Re: [Qemu-devel] [PATCH v1 for-2.13 3/4] pc-bios/s390-ccw/net: Add support for pxelinux-style config files

[Viktor VM Mihajlovski]

On 18.04.2018 14:31, Thomas Huth wrote:
> Since it is quite cumbersome to manually create a combined kernel with
> initrd image for network booting, we now support loading via pxelinux
> configuration files, too. In these files, the kernel, initrd and command
> line parameters can be specified seperately, and the firmware then takes
> care of glueing everything together in memory after the files have been
> downloaded.
> 
> Signed-off-by: Thomas Huth <address@hidden>
> ---
>  pc-bios/s390-ccw/netboot.mak |   5 +-
>  pc-bios/s390-ccw/netmain.c   | 203 
> +++++++++++++++++++++++++++++++++++++++++--
>  2 files changed, 201 insertions(+), 7 deletions(-)
> 
> diff --git a/pc-bios/s390-ccw/netboot.mak b/pc-bios/s390-ccw/netboot.mak
> index a25d238..8db9573 100644
> --- a/pc-bios/s390-ccw/netboot.mak
> +++ b/pc-bios/s390-ccw/netboot.mak
> @@ -24,8 +24,9 @@ CTYPE_OBJS = isdigit.o isxdigit.o toupper.o
>  %.o : $(SLOF_DIR)/lib/libc/ctype/%.c
>       $(call quiet-command,$(CC) $(LIBC_CFLAGS) -c -o $@ 
> $<,"CC","$(TARGET_DIR)$@")
> 
> -STRING_OBJS = strcat.o strchr.o strcmp.o strcpy.o strlen.o strncmp.o 
> strncpy.o \
> -           strstr.o memset.o memcpy.o memmove.o memcmp.o
> +STRING_OBJS = strcasecmp.o strcat.o strchr.o strcmp.o strcpy.o strlen.o \
> +           strncasecmp.o strncmp.o strncpy.o strstr.o \
> +           memset.o memcpy.o memmove.o memcmp.o
>  %.o : $(SLOF_DIR)/lib/libc/string/%.c
>       $(call quiet-command,$(CC) $(LIBC_CFLAGS) -c -o $@ 
> $<,"CC","$(TARGET_DIR)$@")
> 
> diff --git a/pc-bios/s390-ccw/netmain.c b/pc-bios/s390-ccw/netmain.c
> index e11ed4e..fa62bfe 100644
> --- a/pc-bios/s390-ccw/netmain.c
> +++ b/pc-bios/s390-ccw/netmain.c
> @@ -39,11 +39,17 @@
> 
>  extern char _start[];
> 
> +#define KERNEL_ADDR             ((void *)0L)
> +#define KERNEL_MAX_SIZE         ((long)_start)
> +#define ARCH_COMMAND_LINE_SIZE  896              /* Taken from Linux kernel 
> */
> +
>  char stack[PAGE_SIZE * 8] __attribute__((aligned(PAGE_SIZE)));
>  IplParameterBlock iplb __attribute__((aligned(PAGE_SIZE)));
> +static char cfgbuf[2048];
> 
>  static SubChannelId net_schid = { .one = 1 };
>  static int ip_version = 4;
> +static uint8_t mac[6];
>  static uint64_t dest_timer;
> 
>  static uint64_t get_timer_ms(void)
> @@ -136,9 +142,15 @@ static int tftp_load(filename_ip_t *fnip, void *buffer, 
> int len)
>      rc = tftp(fnip, buffer, len, DEFAULT_TFTP_RETRIES, &tftp_err, 1, 1428,
>                ip_version);
> 
> -    if (rc > 0) {
> -        printf("  TFTP: Received %s (%d KBytes)\n", fnip->filename,
> -               rc / 1024);
> +    if (rc < 0) {
> +        /* Make sure that error messages are put into a new line */
> +        printf("\n  ");
> +    }
> +
> +    if (rc > 1024) {
> +        printf("  TFTP: Received %s (%d KBytes)\n", fnip->filename, rc / 
> 1024);
> +    } else if (rc > 0) {
> +        printf("  TFTP: Received %s (%d Bytes)\n", fnip->filename, rc);
>      } else if (rc == -1) {
>          puts("unknown TFTP error");
>      } else if (rc == -2) {
> @@ -201,7 +213,6 @@ static int tftp_load(filename_ip_t *fnip, void *buffer, 
> int len)
> 
>  static int net_init(filename_ip_t *fn_ip)
>  {
> -    uint8_t mac[6];
>      int rc;
> 
>      memset(fn_ip, 0, sizeof(filename_ip_t));
> @@ -276,6 +287,183 @@ static void net_uninit(filename_ip_t *fn_ip)
