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Calling functions via function descriptors saved with cast needed for ia
|
From: |
Piet/Pete Delaney |
|
Subject: |
Calling functions via function descriptors saved with cast needed for ia64 code. Illegal Instruction. |
|
Date: |
Thu, 3 Jan 2002 00:18:33 -0800 |
|
User-agent: |
Mutt/1.3.23i |
On Wed, Jan 02, 2002 at 09:46:35PM -0800, Piet/Pete Delaney wrote:
With the cast that you (Keith Owens) suggested the assignment code seems
to be fine but the dereference of the pointer causes a illegal instruction
signal.
Unfortunately the problem doesn't occure in the simple example. I suppose it
has to do with linking.
In the lcrash/lkcd case we have a resonable pointer to the function to
disassemble the instructions (via libopcodes.a):
(gdb) where
#0 0x400005801a415000 in ?? ()
[How did I get here?]
#1 0x400000000006d320 in dis_printintaddr (addr=0xe0020000006abae0,
dip=0x600000000001e0c0, flag=0x1) at dis.c:62
#2 0x400000000006da30 in do_dis (value=0xe0020000006abae0, lines=0x1,
ofp=0x20000000004a35b0) at dis.c:141
#3 0x400000000006e3a0 in print_instr_stream (v=0xe0020000006abae0, bcount=0x0,
acount=0x0, flags=0x0, ofp=0x20000000004a35b0) at dis.c:241
#4 0x4000000000054340 in dis_cmd (cmd=0x6000000000255000) at cmd_dis.c:164
#5 0x400000000004ca70 in do_cmd (cmd=0x6000000000255000) at command.c:450
#6 0x400000000004cc40 in process_cmds () at command.c:475
#7 0x4000000000011520 in main (argc=0x1, argv=0x80000fffffffb7c8) at main.c:265
(gdb)
(gdb) print *dip
$2 = {
fprintf_func = 0x400000000006cfb0 <dis_fprintf>, <-- Pointer to
function seems to be ok
stream = 0x20000000004a35b0,
application_data = 0x0,
flavour = bfd_target_elf_flavour,
arch = bfd_arch_ia64,
mach = 0x2b,
endian = BFD_ENDIAN_LITTLE,
symbols = 0x0,
num_symbols = 0x0,
flags = 0x0,
private_data = 0x0,
read_memory_func = 0x400000000006d0c0 <getidmem>,
memory_error_func = 0,
print_address_func = 0x400000000006d7f0 <dis_printaddr>,
symbol_at_address_func = 0x400000000006d880 <dis_getsym>,
buffer = 0x0,
buffer_vma = 0x0,
buffer_length = 0x0,
bytes_per_line = 0x0,
bytes_per_chunk = 0x0,
display_endian = BFD_ENDIAN_LITTLE,
octets_per_byte = 0x0,
insn_info_valid = 0x0,
branch_delay_insns = 0x0,
data_size = 0x0,
insn_type = dis_noninsn,
target = 0x0,
target2 = 0x0,
disassembler_options = 0x0
}
(gdb)
When executing:
47 /*
48 * dis_printintaddr()
49 */
50 static void
51 dis_printintaddr(bfd_vma addr, struct disassemble_info *dip, int flag)
52 {
53 int offset = 0;
54 syment_t *sp;
55
56 if ((sp = kl_lkup_symaddr(addr))) {
57 offset = addr - sp->s_addr;
58 }
59
60 /* Print out address
61 */
62 dip->fprintf_func(dip->stream, "0x%llx", addr);
Illegal instruction hit in asm code
Dump of assembler code from 0x400000000006d2b0 to 0x400000000006d3b0:
0x400000000006d2b0 <dis_printintaddr+224>: [MMI] adds r14=-456,r38;;
Line 62 above....
