[ppc64 help] Convert breakpoint's into addresses

[ppc64 help] Convert breakpoint's into addresses

[Andrew Cagney]

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Hello,

I think the ppc64 ELF ABI is officially wierd.

For "main" the minimal symbol table contains two symbols vis:

	main: points at descriptor in .opd sectoin
	.main: points at main's code entry point

Consequently, given only a minimal symbol table, GDB, when given:

	(gdb) break main

will try to insert the breakpoint in the descriptor, and not the 
function.  Trying to enter:

	(gdb) break .main

gets you no where (syntax error :-/)

Adding to the fun, GCC's debug info contains the symbol "main" which 
points at the code address (and not the descriptor) and consequently 
debugging with symbols works.  Yes, this means that "main" has two 
different values, arrrghghgh!!

Attatched is a hack to breakpoint.c that applies "convert from func ptr 
addr" to any address.  This causing the breakpoint code to convert 
"main" into ".main" and hence work.

I don't know if its a right fix, good fix, or of any other alternative 
fix.  However it does work ...

help!

Andrew

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2003-09-17  Andrew Cagney  <cagney@redhat.com>

	* breakpoint.c (set_raw_breakpoint): Apply
	CONVERT_FROM_FUNC_PTR_ADDR to the breakpoint address.
	(breakpoint_re_set_one): Ditto.

Index: breakpoint.c
===================================================================
RCS file: /cvs/src/src/gdb/breakpoint.c,v
retrieving revision 1.129
diff -u -r1.129 breakpoint.c
--- breakpoint.c	14 Sep 2003 16:32:12 -0000	1.129
+++ breakpoint.c	19 Sep 2003 15:43:52 -0000
@@ -3866,7 +3866,7 @@
 
   b = (struct breakpoint *) xmalloc (sizeof (struct breakpoint));
   memset (b, 0, sizeof (*b));
-  b->address = sal.pc;
+  b->address = CONVERT_FROM_FUNC_PTR_ADDR (sal.pc);
   if (sal.symtab == NULL)
     b->source_file = NULL;
   else
@@ -6838,7 +6838,7 @@
 		  savestring (sals.sals[i].symtab->filename,
 			      strlen (sals.sals[i].symtab->filename));
 	      b->line_number = sals.sals[i].line;
-	      b->address = sals.sals[i].pc;
+	      b->address = CONVERT_FROM_FUNC_PTR_ADDR (sals.sals[i].pc);
 
 	      /* Used to check for duplicates here, but that can
 	         cause trouble, as it doesn't check for disabled

Re: [ppc64 help] Convert breakpoint's into addresses

[Kevin Buettner]

On Sep 19,  3:40pm, Andrew Cagney wrote:

> I think the ppc64 ELF ABI is officially wierd.
> 
> For "main" the minimal symbol table contains two symbols vis:
> 
> 	main: points at descriptor in .opd sectoin
> 	.main: points at main's code entry point
> 
> Consequently, given only a minimal symbol table, GDB, when given:
> 
> 	(gdb) break main
> 
> will try to insert the breakpoint in the descriptor, and not the 
> function.  Trying to enter:
> 
> 	(gdb) break .main
> 
> gets you no where (syntax error :-/)
> 
> Adding to the fun, GCC's debug info contains the symbol "main" which 
> points at the code address (and not the descriptor) and consequently 
> debugging with symbols works.  Yes, this means that "main" has two 
> different values, arrrghghgh!!

Yuck.  Is gcc simply broken or is there a good reason to do things this
way?

> Attatched is a hack to breakpoint.c that applies "convert from func ptr 
> addr" to any address.  This causing the breakpoint code to convert 
> "main" into ".main" and hence work.
> 
> I don't know if its a right fix, good fix, or of any other alternative 
> fix.  However it does work ...

> help!
> 
> 2003-09-17  Andrew Cagney  <cagney@redhat.com>
> 
> 	* breakpoint.c (set_raw_breakpoint): Apply
> 	CONVERT_FROM_FUNC_PTR_ADDR to the breakpoint address.
> 	(breakpoint_re_set_one): Ditto.

I can't think of anything better.  If this goes in, I suggest adding
a nice fat comment explaining what's going on...

Kevin