[12/12] hw/riscv: spike: Decouple create_fdt() dependency to ELF loading

At present create_fdt() calls htif_uses_elf_symbols() to determine
whether to insert a <reg> property for the HTIF. This unfortunately
creates a hidden dependency to riscv_load_{firmware,kernel} that
create_fdt() must be called after the ELF {firmware,kernel} image
has been loaded.

Decouple such dependency be adding a new parameter to create_fdt(),
whether custom HTIF base address is used. The flag will be set if
non ELF {firmware,kernel} image is given by user.

Signed-off-by: Bin Meng <bmeng@tinylab.org>

---

 include/hw/char/riscv_htif.h |  5 +---
 hw/char/riscv_htif.c         | 17 +++++-------
 hw/riscv/spike.c             | 54 ++++++++++++++++++++++++++++++------
 3 files changed, 53 insertions(+), 23 deletions(-)

Hi Bin,

On 12/27/22 03:48, Bin Meng wrote:
> At present create_fdt() calls htif_uses_elf_symbols() to determine
> whether to insert a <reg> property for the HTIF. This unfortunately
> creates a hidden dependency to riscv_load_{firmware,kernel} that
> create_fdt() must be called after the ELF {firmware,kernel} image
> has been loaded.
>
> Decouple such dependency be adding a new parameter to create_fdt(),
> whether custom HTIF base address is used. The flag will be set if
> non ELF {firmware,kernel} image is given by user.
>
> Signed-off-by: Bin Meng <bmeng@tinylab.org>
>
> ---
>
>   include/hw/char/riscv_htif.h |  5 +---
>   hw/char/riscv_htif.c         | 17 +++++-------
>   hw/riscv/spike.c             | 54 ++++++++++++++++++++++++++++++------
>   3 files changed, 53 insertions(+), 23 deletions(-)
>
> diff --git a/include/hw/char/riscv_htif.h b/include/hw/char/riscv_htif.h
> index 9e8ebbe017..5958c5b986 100644
> --- a/include/hw/char/riscv_htif.h
> +++ b/include/hw/char/riscv_htif.h
> @@ -44,11 +44,8 @@ typedef struct HTIFState {
>   void htif_symbol_callback(const char *st_name, int st_info, uint64_t st_value,
>       uint64_t st_size);
>   
> -/* Check if HTIF uses ELF symbols */
> -bool htif_uses_elf_symbols(void);
> -
>   /* legacy pre qom */
>   HTIFState *htif_mm_init(MemoryRegion *address_space, Chardev *chr,
> -                        uint64_t nonelf_base);
> +                        uint64_t nonelf_base, bool custom_base);
>   
>   #endif
> diff --git a/hw/char/riscv_htif.c b/hw/char/riscv_htif.c
> index 1477fc0090..098de50e35 100644
> --- a/hw/char/riscv_htif.c
> +++ b/hw/char/riscv_htif.c
> @@ -52,20 +52,17 @@
>   #define PK_SYS_WRITE            64
>   
>   static uint64_t fromhost_addr, tohost_addr;
> -static int address_symbol_set;
>   
>   void htif_symbol_callback(const char *st_name, int st_info, uint64_t st_value,
>                             uint64_t st_size)
>   {
>       if (strcmp("fromhost", st_name) == 0) {
> -        address_symbol_set |= 1;
>           fromhost_addr = st_value;
>           if (st_size != 8) {
>               error_report("HTIF fromhost must be 8 bytes");
>               exit(1);
>           }
>       } else if (strcmp("tohost", st_name) == 0) {
> -        address_symbol_set |= 2;
>           tohost_addr = st_value;
>           if (st_size != 8) {
>               error_report("HTIF tohost must be 8 bytes");
> @@ -275,19 +272,19 @@ static const MemoryRegionOps htif_mm_ops = {
>       .write = htif_mm_write,
>   };
>   
> -bool htif_uses_elf_symbols(void)
> -{
> -    return (address_symbol_set == 3) ? true : false;
> -}
> -
>   HTIFState *htif_mm_init(MemoryRegion *address_space, Chardev *chr,
> -                        uint64_t nonelf_base)
> +                        uint64_t nonelf_base, bool custom_base)
>   {
>       uint64_t base, size, tohost_offset, fromhost_offset;
>   
> -    if (!htif_uses_elf_symbols()) {
> +    if (custom_base) {
>           fromhost_addr = nonelf_base;
>           tohost_addr = nonelf_base + 8;
> +    } else {
> +        if (!fromhost_addr || !tohost_addr) {
> +            error_report("Invalid HTIF fromhost or tohost address");
> +            exit(1);
> +        }
>       }
>   
>       base = MIN(tohost_addr, fromhost_addr);
> diff --git a/hw/riscv/spike.c b/hw/riscv/spike.c
> index 810a18f283..90f9e581e4 100644
> --- a/hw/riscv/spike.c
> +++ b/hw/riscv/spike.c
> @@ -50,7 +50,8 @@ static const MemMapEntry spike_memmap[] = {
>   };
>   
>   static void create_fdt(SpikeState *s, const MemMapEntry *memmap,
> -                       uint64_t mem_size, const char *cmdline, bool is_32_bit)
> +                       uint64_t mem_size, const char *cmdline,
> +                       bool is_32_bit, bool htif_custom_base)
>   {
>       void *fdt;
>       uint64_t addr, size;
> @@ -78,7 +79,7 @@ static void create_fdt(SpikeState *s, const MemMapEntry *memmap,
>   
>       qemu_fdt_add_subnode(fdt, "/htif");
>       qemu_fdt_setprop_string(fdt, "/htif", "compatible", "ucb,htif0");
> -    if (!htif_uses_elf_symbols()) {
> +    if (htif_custom_base) {
>           qemu_fdt_setprop_cells(fdt, "/htif", "reg",
>               0x0, memmap[SPIKE_HTIF].base, 0x0, memmap[SPIKE_HTIF].size);
>       }
> @@ -184,6 +185,21 @@ static void create_fdt(SpikeState *s, const MemMapEntry *memmap,
>       }
>   }
>   
> +static bool spike_test_elf_image(char *filename)
> +{
> +    Error *err = NULL;
> +
> +    if (filename) {
> +        load_elf_hdr(filename, NULL, NULL, &err);
> +        if (err) {
> +            error_free(err);
> +            return false;
> +        }
> +    }
> +
> +    return true;
> +}
> +
>   static void spike_board_init(MachineState *machine)
>   {
>       const MemMapEntry *memmap = spike_memmap;
> @@ -191,11 +207,12 @@ static void spike_board_init(MachineState *machine)
>       MemoryRegion *system_memory = get_system_memory();
>       MemoryRegion *mask_rom = g_new(MemoryRegion, 1);
>       target_ulong firmware_end_addr, kernel_start_addr;
> -    const char *firmware_name;
> +    char *firmware_name;
>       uint32_t fdt_load_addr;
>       uint64_t kernel_entry;
>       char *soc_name;
>       int i, base_hartid, hart_count;
> +    bool htif_custom_base;
>   
>       /* Check socket count limit */
>       if (SPIKE_SOCKETS_MAX < riscv_socket_count(machine)) {
> @@ -257,10 +274,28 @@ static void spike_board_init(MachineState *machine)
>       memory_region_add_subregion(system_memory, memmap[SPIKE_MROM].base,
>                                   mask_rom);
>   
> -    firmware_name = riscv_default_firmware_name(&s->soc[0]);
> -    firmware_end_addr = riscv_find_and_load_firmware(machine, firmware_name,
> -                                                     memmap[SPIKE_DRAM].base,
> -                                                     htif_symbol_callback);
> +    /* Find firmware */
> +    firmware_name = riscv_find_firmware(machine->firmware,
> +                        riscv_default_firmware_name(&s->soc[0]));
> +
> +    /*
> +     * Test the given firmware or kernel file to see if it is an ELF image.
> +     * If it is an ELF, we assume it contains the symbols required for
> +     * the HTIF console, otherwise we fall back to use the custom base
> +     * passed from device tree for the HTIF console.
> +     */
> +    htif_custom_base = !spike_test_elf_image(firmware_name);
> +    if (!htif_custom_base) {
> +        htif_custom_base = !spike_test_elf_image(machine->kernel_filename);
> +    }
> +
> +    /* Load firmware */
> +    if (firmware_name) {
> +        firmware_end_addr = riscv_load_firmware(firmware_name,
> +                                                memmap[SPIKE_DRAM].base,
> +                                                htif_symbol_callback);
> +        g_free(firmware_name);
> +    }
>   
>       /* Load kernel */
>       if (machine->kernel_filename) {

