Re: [Xen-devel] [PATCH] common/symbols: Drop '+0/<len>' when printing function pointer symbols.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2013-10-04 at 11:02 +0100, Andrew Cooper wrote:
> Introduce print_function() with the same semantics as print_symbol().  The
> underlying __print_symbol() now takes an extra boolean indicating whether we
> are expecting to print a function pointer.   In the case that we are expecting
> a function pointer, and the offset is 0, drop the offset and length.
> 
> The requirement for offset being 0 is for the (hopefully never, but we really
> want to know if it does happen) case where a Xen function pointer is not
> actually pointing at the start of a function.
> 
> The relevent print_symbol() functions are updated to print_function()

I've been yearning after the Linux printk %pS and %pF extensions for a
while now...

> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> CC: Keir Fraser <keir@xxxxxxx>
> CC: Jan Beulich <jbeulich@xxxxxxxx>
> ---
>  xen/arch/x86/irq.c        |    2 +-
>  xen/arch/x86/time.c       |    4 ++--
>  xen/common/symbols.c      |    7 +++++--
>  xen/common/timer.c        |    2 +-
>  xen/include/xen/symbols.h |   16 +++++++++++++---
>  5 files changed, 22 insertions(+), 9 deletions(-)
> 
> diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
> index c61cc46..c349dd2 100644
> --- a/xen/arch/x86/irq.c
> +++ b/xen/arch/x86/irq.c
> @@ -2280,7 +2280,7 @@ static void dump_irqs(unsigned char key)
>              printk("\n");
>          }
>          else if ( desc->action )
> -            print_symbol("%s\n", (unsigned long)desc->action->handler);
> +            print_function("%s()\n", (unsigned long)desc->action->handler);
>          else
>              printk("mapped, unbound\n");
>  
> diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c
> index c1bbd50..d857650 100644
> --- a/xen/arch/x86/time.c
> +++ b/xen/arch/x86/time.c
> @@ -1475,8 +1475,8 @@ static int 
> _disable_pit_irq(void(*hpet_broadcast_setup)(void))
>          {
>              if ( xen_cpuidle > 0 )
>              {
> -                print_symbol("%s() failed, turning to PIT broadcast\n",
> -                             (unsigned long)hpet_broadcast_setup);
> +                print_function("%s() failed, turning to PIT broadcast\n",
> +                               (unsigned long)hpet_broadcast_setup);
>                  return -1;
>              }
>              ret = 0;
> diff --git a/xen/common/symbols.c b/xen/common/symbols.c
> index 83b2b58..9dcaaba 100644
> --- a/xen/common/symbols.c
> +++ b/xen/common/symbols.c
> @@ -150,7 +150,7 @@ const char *symbols_lookup(unsigned long addr,
>  }
>  
>  /* Replace "%s" in format with address, or returns -errno. */
> -void __print_symbol(const char *fmt, unsigned long address)
> +void __print_symbol(const char *fmt, unsigned long address, bool_t fnptr)
>  {
>      const char *name;
>      unsigned long offset, size, flags;
> @@ -168,7 +168,10 @@ void __print_symbol(const char *fmt, unsigned long 
> address)
>      if (!name)
>          snprintf(buffer, BUFFER_SIZE, "???");
>      else
> -        snprintf(buffer, BUFFER_SIZE, "%s+%#lx/%#lx", name, offset, size);
> +        if ( fnptr && offset == 0 )
> +            snprintf(buffer, BUFFER_SIZE, "%s", name);
> +        else
> +            snprintf(buffer, BUFFER_SIZE, "%s+%#lx/%#lx", name, offset, 
> size);
>  
>      printk(fmt, buffer);
>  
> diff --git a/xen/common/timer.c b/xen/common/timer.c
> index 9ed74e9..2008aa3 100644
> --- a/xen/common/timer.c
> +++ b/xen/common/timer.c
> @@ -513,7 +513,7 @@ static void dump_timer(struct timer *t, s_time_t now)
>  {
>      printk("  ex=%8"PRId64"us timer=%p cb=%p(%p)",
>             (t->expires - now) / 1000, t, t->function, t->data);
> -    print_symbol(" %s\n", (unsigned long)t->function);
> +    print_function(" %s()\n", (unsigned long)t->function);
>  }
>  
>  static void dump_timerq(unsigned char key)
> diff --git a/xen/include/xen/symbols.h b/xen/include/xen/symbols.h
> index 37cf6bf..866231e 100644
> --- a/xen/include/xen/symbols.h
> +++ b/xen/include/xen/symbols.h
> @@ -11,8 +11,12 @@ const char *symbols_lookup(unsigned long addr,
>                             unsigned long *offset,
>                             char *namebuf);
>  
> -/* Replace "%s" in format with address, if found */
> -void __print_symbol(const char *fmt, unsigned long address);
> +/*
> + * Replace "%s" in format with address, if found.  'fnptr' indicates a
> + * function pointer address is expected, in which case the '+0/<length>' is
> + * dropped for clarity.
> + */
> +void __print_symbol(const char *fmt, unsigned long address, bool_t fnptr);
>  
>  /* This macro allows us to keep printk typechecking */
>  static void __check_printsym_format(const char *fmt, ...)
> @@ -31,7 +35,13 @@ static void __check_printsym_format(const char *fmt, ...)
>  #define print_symbol(fmt, addr)                      \
>  do {                                         \
>       __check_printsym_format(fmt, "");       \
> -     __print_symbol(fmt, addr);              \
> +     __print_symbol(fmt, addr, 0);           \
> +} while(0)
> +
> +#define print_function(fmt, addr)            \
> +do {                                         \
> +     __check_printsym_format(fmt, "");       \
> +     __print_symbol(fmt, addr, 1);           \
>  } while(0)
>  
>  #endif /*_XEN_SYMBOLS_H*/



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