>      virtio_net_uninit();
>  }
> 
> +/* This structure holds the data from one pxelinux.cfg file entry */
> +struct lkia {
> +    const char *label;
> +    const char *kernel;
> +    const char *initrd;
> +    const char *append;
> +};
> +
> +static int load_kernel_with_initrd(filename_ip_t *fn_ip, struct lkia *kia)
> +{
> +    int rc;
> +
> +    printf("Loading pxelinux.cfg entry '%s'\n", kia->label);
> +
> +    if (!kia->kernel) {
> +        printf("Kernel entry is missing!\n");
> +        return -1;
> +    }
> +
> +    strncpy((char *)&fn_ip->filename, kia->kernel, sizeof(fn_ip->filename));
> +    rc = tftp_load(fn_ip, KERNEL_ADDR, KERNEL_MAX_SIZE);
> +    if (rc < 0) {
> +        return rc;
> +    }
> +
> +    if (kia->initrd) {
> +        uint64_t iaddr = (rc + 0xfff) & ~0xfffUL;
> +
> +        strncpy((char *)&fn_ip->filename, kia->initrd, 
> sizeof(fn_ip->filename));
> +        rc = tftp_load(fn_ip, (void *)iaddr, KERNEL_MAX_SIZE - iaddr);
> +        if (rc < 0) {
> +            return rc;
> +        }
> +        /* Patch location and size: */
> +        *(uint64_t *)0x10408 = iaddr;
> +        *(uint64_t *)0x10410 = rc;
> +        rc += iaddr;
> +    }
> +
> +    if (kia->append) {
> +        strncpy((char *)0x10480, kia->append, ARCH_COMMAND_LINE_SIZE);
> +    }
> +
> +    return rc;
> +}
> +
> +#define MAX_PXELINUX_ENTRIES 16
> +
> +/**
> + * Parse a pxelinux-style configuration file.
> + * See the following URL for more inforation about the config file syntax:
> + * https://www.syslinux.org/wiki/index.php?title=PXELINUX
> + */
> +static int handle_pxelinux_cfg(filename_ip_t *fn_ip, char *cfg, int cfgsize)
> +{
> +    struct lkia entries[MAX_PXELINUX_ENTRIES];
> +    int num_entries = 0;
> +    char *ptr = cfg, *eol, *arg;
> +    char *defaultlabel = NULL;
> +    int def_ent = 0;
> +
> +    while (ptr < cfg + cfgsize && num_entries < MAX_PXELINUX_ENTRIES) {
> +        eol = strchr(ptr, '\n');
> +        if (!eol) {
> +            eol = cfg + cfgsize;
> +        }
> +        if (eol > ptr && *(eol - 1) == '\r') {
> +            *(eol - 1) = 0;
> +        }
> +        *eol = '\0';
> +        while (*ptr == ' ' || *ptr == '\t') {
> +            ptr++;
> +        }
> +        if (*ptr == 0 || *ptr == '#') {   /* Ignore comments and empty lines 
> */
> +            goto nextline;
> +        }
> +        arg = strchr(ptr, ' ');    /* Look for space between command and arg 
> */
> +        if (!arg) {
> +            arg = strchr(ptr, '\t');
> +        }
> +        if (!arg) {
> +            printf("Failed to parse the following line:\n %s\n", ptr);
> +            goto nextline;
> +        }
> +        *arg++ = 0;
> +        while (*arg == ' ' || *arg == '\t') {
> +            arg++;
> +        }
> +        if (!strcasecmp("default", ptr)) {
> +            defaultlabel = arg;
> +        } else if (!strcasecmp("label", ptr)) {
> +            entries[num_entries].label = arg;
> +            if (defaultlabel && !strcmp(arg, defaultlabel)) {
> +                def_ent = num_entries;
> +            }
> +            num_entries++;
> +        } else if (!strcasecmp("kernel", ptr)) {
> +            entries[num_entries - 1].kernel = arg;
> +        } else if (!strcasecmp("initrd", ptr)) {
> +            entries[num_entries - 1].initrd = arg;
> +        } else if (!strcasecmp("append", ptr)) {
> +            entries[num_entries - 1].append = arg;
> +        } else {
> +            printf("Command '%s' is not supported.\n", ptr);