0x400000000006d2b1 <dis_printintaddr+225>: ld8 r15=[r14]
0x400000000006d2b2 <dis_printintaddr+226>: adds r14=-456,r38;;
0x400000000006d2c0 <dis_printintaddr+240>: [MMI] ld8 r14=[r14];;
0x400000000006d2c1 <dis_printintaddr+241>: adds r14=8,r14
0x400000000006d2c2 <dis_printintaddr+242>: nop.i 0x0
0x400000000006d2d0 <dis_printintaddr+256>: [MMI] ld8 r16=[r15];;
0x400000000006d2d1 <dis_printintaddr+257>: ld8 r39=[r14]
0x400000000006d2d2 <dis_printintaddr+258>: addl r14=1848,r1;;
0x400000000006d2e0 <dis_printintaddr+272>: [MFI] ld8 r40=[r14]
0x400000000006d2e1 <dis_printintaddr+273>: nop.f 0x0
0x400000000006d2e2 <dis_printintaddr+274>: adds r14=-464,r38;;
0x400000000006d2f0 <dis_printintaddr+288>: [MFI] ld8 r41=[r14]
0x400000000006d2f1 <dis_printintaddr+289>: nop.f 0x0
0x400000000006d2f2 <dis_printintaddr+290>: mov r35=r1
0x400000000006d300 <dis_printintaddr+304>: [MFI] ld8 r15=[r16]
0x400000000006d301 <dis_printintaddr+305>: nop.f 0x0
0x400000000006d302 <dis_printintaddr+306>: adds r14=8,r16;;
0x400000000006d310 <dis_printintaddr+320>: [MIB] ld8 r1=[r14]
0x400000000006d311 <dis_printintaddr+321>: mov b6=r15
0x400000000006d312 <dis_printintaddr+322>: br.call.sptk.many
b0=b6;; Get an Illegal instruction next
Registers at a breakpoint at the br.call.sptk.many b0=b6;; are shown below.
Executing the br.call.sptk.many results in a SIGILL with a pc of
0x400005801a415000.
The value in registers being used are:
(gdb) info register b0
Return Address
b0 0x400000000006d320 0x400000000006d320
(gdb) info register b6
Should be dis_fprintf
b6 0x410005801a415000 0x410005801a415000
(gdb)
I'm still learning the asm code for ia64 and don't yet understand how
we single stepped to 0x400005801a415000 using these registers. Perhaps
gdb doesn't single step calls thru pointers corectly. Anyone have a clue?
I suspect another cast is needed when the function descriptor is used. Sigh!
-piet
(gdb) info registers
r0 0x0 0x0
r1 0x8cfc678220420030 0x8cfc678220420030
r2 0x80000fffffffb320 0x80000fffffffb320
r3 0x80000fffffffb710 0x80000fffffffb710
r4 0x0 0x0
r5 0x0 0x0
r6 0x0 0x0
r7 0x0 0x0
r8 0x60000000000afd30 0x60000000000afd30
r9 0x600000000001e7e0 0x600000000001e7e0
r10 0x0 0x0
r11 0x600000000000a580 0x600000000000a580
r12 0x80000fffffffb360 0x80000fffffffb360
r13 0x0 0x0
r14 0x400000000006cfb8 0x400000000006cfb8
r15 0x410005801a415000 0x410005801a415000
r16 0x400000000006cfb0 0x400000000006cfb0
