Re: [Xen-devel] [PATCH v2] kexec: implemented XEN KEXEC STATUS to determine if an image is loaded

[Baoquan He <bhe@xxxxxxxxxx>]

Hi,

I don't strongly oppose against this, but could you tell what you have
met makes the kexec_loaded/kexec_crash_loaded checking not convenient to
you?

Thanks
Baoquan


On 01/20/17 at 11:03am, Eric DeVolder wrote:
> Instead of the scripts having to poke at various fields we can
> provide that functionality via the -S parameter.
> 
> Returns 0 if the payload is loaded. Can be used in combination
> with -l or -p to get the state of the proper kexec image.
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Signed-off-by: Eric DeVolder <eric.devolder@xxxxxxxxxx>
> ---
> Note: The corresponding Xen changes have been committed
> to the Xen staging branch. Follow this thread:
> https://lists.xenproject.org/archives/html/xen-devel/2017-01/msg01570.html
> 
> CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: kexec@xxxxxxxxxxxxxxxxxxx
> CC: xen-devel@xxxxxxxxxxxxxxxxxxxx
> CC: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
> 
> v0: First version (internal product).
> v1: Posted on kexec mailing list. Changed -s to -S
> v2: Incorporated feedback from kexec mailing list
> ---
>  configure.ac      |  8 ++++++-
>  kexec/kexec-xen.c | 26 +++++++++++++++++++++++
>  kexec/kexec.8     |  6 ++++++
>  kexec/kexec.c     | 62 
> ++++++++++++++++++++++++++++++++++++++++++++++++-------
>  kexec/kexec.h     |  5 ++++-
>  5 files changed, 98 insertions(+), 9 deletions(-)
> 
> diff --git a/configure.ac b/configure.ac
> index 3044185..c6e864b 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -165,8 +165,14 @@ fi
>  dnl find Xen control stack libraries
>  if test "$with_xen" = yes ; then
>       AC_CHECK_HEADER(xenctrl.h,
> -             [AC_CHECK_LIB(xenctrl, xc_kexec_load, ,
> +             [AC_CHECK_LIB(xenctrl, xc_kexec_load, [ have_xenctrl_h=yes ],
>               AC_MSG_NOTICE([Xen support disabled]))])
> +if test "$have_xenctrl_h" = yes ; then
> +     AC_CHECK_LIB(xenctrl, xc_kexec_status,
> +             AC_DEFINE(HAVE_KEXEC_CMD_STATUS, 1,
> +                     [The kexec_status call is available]),
> +             AC_MSG_NOTICE([The kexec_status call is not available]))
> +fi
>  fi
>  
>  dnl ---Sanity checks
> diff --git a/kexec/kexec-xen.c b/kexec/kexec-xen.c
> index 24a4191..2b448d3 100644
> --- a/kexec/kexec-xen.c
> +++ b/kexec/kexec-xen.c
> @@ -105,6 +105,27 @@ int xen_kexec_unload(uint64_t kexec_flags)
>       return ret;
>  }
>  
> +int xen_kexec_status(uint64_t kexec_flags)
> +{
> +     xc_interface *xch;
> +     uint8_t type;
> +     int ret = -1;
> +
> +#ifdef HAVE_KEXEC_CMD_STATUS
> +     xch = xc_interface_open(NULL, NULL, 0);
> +     if (!xch)
> +             return -1;
> +
> +     type = (kexec_flags & KEXEC_ON_CRASH) ? KEXEC_TYPE_CRASH : 
> KEXEC_TYPE_DEFAULT;
> +
> +     ret = xc_kexec_status(xch, type);
> +
> +     xc_interface_close(xch);
> +#endif
> +
> +     return ret;
> +}
> +
>  void xen_kexec_exec(void)
>  {
>       xc_interface *xch;
> @@ -130,6 +151,11 @@ int xen_kexec_unload(uint64_t kexec_flags)
>       return -1;
>  }
>  
> +int xen_kexec_status(uint64_t kexec_flags)
> +{
> +     return -1;
> +}
> +
>  void xen_kexec_exec(void)
>  {
>  }
> diff --git a/kexec/kexec.8 b/kexec/kexec.8
> index 4d0c1d1..f4b39a6 100644
> --- a/kexec/kexec.8
> +++ b/kexec/kexec.8
> @@ -107,6 +107,12 @@ command:
>  .B \-d\ (\-\-debug)
>  Enable debugging messages.
>  .TP
> +.B \-S\ (\-\-status)
