE);
 
         rom = g_malloc(sizeof(*rom));
         memory_region_init_ram_ptr(rom, NULL, "m68k_fake_mac.rom",
@@ -632,13 +650,14 @@  static void q800_init(MachineState *machine)
         memory_region_add_subregion(get_system_memory(), MACROM_ADDR, rom);
 
         if (kernel_cmdline) {
-            BOOTINFOSTR(cs->as, parameters_base, BI_COMMAND_LINE,
+            BOOTINFOSTR(param_ptr, BI_COMMAND_LINE,
                         kernel_cmdline);
         }
 
         /* Pass seed to RNG. */
+        param_rng_seed = param_ptr;
         qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
-        BOOTINFODATA(cs->as, parameters_base, BI_RNG_SEED,
+        BOOTINFODATA(param_ptr, BI_RNG_SEED,
                      rng_seed, sizeof(rng_seed));
 
         /* load initrd */
@@ -653,13 +672,19 @@  static void q800_init(MachineState *machine)
             initrd_base = (ram_size - initrd_size) & TARGET_PAGE_MASK;
             load_image_targphys(initrd_filename, initrd_base,
                                 ram_size - initrd_base);
-            BOOTINFO2(cs->as, parameters_base, BI_RAMDISK, initrd_base,
+            BOOTINFO2(param_ptr, BI_RAMDISK, initrd_base,
                       initrd_size);
         } else {
             initrd_base = 0;
             initrd_size = 0;
         }
-        BOOTINFO0(cs->as, parameters_base, BI_LAST);
+        BOOTINFO0(param_ptr, BI_LAST);
+        rom_add_blob_fixed_as("bootinfo", param_blob, param_ptr - param_blob,
+                              parameters_base, cs->as);
+        reset_info->rng_seed = rom_ptr_for_as(cs->as, parameters_base,
+                                              param_ptr - param_blob) +
+                               (param_rng_seed - param_blob);
+        g_free(param_blob);
     } else {
         uint8_t *ptr;
         /* allocate and load BIOS */
diff --git a/hw/m68k/virt.c b/hw/m68k/virt.c
index f7b903ea1b..1b9771442d 100644
--- a/hw/m68k/virt.c
+++ b/hw/m68k/virt.c
@@ -89,6 +89,7 @@  typedef struct {
     M68kCPU *cpu;
     hwaddr initial_pc;
     hwaddr initial_stack;
+    struct bi_record *rng_seed;
 } ResetInfo;
 
 static void main_cpu_reset(void *opaque)
@@ -97,6 +98,11 @@  static void main_cpu_reset(void *opaque)
     M68kCPU *cpu = reset_info->cpu;
     CPUState *cs = CPU(cpu);
 
+    if (reset_info->rng_seed) {
+        qemu_guest_getrandom_nofail((void *)reset_info->rng_seed->data + 2,
+            be16_to_cpu(*(uint16_t *)reset_info->rng_seed->data));
+    }
+
     cpu_reset(cs);
     cpu->env.aregs[7] = reset_info->initial_stack;
     cpu->env.pc = reset_info->initial_pc;
@@ -212,6 +218,7 @@  static void virt_init(MachineState *machine)
     if (kernel_filename) {
         CPUState *cs = CPU(cpu);
         uint64_t high;
+        void *param_blob = g_malloc(1024), *param_ptr, *param_rng_seed;
 
         kernel_size = load_elf(kernel_filename, NULL, NULL, NULL,
                                &elf_entry, NULL, &high, NULL, 1,
@@ -222,35 +229,37 @@  static void virt_init(MachineState *machine)
         }
         reset_info->initial_pc = elf_entry;
         parameters_base = (high + 1) & ~1;
+        param_ptr = param_blob;
 