> +        }
> +nextline:
> +        ptr = eol + 1;
> +    }
> +
> +    return load_kernel_with_initrd(fn_ip, &entries[def_ent]);
> +}
> +
> +static int net_try_pxelinux_cfgs(filename_ip_t *fn_ip)
> +{
> +    int rc, idx;
> +
> +    cfgbuf[sizeof(cfgbuf) - 1] = 0;   /* Make sure that it is NUL-terminated 
> */
> +
> +    printf("Trying pxelinux.cfg files...\n");
> +
> +    /* Look for config file with MAC address in its name */
> +    sprintf((char *)fn_ip->filename,
> +            "pxelinux.cfg/%02x-%02x-%02x-%02x-%02x-%02x",
> +            mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
> +    rc = tftp_load(fn_ip, cfgbuf, sizeof(cfgbuf) - 1);
> +    if (rc > 0) {
> +        return handle_pxelinux_cfg(fn_ip, cfgbuf, sizeof(cfgbuf));
> +    }
> +
> +    /* Look for config file with IP address in its name */
> +    if (ip_version == 4) {
> +        for (idx = 0; idx <= 7; idx++) {
> +            sprintf((char *)fn_ip->filename,
> +                    "pxelinux.cfg/%02X%02X%02X%02X",
> +                    (fn_ip->own_ip >> 24) & 0xff, (fn_ip->own_ip >> 16) & 
> 0xff,
> +                    (fn_ip->own_ip >> 8) & 0xff, fn_ip->own_ip & 0xff);
> +            fn_ip->filename[strlen((char *)fn_ip->filename) - idx] = 0;
> +            rc = tftp_load(fn_ip, cfgbuf, sizeof(cfgbuf) - 1);
> +            if (rc > 0) {
> +                return handle_pxelinux_cfg(fn_ip, cfgbuf, sizeof(cfgbuf));
> +            }
> +        }
> +    }
> +
> +    /* Try "default" config file */
> +    strcpy((char *)fn_ip->filename, "pxelinux.cfg/default");
> +    rc = tftp_load(fn_ip, cfgbuf, sizeof(cfgbuf) - 1);
> +    if (rc > 0) {
> +        return handle_pxelinux_cfg(fn_ip, cfgbuf, sizeof(cfgbuf));
> +    }
> +
> +    return -1;
> +}
> +
> +static int net_try_direct_tftp_load(filename_ip_t *fn_ip)
> +{
> +    int rc;
> +    void *baseaddr = (void *)0x2000;  /* Load right after the low-core */
> +
> +    rc = tftp_load(fn_ip, baseaddr, KERNEL_MAX_SIZE - (long)baseaddr);
> +
> +    if (rc > 0 && rc < sizeof(cfgbuf) - 1) {
> +        /* Check whether it is a configuration file instead of a kernel */
That's interesting because treating the bootfile as pxe-ish config is
what DPM does. Which means that with this change the processor
architecture type 0x1f (Basic) will turn into a superset of 0x20
(Extended). I guess this should be documented somewhere(TM) to avoid
confusion.
> +        memcpy(cfgbuf, baseaddr, rc);
> +        cfgbuf[rc] = 0;    /* Make sure that it is NUL-terminated */
> +        if (!strncasecmp("default", cfgbuf, 7) || !strncmp("# ", cfgbuf, 2)) 
> {
> +            /* Looks like it is a pxelinux.cfg */
> +            return handle_pxelinux_cfg(fn_ip, cfgbuf, rc);> +        }
> +    }
> +
> +    /* Move kernel to right location */
> +    memmove(KERNEL_ADDR, baseaddr, rc);
Move this into the if block above. If the tftp_load fails with rc < 0
bad things will happen...
> +
> +    return rc;
> +}
> +
>  void panic(const char *string)
>  {
>      sclp_print(string);
> @@ -360,7 +548,12 @@ void main(void)
>          panic("Network initialization failed. Halting.\n");
>      }
> 
> -    rc = tftp_load(&fn_ip, NULL, (long)_start);
> +    if (strlen((char *)fn_ip.filename) > 0) {
> +        rc = net_try_direct_tftp_load(&fn_ip);
> +    }
> +    if (rc <= 0) {
> +        rc = net_try_pxelinux_cfgs(&fn_ip);
> +    }
> 
>      net_uninit(&fn_ip);
> 


-- 
Regards,
  Viktor Mihajlovski