> +Return 0 if the type (by default crash) is loaded. Can be used in conjuction
> +with -l or -p to toggle the type. Note this option supersedes other options
> +and it will
> +.BR not\ load\ or\ unload\ the\ kernel.
> +.TP
>  .B \-e\ (\-\-exec)
>  Run the currently loaded kernel. Note that it will reboot into the loaded 
> kernel without calling shutdown(8).
>  .TP
> diff --git a/kexec/kexec.c b/kexec/kexec.c
> index 500e5a9..defbbe3 100644
> --- a/kexec/kexec.c
> +++ b/kexec/kexec.c
> @@ -51,6 +51,9 @@
>  #include "kexec-lzma.h"
>  #include <arch/options.h>
>  
> +#define KEXEC_LOADED_PATH "/sys/kernel/kexec_loaded"
> +#define KEXEC_CRASH_LOADED_PATH "/sys/kernel/kexec_crash_loaded"
> +
>  unsigned long long mem_min = 0;
>  unsigned long long mem_max = ULONG_MAX;
>  static unsigned long kexec_flags = 0;
> @@ -58,6 +61,8 @@ static unsigned long kexec_flags = 0;
>  static unsigned long kexec_file_flags = 0;
>  int kexec_debug = 0;
>  
> +static int kexec_loaded(const char *file);
> +
>  void dbgprint_mem_range(const char *prefix, struct memory_range *mr, int 
> nr_mr)
>  {
>       int i;
> @@ -890,8 +895,6 @@ static int my_exec(void)
>       return -1;
>  }
>  
> -static int kexec_loaded(void);
> -
>  static int load_jump_back_helper_image(unsigned long kexec_flags, void 
> *entry)
>  {
>       int result;
> @@ -909,7 +912,7 @@ static int my_load_jump_back_helper(unsigned long 
> kexec_flags, void *entry)
>  {
>       int result;
>  
> -     if (kexec_loaded()) {
> +     if (kexec_loaded(KEXEC_LOADED_PATH)) {
>               fprintf(stderr, "There is kexec kernel loaded, make sure "
>                       "you are in kexeced kernel.\n");
>               return -1;
> @@ -970,6 +973,7 @@ void usage(void)
>              "                      to original kernel.\n"
>              " -s, --kexec-file-syscall Use file based syscall for kexec 
> operation\n"
>              " -d, --debug           Enable debugging to help spot a 
> failure.\n"
> +            " -S, --status         Return 0 if the type (by default crash) 
> is loaded.\n"
>              "\n"
>              "Supported kernel file types and options: \n");
>       for (i = 0; i < file_types; i++) {
> @@ -981,7 +985,7 @@ void usage(void)
>       printf("\n");
>  }
>  
> -static int kexec_loaded(void)
> +static int kexec_loaded(const char *file)
>  {
>       long ret = -1;
>       FILE *fp;
> @@ -992,7 +996,7 @@ static int kexec_loaded(void)
>       if (xen_present())
>               return 1;
>  
> -     fp = fopen("/sys/kernel/kexec_loaded", "r");
> +     fp = fopen(file, "r");
>       if (fp == NULL)
>               return -1;
>  
> @@ -1015,6 +1019,30 @@ static int kexec_loaded(void)
>       return (int)ret;
>  }
>  
> +static int k_status(unsigned long kexec_flags)
> +{
> +     int result;
> +     long native_arch;
> +
> +     /* set the arch */
> +     native_arch = physical_arch();
> +     if (native_arch < 0) {
> +             return -1;
> +     }
> +     kexec_flags |= native_arch;
> +
> +     if (xen_present())
> +             result = xen_kexec_status(kexec_flags);
> +     else {
> +             if (kexec_flags & KEXEC_ON_CRASH)
> +                     result = kexec_loaded(KEXEC_CRASH_LOADED_PATH);
> +             else
> +                     result = kexec_loaded(KEXEC_LOADED_PATH);
> +     }
> +     return result;
> +}
> +
> +
>  /*
>   * Remove parameter from a kernel command line. Helper function by 
> get_command_line().
>   */
