Re: [PATCH v4] arm64: Add purgatory printing

[Simon Horman <horms@verge.net.au>]

On Fri, Oct 16, 2020 at 01:40:57PM +0200, Matthias Brugger wrote:
> Hi,
> 
> On 02/10/2020 20:34, Bhupesh Sharma wrote:
> > Hello Matthias,
> > 
> > Thanks for the updated revision.
> > 
> > On Fri, Oct 2, 2020 at 7:13 PM <matthias.bgg@kernel.org> wrote:
> > > 
> > > From: Matthias Brugger <mbrugger@suse.com>
> > > 
> > > Add option to allow purgatory printing on arm64 hardware
> > > by passing the console name which should be used.
> > > Based on a patch by Geoff Levand.
> > > 
> > > Cc: Geoff Levand <geoff@infradead.org>
> > > Signed-off-by: Matthias Brugger <mbrugger@suse.com>
> > > 
> > > ---
> > > 
> > > Changes in v4:
> > > - fix snprintf error handling
> > > 
> > > Changes in v3:
> > > - check return value of snprintf
> > > 
> > > Changes in v2:
> > > - use sizeof(buffer)
> > > - user serial command option instead of console
> > > - reduce buffer to size 10
> > > - use snprintf
> > > - fix error handling for wrong serial console parameter
> > > - Update help information
> > > 
> > >   kexec/arch/arm64/include/arch/options.h |  6 ++-
> > >   kexec/arch/arm64/kexec-arm64.c          | 71 +++++++++++++++++++++++++
> > >   purgatory/arch/arm64/purgatory-arm64.c  | 17 +++++-
> > >   3 files changed, 92 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/kexec/arch/arm64/include/arch/options.h b/kexec/arch/arm64/include/arch/options.h
> > > index a17d933..8c695f3 100644
> > > --- a/kexec/arch/arm64/include/arch/options.h
> > > +++ b/kexec/arch/arm64/include/arch/options.h
> > > @@ -5,7 +5,8 @@
> > >   #define OPT_DTB                        ((OPT_MAX)+1)
> > >   #define OPT_INITRD             ((OPT_MAX)+2)
> > >   #define OPT_REUSE_CMDLINE      ((OPT_MAX)+3)
> > > -#define OPT_ARCH_MAX           ((OPT_MAX)+4)
> > > +#define OPT_SERIAL             ((OPT_MAX)+4)
> > > +#define OPT_ARCH_MAX           ((OPT_MAX)+5)
> > > 
> > >   #define KEXEC_ARCH_OPTIONS \
> > >          KEXEC_OPTIONS \
> > > @@ -13,6 +14,7 @@
> > >          { "command-line",  1, NULL, OPT_APPEND }, \
> > >          { "dtb",           1, NULL, OPT_DTB }, \
> > >          { "initrd",        1, NULL, OPT_INITRD }, \
> > > +       { "serial",        1, NULL, OPT_SERIAL }, \
> > >          { "ramdisk",       1, NULL, OPT_INITRD }, \
> > >          { "reuse-cmdline", 0, NULL, OPT_REUSE_CMDLINE }, \
> > > 
> > > @@ -25,6 +27,7 @@ static const char arm64_opts_usage[] __attribute__ ((unused)) =
> > >   "     --command-line=STRING Set the kernel command line to STRING.\n"
> > >   "     --dtb=FILE            Use FILE as the device tree blob.\n"
> > >   "     --initrd=FILE         Use FILE as the kernel initial ramdisk.\n"
> > > +"     --serial=STRING       Name of console used for purgatory printing. (e.g. ttyAMA0)\n"
> > >   "     --ramdisk=FILE        Use FILE as the kernel initial ramdisk.\n"
> > >   "     --reuse-cmdline       Use kernel command line from running system.\n";
> > > 
> > > @@ -32,6 +35,7 @@ struct arm64_opts {
> > >          const char *command_line;
> > >          const char *dtb;
> > >          const char *initrd;
> > > +       const char *console;
> > >   };
> > > 
> > >   extern struct arm64_opts arm64_opts;
> > > diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
> > > index 45ebc54..6f572ed 100644
> > > --- a/kexec/arch/arm64/kexec-arm64.c
> > > +++ b/kexec/arch/arm64/kexec-arm64.c
> > > @@ -165,6 +165,8 @@ int arch_process_options(int argc, char **argv)
> > >                          break;
> > >                  case OPT_KEXEC_FILE_SYSCALL:
> > >                          do_kexec_file_syscall = 1;
> > > +               case OPT_SERIAL:
> > > +                       arm64_opts.console = optarg;
> > >                          break;
> > >                  default:
> > >                          break; /* Ignore core and unknown options. */
> > > @@ -180,12 +182,72 @@ int arch_process_options(int argc, char **argv)
> > >          dbgprintf("%s:%d: dtb: %s\n", __func__, __LINE__,
> > >                  (do_kexec_file_syscall && arm64_opts.dtb ? "(ignored)" :
> > >                                                          arm64_opts.dtb));
> > > +       dbgprintf("%s:%d: console: %s\n", __func__, __LINE__,
> > > +               arm64_opts.console);
> > > +
> > >          if (do_kexec_file_syscall)
> > >                  arm64_opts.dtb = NULL;
> > > 
> > >          return 0;
> > >   }
> > > 
> > > +/**
> > > + * find_purgatory_sink - Find a sink for purgatory output.
> > > + */
> > > +
> > > +static uint64_t find_purgatory_sink(const char *console)
> > > +{
> > > +       int fd, ret;
> > > +       char device[255], mem[255];
> > > +       struct stat sb;
