Re: [Xen-devel] [PATCH v3 17/23] xsplice: Print dependency and payloads build_id in the keyhandler.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.02.16 at 22:54, <konrad.wilk@xxxxxxxxxx> wrote:
> On Wed, Feb 17, 2016 at 04:10:12AM -0700, Jan Beulich wrote:
>> >>> On 16.02.16 at 21:20, <andrew.cooper3@xxxxxxxxxx> wrote:
>> > On 12/02/16 18:05, Konrad Rzeszutek Wilk wrote:
>> >> +static void xsplice_print_build_id(char *id, unsigned int len)
>> >> +{
>> >> +    unsigned int i;
>> >> +
>> >> +    if ( !len )
>> >> +        return;
>> >> +
>> >> +    for ( i = 0; i < len; i++ )
>> >> +    {
>> >> +        uint8_t c = id[i];
>> >> +        printk("%02x", c);
>> > 
>> > What about the already existing %*ph custom format?  If the spaces are a
>> > problem we could introduce %*phN from Linux which has no spaces.
>> > 
>> > The advantage of this is that it is a single call to printk, rather than
>> > many, and avoids the ability for a different cpu to interleave in the
>> > middle of a line.
>> 
>> I don't think this ability exists anymore after we've switched to
>> per-CPU there. Which isn't to say, though, that I wouldn't also
>> like to see this be just a single printk().
> 
> Would this work for folks:

Well, while it looks like it would work, it doesn't really follow Andrew's
suggestion.

Jan

> commit e1905ecf7034635f2a82cd2bbc4f5ff03ee957b0
> Author: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Date:   Wed Feb 24 15:06:15 2016 -0500
> 
>     xsplice: Print build_id in keyhandler and on bootup.
>     
>     As it should be an useful debug mechanism.
>     
>     Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> 
> diff --git a/xen/common/xsplice.c b/xen/common/xsplice.c
> index da26b58..b15a2de 100644
> --- a/xen/common/xsplice.c
> +++ b/xen/common/xsplice.c
> @@ -13,6 +13,7 @@
>  #include <xen/smp.h>
>  #include <xen/softirq.h>
>  #include <xen/spinlock.h>
> +#include <xen/version.h>
>  #include <xen/vmap.h>
>  #include <xen/wait.h>
>  #include <xen/xsplice_elf.h>
> @@ -1079,10 +1080,33 @@ static const char *state2str(uint32_t state)
>      return names[state];
>  }
>  
> +static void xsplice_print_build_id(const char *hdr, const char *id,
> +                                   unsigned int len)
> +{
> +    unsigned int i;
> +
> +    if ( !len )
> +        return;
> +
> +    /* Each byte is two ASCII characters. */
> +    if ( len*2 + 1 > sizeof(keyhandler_scratch) )
> +        return;
> +
> +    memset(keyhandler_scratch, 0, len * 2 + 1);
> +    for ( i = 0; i < len; i++ )
> +        snprintf(&keyhandler_scratch[i * 2], 3, "%02x", (uint8_t)id[i]);
> +
> +    printk("%s%s\n", hdr, keyhandler_scratch);
> +}
> +
>  static void xsplice_printall(unsigned char key)
>  {
>      struct payload *data;
> -    unsigned int i;
> +    char *binary_id = NULL;
> +    unsigned int len = 0, i;
> +
> +    if ( !xen_build_id(&binary_id, &len) )
> +        xsplice_print_build_id("build-id: ", binary_id, len);
>  
>      spin_lock_recursive(&payload_lock);
>  
> @@ -1106,8 +1130,14 @@ static void xsplice_printall(unsigned char key)
>  
>  static int __init xsplice_init(void)
>  {
> +    char *binary_id = NULL;
> +    unsigned int len = 0;
>      BUILD_BUG_ON( sizeof(struct xsplice_patch_func) != 64 );
>  
> +    if ( !xen_build_id(&binary_id, &len) )
> +        xsplice_print_build_id("build-id: ", binary_id, len);
> +
> +    xsplice_print_build_id("Hypervisor build-id: ", binary_id, len);
>      register_keyhandler('x', xsplice_printall, "print xsplicing info", 1);
>      return 0;
>  }
>> 
>> Jan
>> 




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