[PATCH] sym.c: fix module_kallsyms_on_each_symbol not exported

[William Cohen]

Hi,
I plan on taking a look at this patch Thursday.  Do you have a pointer to the environment (distribution, specific kernel) where systemtap failed WITHOUT this patch? Thanks,

-Will
On 6/18/24 12:52, tonyj@suse.de wrote:
> module_kallsyms_on_each_symbol has never been exported (as noted by
> 33fae2d0107f ("This one seems simply like a non-export").  
> 
> If kallsyms_on_each_symbol is exported (a revert of upstream in our 
> SLES case) then '!defined(STAPCONF_KALLSYMS_ON_EACH_SYMBOL_EXPORTED)' 
> is false and the local definition of module_kallsyms_on_each_symbol is 
> skipped.
> 
> This results in:
> ERROR: modpost: "module_kallsyms_on_each_symbol" undefined!
> 
> Fixes: 33fae2d0107fb6166b4eac3fdffd277829849ab0
> Signed-off-by: Tony Jones <tonyj@suse.de>
> 
> diff --git a/runtime/sym.c b/runtime/sym.c
> index 23dd3be30..102257965 100644
> --- a/runtime/sym.c
> +++ b/runtime/sym.c
> @@ -1180,7 +1180,8 @@ unsigned long kallsyms_lookup_name (const char *name)
>  }
>  #endif
>  
> -#if defined(STAPCONF_KALLSYMS_ON_EACH_SYMBOL) && !defined(STAPCONF_KALLSYMS_ON_EACH_SYMBOL_EXPORTED)
> +#if defined(STAPCONF_KALLSYMS_ON_EACH_SYMBOL)
> +#if !defined(STAPCONF_KALLSYMS_ON_EACH_SYMBOL_EXPORTED)
>  #ifndef KALLSYMS_H_INCLUDED
>  #include <linux/kallsyms.h>
>  #endif
> @@ -1209,11 +1210,12 @@ int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *,
>          _stp_error("BUG: attempting to use unavailable kallsyms_on_each_symbol!!\n");
>          return 0;
>  }
> +#endif // !defined(STAPCONF_KALLSYMS_ON_EACH_SYMBOL_EXPORTED)
>  
> +// XXX module_kallsyms_on_each_symbol has never been exported
>  #if LINUX_VERSION_CODE >= KERNEL_VERSION(5,12,0)
>  typedef typeof(&module_kallsyms_on_each_symbol) module_kallsyms_on_each_symbol_fn;
>  
> -// XXX Will be linked in place of the kernel's module_kallsyms_on_each_symbol:
>  #if defined(STAPCONF_KALLSYMS_6_4)
>  int module_kallsyms_on_each_symbol(const char *modname,
>                                     int (*fn)(void *, const char *,
>