> @@ -1204,6 +1232,7 @@ int main(int argc, char *argv[])
>       int do_unload = 0;
>       int do_reuse_initrd = 0;
>       int do_kexec_file_syscall = 0;
> +     int do_status = 0;
>       void *entry = 0;
>       char *type = 0;
>       char *endptr;
> @@ -1345,6 +1374,9 @@ int main(int argc, char *argv[])
>               case OPT_KEXEC_FILE_SYSCALL:
>                       /* We already parsed it. Nothing to do. */
>                       break;
> +             case OPT_STATUS:
> +                     do_status = 1;
> +                     break;
>               default:
>                       break;
>               }
> @@ -1355,6 +1387,20 @@ int main(int argc, char *argv[])
>       if (skip_sync)
>               do_sync = 0;
>  
> +     if (do_status) {
> +             if (kexec_flags == 0)
> +                     kexec_flags = KEXEC_ON_CRASH;
> +             do_load = 0;
> +             do_reuse_initrd = 0;
> +             do_unload = 0;
> +             do_load = 0;
> +             do_shutdown = 0;
> +             do_sync = 0;
> +             do_ifdown = 0;
> +             do_exec = 0;
> +             do_load_jump_back_helper = 0;
> +     }
> +
>       if (do_load && (kexec_flags & KEXEC_ON_CRASH) &&
>           !is_crashkernel_mem_reserved()) {
>               die("Memory for crashkernel is not reserved\n"
> @@ -1392,7 +1438,9 @@ int main(int argc, char *argv[])
>               check_reuse_initrd();
>               arch_reuse_initrd();
>       }
> -
> +     if (do_status) {
> +             result = k_status(kexec_flags);
> +     }
>       if (do_unload) {
>               if (do_kexec_file_syscall)
>                       result = kexec_file_unload(kexec_file_flags);
> @@ -1408,7 +1456,7 @@ int main(int argc, char *argv[])
>                                               kexec_flags, entry);
>       }
>       /* Don't shutdown unless there is something to reboot to! */
> -     if ((result == 0) && (do_shutdown || do_exec) && !kexec_loaded()) {
> +     if ((result == 0) && (do_shutdown || do_exec) && 
> !kexec_loaded(KEXEC_LOADED_PATH)) {
>               die("Nothing has been loaded!\n");
>       }
>       if ((result == 0) && do_shutdown) {
> diff --git a/kexec/kexec.h b/kexec/kexec.h
> index 9194f1c..2b06f59 100644
> --- a/kexec/kexec.h
> +++ b/kexec/kexec.h
> @@ -219,6 +219,7 @@ extern int file_types;
>  #define OPT_TYPE             't'
>  #define OPT_PANIC            'p'
>  #define OPT_KEXEC_FILE_SYSCALL       's'
> +#define OPT_STATUS           'S'
>  #define OPT_MEM_MIN             256
>  #define OPT_MEM_MAX             257
>  #define OPT_REUSE_INITRD     258
> @@ -245,8 +246,9 @@ extern int file_types;
>       { "reuseinitrd",        0, 0, OPT_REUSE_INITRD }, \
>       { "kexec-file-syscall", 0, 0, OPT_KEXEC_FILE_SYSCALL }, \
>       { "debug",              0, 0, OPT_DEBUG }, \
> +     { "status",             0, 0, OPT_STATUS }, \
>  
> -#define KEXEC_OPT_STR "h?vdfxyluet:ps"
> +#define KEXEC_OPT_STR "h?vdfxyluet:psS"
>  
>  extern void dbgprint_mem_range(const char *prefix, struct memory_range *mr, 
> int nr_mr);
>  extern void die(const char *fmt, ...)
> @@ -311,5 +313,6 @@ int xen_present(void);
>  int xen_kexec_load(struct kexec_info *info);
>  int xen_kexec_unload(uint64_t kexec_flags);
>  void xen_kexec_exec(void);
> +int xen_kexec_status(uint64_t kexec_flags);
>  
>  #endif /* KEXEC_H */
> -- 
> 2.7.4
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/kexec

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