> > > +       char buffer[10];
> > > +       uint64_t iomem = 0x0;
> > > +
> > > +       if (!console)
> > > +               return 0;
> > > +
> > > +       ret = snprintf(device, sizeof(device), "/sys/class/tty/%s", console);
> > > +       if (ret < 0 || ret >= sizeof(device)) {
> > > +               fprintf(stderr, "snprintf failed: %s\n", strerror(errno));
> > > +               return 0;
> > > +       }
> > > +
> > > +       if (stat(device, &sb) || !S_ISDIR(sb.st_mode)) {
> > > +               fprintf(stderr, "kexec: %s: No valid console found for %s\n",
> > > +                       __func__, device);
> > > +               return 0;
> > > +       }
> > > +
> > > +       ret = snprintf(mem, sizeof(mem), "%s%s", device, "/iomem_base");
> > > +       if (ret < 0 || ret >= sizeof(mem)) {
> > > +               fprintf(stderr, "snprintf failed: %s\n", strerror(errno));
> > > +               return 0;
> > > +       }
> > > +
> > > +       printf("console memory read from %s\n", mem);
> > > +
> > > +       fd = open(mem, O_RDONLY);
> > > +       if (fd < 0) {
> > > +               fprintf(stderr, "kexec: %s: No able to open %s\n",
> > > +                       __func__, mem);
> > > +               return 0;
> > > +       }
> > > +
> > > +       memset(buffer, '\0', sizeof(buffer));
> > > +       ret = read(fd, buffer, sizeof(buffer));
> > > +       if (ret < 0) {
> > > +               fprintf(stderr, "kexec: %s: not able to read fd\n", __func__);
> > > +               close(fd);
> > > +               return 0;
> > > +       }
> > > +
> > > +       sscanf(buffer, "%lx", &iomem);
> > > +       printf("console memory is at %#lx\n", iomem);
> > > +
> > > +       close(fd);
> > > +       return iomem;
> > > +}
> > > +
> > >   /**
> > >    * struct dtb - Info about a binary device tree.
> > >    *
> > > @@ -637,6 +699,7 @@ int arm64_load_other_segments(struct kexec_info *info,
> > >          unsigned long hole_min;
> > >          unsigned long hole_max;
> > >          unsigned long initrd_end;
> > > +       uint64_t purgatory_sink;
> > >          char *initrd_buf = NULL;
> > >          struct dtb dtb;
> > >          char command_line[COMMAND_LINE_SIZE] = "";
> > > @@ -654,6 +717,11 @@ int arm64_load_other_segments(struct kexec_info *info,
> > >                  command_line[sizeof(command_line) - 1] = 0;
> > >          }
> > > 
> > > +       purgatory_sink = find_purgatory_sink(arm64_opts.console);
> > > +
> > > +       dbgprintf("%s:%d: purgatory sink: 0x%" PRIx64 "\n", __func__, __LINE__,
> > > +               purgatory_sink);
> > > +
> > >          if (arm64_opts.dtb) {
> > >                  dtb.name = "dtb_user";
> > >                  dtb.buf = slurp_file(arm64_opts.dtb, &dtb.size);
> > > @@ -742,6 +810,9 @@ int arm64_load_other_segments(struct kexec_info *info,
> > > 
> > >          info->entry = (void *)elf_rel_get_addr(&info->rhdr, "purgatory_start");
> > > 
> > > +       elf_rel_set_symbol(&info->rhdr, "arm64_sink", &purgatory_sink,
> > > +               sizeof(purgatory_sink));
> > > +
> > >          elf_rel_set_symbol(&info->rhdr, "arm64_kernel_entry", &image_base,
> > >                  sizeof(image_base));
> > > 
> > > diff --git a/purgatory/arch/arm64/purgatory-arm64.c b/purgatory/arch/arm64/purgatory-arm64.c
> > > index fe50fcf..b4d8578 100644
> > > --- a/purgatory/arch/arm64/purgatory-arm64.c
> > > +++ b/purgatory/arch/arm64/purgatory-arm64.c
> > > @@ -5,15 +5,30 @@
> > >   #include <stdint.h>
> > >   #include <purgatory.h>
> > > 
> > > +/* Symbols set by kexec. */
> > > +
> > > +uint8_t *arm64_sink __attribute__ ((section ("data")));
> > > +extern void (*arm64_kernel_entry)(uint64_t, uint64_t, uint64_t, uint64_t);
> > > +extern uint64_t arm64_dtb_addr;
> > > +
> > >   void putchar(int ch)
> > >   {
> > > -       /* Nothing for now */
> > > +       if (!arm64_sink)
> > > +               return;
> > > +
> > > +       *arm64_sink = ch;
> > > +
> > > +       if (ch == '\n')
> > > +               *arm64_sink = '\r';
> > >   }
> > > 
> > >   void post_verification_setup_arch(void)
> > >   {
> > > +       printf("purgatory: booting kernel now\n");
> > >   }
> > > 
> > >   void setup_arch(void)
> > >   {
> > > +       printf("purgatory: entry=%lx\n", (unsigned long)arm64_kernel_entry);
> > > +       printf("purgatory: dtb=%lx\n", arm64_dtb_addr);
> > >   }
> > > --
> > > 2.28.0
> > 
> > Looks good to me, so:
> > Acked-by: Bhupesh Sharma <bhsharma@redhat.com>
> > 
> 
> Simon: friendly reminder of this patch. Please let me know if you have any
> concerns regarding the patch.
> 
> Best regards,
> Matthias
> 

Sorry for the extended delay,
I've applied and pushed this change.

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