r17 0x80000fffffffb330 0x80000fffffffb330
r18 0x80000fffffffb330 0x80000fffffffb330
r19 0x6000000000255000 0x6000000000255000
r20 0x0 0x0
r21 0x4000000000008390 0x4000000000008390
r22 0x6000000000253180 0x6000000000253180
r23 0x7ffff000000048ec 0x7ffff000000048ec
r24 0x10 0x10
r25 0x4 0x4
r26 0x60000000002ee678 0x60000000002ee678
r27 0x0 0x0
r28 0x40 0x40
r29 0x0 0x0
r30 0x3 0x3
r31 0x6000 0x6000
r32 0xe0020000006abae0 0xe0020000006abae0
r33 0x600000000001e0c0 0x600000000001e0c0
r34 0x1 0x1
r35 0x600000000000a140 0x600000000000a140
r36 0x400000000006da30 0x400000000006da30
r37 0xc00000000000038a 0xc00000000000038a
r38 0x80000fffffffb540 0x80000fffffffb540
r39 0x20000000004a35b0 0x20000000004a35b0
r40 0x40000000001b60d0 0x40000000001b60d0
r41 0xe0020000006abae0 0xe0020000006abae0
r42 0xc00000000000038b 0xc00000000000038b
r43 0x0 0x0
r44 0x0 0x0
r45 0x0 0x0
r46 0x0 0x0
r47 0x0 0x0
r48 0x0 0x0
r49 0x0 0x0
r50 0x0 0x0
r51 0x0 0x0
r52 0x0 0x0
r53 0x0 0x0
r54 0x0 0x0
r55 0x0 0x0
r56 0x0 0x0
r57 0x0 0x0
r58 0x0 0x0
r59 0x0 0x0
r60 0x0 0x0
r61 0x0 0x0
r62 0x0 0x0
r63 0x0 0x0
r64 0x0 0x0
r65 0x0 0x0
r66 0x0 0x0
r67 0x0 0x0
r68 0x0 0x0
r69 0x0 0x0
r70 0x0 0x0
r71 0x0 0x0
r72 0x0 0x0
r73 0x0 0x0
r74 0x0 0x0
r75 0x0 0x0
r76 0x0 0x0
r77 0x0 0x0
r78 0x0 0x0
r79 0x0 0x0
r80 0x0 0x0
r81 0x0 0x0
r82 0x0 0x0
r83 0x0 0x0
r84 0x0 0x0
r85 0x0 0x0
r86 0x0 0x0
r87 0x0 0x0
r88 0x0 0x0
r89 0x0 0x0
r90 0x0 0x0
r91 0x0 0x0
r92 0x0 0x0
r93 0x0 0x0
r94 0x0 0x0
r95 0x0 0x0
r96 0x0 0x0
r97 0x0 0x0
r98 0x0 0x0
r99 0x0 0x0
r100 0x0 0x0
r101 0x0 0x0
r102 0x0 0x0
r103 0x0 0x0
r104 0x0 0x0
r105 0x0 0x0
r106 0x0 0x0
r107 0x0 0x0
r108 0x0 0x0
r109 0x0 0x0
r110 0x0 0x0
r111 0x0 0x0
r112 0x0 0x0
r113 0x0 0x0
r114 0x0 0x0
r115 0x0 0x0
r116 0x0 0x0
r117 0x0 0x0
r118 0x0 0x0
r119 0x0 0x0
r120 0x0 0x0
r121 0x0 0x0
r122 0x0 0x0
r123 0x0 0x0
r124 0x0 0x0
r125 0x0 0x0
r126 0x0 0x0
r127 0x0 0x0
p0 0x1 0x1
p1 0x0 0x0
p2 0x0 0x0
p3 0x0 0x0
p4 0x0 0x0
p5 0x0 0x0
p6 0x0 0x0
p7 0x1 0x1
p8 0x0 0x0
p9 0x1 0x1
p10 0x1 0x1
p11 0x0 0x0
p12 0x0 0x0
p13 0x1 0x1
p14 0x1 0x1
p15 0x0 0x0
p16 0x0 0x0
p17 0x0 0x0
p18 0x0 0x0
p19 0x0 0x0
p20 0x0 0x0
p21 0x0 0x0
p22 0x0 0x0
p23 0x0 0x0
p24 0x0 0x0
p25 0x0 0x0
p26 0x0 0x0
p27 0x0 0x0
p28 0x0 0x0
p29 0x0 0x0
p30 0x0 0x0
p31 0x0 0x0
p32 0x0 0x0
p33 0x0 0x0
p34 0x0 0x0
p35 0x0 0x0
p36 0x0 0x0
p37 0x0 0x0
p38 0x0 0x0
p39 0x0 0x0
p40 0x0 0x0
p41 0x0 0x0