'make' is giving me a maybe-uninitialized error in this point:

../hw/riscv/spike.c: In function ‘spike_board_init’:
../hw/riscv/spike.c:301:29: error: ‘firmware_end_addr’ may be used uninitialized [-Werror=maybe-uninitialized]
   301 |         kernel_start_addr = riscv_calc_kernel_start_addr(&s->soc[0],
       | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   302 | firmware_end_addr);
       | ~~~~~~~~~~~~~~~~~~
../hw/riscv/spike.c:208:18: note: ‘firmware_end_addr’ was declared here
   208 |     target_ulong firmware_end_addr, kernel_start_addr;
       |                  ^~~~~~~~~~~~~~~~~


The full context:


     /* Load firmware */
     if (firmware_name) {
         firmware_end_addr = riscv_load_firmware(firmware_name,
memmap[SPIKE_DRAM].base,
htif_symbol_callback);
         g_free(firmware_name);
     }

     /* Load kernel */
     if (machine->kernel_filename) {
         kernel_start_addr = riscv_calc_kernel_start_addr(&s->soc[0],
firmware_end_addr);

         kernel_entry = riscv_load_kernel(machine->kernel_filename,
                                          kernel_start_addr,
                                          htif_symbol_callback);
     } else {


The error is happening because, with this patch, 'firmware_end_addr' may not be
initialized via riscv_load_firmware() because we're not guaranteeing that
'firmware_name' will be valid.

riscv_load_firmware() is guaranteed to either return > 0 or error out with exit(1),
so a simple fix would be to initialize 'firmware_end_addr' with 0.



Thanks,

Daniel


> @@ -280,7 +315,7 @@ static void spike_board_init(MachineState *machine)
>   
>       /* Create device tree */
>       create_fdt(s, memmap, machine->ram_size, machine->kernel_cmdline,
> -               riscv_is_32bit(&s->soc[0]));
> +               riscv_is_32bit(&s->soc[0]), htif_custom_base);
>   
>       /* Load initrd */
>       if (machine->kernel_filename && machine->initrd_filename) {
> @@ -308,7 +343,8 @@ static void spike_board_init(MachineState *machine)
>                                 fdt_load_addr);
>   
>       /* initialize HTIF using symbols found in load_kernel */
> -    htif_mm_init(system_memory, serial_hd(0), memmap[SPIKE_HTIF].base);
> +    htif_mm_init(system_memory, serial_hd(0), memmap[SPIKE_HTIF].base,
> +                 htif_custom_base);
>   }
>   
>   static void spike_machine_instance_init(Object *obj)