-        BOOTINFO1(cs->as, parameters_base, BI_MACHTYPE, MACH_VIRT);
-        BOOTINFO1(cs->as, parameters_base, BI_FPUTYPE, FPU_68040);
-        BOOTINFO1(cs->as, parameters_base, BI_MMUTYPE, MMU_68040);
-        BOOTINFO1(cs->as, parameters_base, BI_CPUTYPE, CPU_68040);
-        BOOTINFO2(cs->as, parameters_base, BI_MEMCHUNK, 0, ram_size);
+        BOOTINFO1(param_ptr, BI_MACHTYPE, MACH_VIRT);
+        BOOTINFO1(param_ptr, BI_FPUTYPE, FPU_68040);
+        BOOTINFO1(param_ptr, BI_MMUTYPE, MMU_68040);
+        BOOTINFO1(param_ptr, BI_CPUTYPE, CPU_68040);
+        BOOTINFO2(param_ptr, BI_MEMCHUNK, 0, ram_size);
 
-        BOOTINFO1(cs->as, parameters_base, BI_VIRT_QEMU_VERSION,
+        BOOTINFO1(param_ptr, BI_VIRT_QEMU_VERSION,
                   ((QEMU_VERSION_MAJOR << 24) | (QEMU_VERSION_MINOR << 16) |
                    (QEMU_VERSION_MICRO << 8)));
-        BOOTINFO2(cs->as, parameters_base, BI_VIRT_GF_PIC_BASE,
+        BOOTINFO2(param_ptr, BI_VIRT_GF_PIC_BASE,
                   VIRT_GF_PIC_MMIO_BASE, VIRT_GF_PIC_IRQ_BASE);
-        BOOTINFO2(cs->as, parameters_base, BI_VIRT_GF_RTC_BASE,
+        BOOTINFO2(param_ptr, BI_VIRT_GF_RTC_BASE,
                   VIRT_GF_RTC_MMIO_BASE, VIRT_GF_RTC_IRQ_BASE);
-        BOOTINFO2(cs->as, parameters_base, BI_VIRT_GF_TTY_BASE,
+        BOOTINFO2(param_ptr, BI_VIRT_GF_TTY_BASE,
                   VIRT_GF_TTY_MMIO_BASE, VIRT_GF_TTY_IRQ_BASE);
-        BOOTINFO2(cs->as, parameters_base, BI_VIRT_CTRL_BASE,
+        BOOTINFO2(param_ptr, BI_VIRT_CTRL_BASE,
                   VIRT_CTRL_MMIO_BASE, VIRT_CTRL_IRQ_BASE);
-        BOOTINFO2(cs->as, parameters_base, BI_VIRT_VIRTIO_BASE,
+        BOOTINFO2(param_ptr, BI_VIRT_VIRTIO_BASE,
                   VIRT_VIRTIO_MMIO_BASE, VIRT_VIRTIO_IRQ_BASE);
 
         if (kernel_cmdline) {
-            BOOTINFOSTR(cs->as, parameters_base, BI_COMMAND_LINE,
+            BOOTINFOSTR(param_ptr, BI_COMMAND_LINE,
                         kernel_cmdline);
         }
 
         /* Pass seed to RNG. */
+        param_rng_seed = param_ptr;
         qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed));
-        BOOTINFODATA(cs->as, parameters_base, BI_RNG_SEED,
+        BOOTINFODATA(param_ptr, BI_RNG_SEED,
                      rng_seed, sizeof(rng_seed));
 
         /* load initrd */
@@ -265,13 +274,19 @@  static void virt_init(MachineState *machine)
             initrd_base = (ram_size - initrd_size) & TARGET_PAGE_MASK;
             load_image_targphys(initrd_filename, initrd_base,
                                 ram_size - initrd_base);
-            BOOTINFO2(cs->as, parameters_base, BI_RAMDISK, initrd_base,
+            BOOTINFO2(param_ptr, BI_RAMDISK, initrd_base,
                       initrd_size);
         } else {
             initrd_base = 0;
             initrd_size = 0;
         }
-        BOOTINFO0(cs->as, parameters_base, BI_LAST);
+        BOOTINFO0(param_ptr, BI_LAST);
+        rom_add_blob_fixed_as("bootinfo", param_blob, param_ptr - param_blob,
+                              parameters_base, cs->as);
+        reset_info->rng_seed = rom_ptr_for_as(cs->as, parameters_base,
+                                              param_ptr - param_blob) +
+                               (param_rng_seed - param_blob);
+        g_free(param_blob);
     }
 }