p42 0x0 0x0
p43 0x0 0x0
p44 0x0 0x0
p45 0x0 0x0
p46 0x0 0x0
p47 0x0 0x0
p48 0x0 0x0
p49 0x0 0x0
p50 0x0 0x0
p51 0x0 0x0
p52 0x0 0x0
p53 0x0 0x0
p54 0x0 0x0
p55 0x0 0x0
p56 0x0 0x0
p57 0x0 0x0
p58 0x0 0x0
p59 0x0 0x0
p60 0x0 0x0
p61 0x0 0x0
p62 0x0 0x0
p63 0x0 0x0
b0 0x400000000006d240 0x400000000006d240
b1 0x0 0x0
b2 0x0 0x0
b3 0x0 0x0
b4 0x0 0x0
b5 0x0 0x0
b6 0x410005801a415000 0x410005801a415000
b7 0x0 0x0
vfp 0x80000fffffffb360 0x80000fffffffb360
vrap 0x0 0x0
pr 0x6681 0x6681
ip 0x400000000006d312 0x400000000006d312
psr 0x40000000010 0x40000000010
cfm 0x38b 0x38b
kr0 0x0 0x0
kr1 0x0 0x0
kr2 0x0 0x0
kr3 0x0 0x0
kr4 0x0 0x0
kr5 0x0 0x0
kr6 0x0 0x0
kr7 0x0 0x0
rsc 0xf 0xf
bsp 0x80000fff80000178 0x80000fff80000178
bspstore 0x80000fff800000c8 0x80000fff800000c8
rnat 0x0 0x0
fcr 0x0 0x0
eflag 0x0 0x0
csd 0x0 0x0
ssd 0x0 0x0
cflg 0x0 0x0
fsr 0x0 0x0
fir 0x0 0x0
fdr 0x0 0x0
ccv 0x0 0x0
unat 0x0 0x0
fpsr 0x9804c8a70033f 0x9804c8a70033f
itc 0x0 0x0
pfs 0xc00000000000038b 0xc00000000000038b
lc 0x0 0x0
ec 0x0 0x0
nat0 0x0 0x0
nat1 0x0 0x0
nat2 0x0 0x0
nat3 0x0 0x0
nat4 0x0 0x0
nat5 0x0 0x0
nat6 0x0 0x0
nat7 0x0 0x0
nat8 0x0 0x0
nat9 0x0 0x0
nat10 0x0 0x0
nat11 0x0 0x0
nat12 0x0 0x0
nat13 0x0 0x0
nat14 0x0 0x0
nat15 0x0 0x0
nat16 0x0 0x0
nat17 0x0 0x0
nat18 0x0 0x0
nat19 0x0 0x0
nat20 0x0 0x0
nat21 0x0 0x0
nat22 0x0 0x0
nat23 0x0 0x0
nat24 0x0 0x0
nat25 0x0 0x0
nat26 0x0 0x0
nat27 0x0 0x0
nat28 0x0 0x0
nat29 0x0 0x0
nat30 0x0 0x0
nat31 0x0 0x0
nat32 0x0 0x0
nat33 0x0 0x0
nat34 0x0 0x0
nat35 0x0 0x0
nat36 0x0 0x0
nat37 0x0 0x0
nat38 0x0 0x0
nat39 0x0 0x0
nat40 0x0 0x0
nat41 0x0 0x0
nat42 0x0 0x0
nat43 0x0 0x0
nat44 0x0 0x0
nat45 0x0 0x0
nat46 0x0 0x0
nat47 0x0 0x0
nat48 0x0 0x0
nat49 0x0 0x0
nat50 0x0 0x0
nat51 0x0 0x0
nat52 0x0 0x0
nat53 0x0 0x0
nat54 0x0 0x0
nat55 0x0 0x0
nat56 0x0 0x0
nat57 0x0 0x0
nat58 0x0 0x0
nat59 0x0 0x0
nat60 0x0 0x0
nat61 0x0 0x0
nat62 0x0 0x0
nat63 0x0 0x0
nat64 0x0 0x0
nat65 0x0 0x0
nat66 0x0 0x0
nat67 0x0 0x0
nat68 0x0 0x0
nat69 0x0 0x0
nat70 0x0 0x0
nat71 0x0 0x0
nat72 0x0 0x0
nat73 0x0 0x0
nat74 0x0 0x0
nat75 0x0 0x0
nat76 0x0 0x0
nat77 0x0 0x0
nat78 0x0 0x0
nat79 0x0 0x0
nat80 0x0 0x0
nat81 0x0 0x0
nat82 0x0 0x0
nat83 0x0 0x0
nat84 0x0 0x0
nat85 0x0 0x0
nat86 0x0 0x0
nat87 0x0 0x0
nat88 0x0 0x0
nat89 0x0 0x0
nat90 0x0 0x0
nat91 0x0 0x0
nat92 0x0 0x0
nat93 0x0 0x0
nat94 0x0 0x0
nat95 0x0 0x0
nat96 0x0 0x0
nat97 0x0 0x0
nat98 0x0 0x0
nat99 0x0 0x0
nat100 0x0 0x0
nat101 0x0 0x0
nat102 0x0 0x0
nat103 0x0 0x0
nat104 0x0 0x0
nat105 0x0 0x0
nat106 0x0 0x0
nat107 0x0 0x0
nat108 0x0 0x0
nat109 0x0 0x0
nat110 0x0 0x0
nat111 0x0 0x0
nat112 0x0 0x0
nat113 0x0 0x0
nat114 0x0 0x0
nat115 0x0 0x0
nat116 0x0 0x0
nat117 0x0 0x0
nat118 0x0 0x0
nat119 0x0 0x0
nat120 0x0 0x0
nat121 0x0 0x0
nat122 0x0 0x0
nat123 0x0 0x0
nat124 0x0 0x0
nat125 0x0 0x0
nat126 0x0 0x0
nat127 0x0 0x0
(gdb)
> SUMMARY:
>
> Keith Owens just pointed out that ia64 function descriptor assignments
> MUST be cast:
>
> pointer = ((unsigned long *)(&my_printf))[0])
>
> howerver it appears that other platforms MUST NOT be cast.
>
> I was wondering if that a good idea. It seems it might require hacking
> a lot of existing code.
>
> Why is this necessary for just ia64?
>
> I've used pointers to functions a lot in the past and I don't recall
> ever haveing a problem like this.
>
> See details below...
>
> -piet
>
> On Thu, Jan 03, 2002 at 02:30:04PM +1100, Keith Owens wrote:
> > On Wed, 2 Jan 2002 16:27:14 -0800,
> > Piet/Pete Delaney <address@hidden> wrote:
> > >#include <stdio.h>
> > >
> > >
> > >typedef struct disassemble_info {
> > > void (*fprintf_func)();
> > >} disassemble_info_t;
> > >
> > >disassemble_info_t disinfo;
> > >
> > >void my_printf(void)
> > >{
> > > (void) printf("Hello World\n");
> > >}
> > >
> > >main(void)
> > >{
> > > disinfo.fprintf_func = my_printf;
> > > printf("my_printf is at 0x%llx.\n", my_printf);
> > > printf("disinfo is at 0x%llx.\n", &disinfo);
> > > disinfo.fprintf_func();
> > >}
> >
> > You are printing the address of the ia64 function descriptor, not the
> > function itself.
> >
> > printf("&my_printf is at 0x%llx.\n", &my_printf);
> > printf("my_printf is at 0x%llx.\n", ((unsigned long *)(&my_printf))[0]);
> >
> > &my_printf is at 0x40000000000009f0.
> > my_printf is at 0x4000000000000690.
> > disinfo is at 0x6000000000000dd8.
> > Hello World
> >
> > (gdb) disassemble my_printf
> > Dump of assembler code for function my_printf:
> > 0x4000000000000690 <my_printf>: [MII] alloc r34=ar.pfs,5,4,0
> > 0x4000000000000691 <my_printf+1>: mov r35=r12
> > 0x4000000000000692 <my_printf+2>: mov r33=b0 >
> > (gdb) disassemble 0x4000000000000690
> > Dump of assembler code for function my_printf:
> > 0x4000000000000690 <my_printf>: [MII] alloc r34=ar.pfs,5,4,0
> > 0x4000000000000691 <my_printf+1>: mov r35=r12
> > 0x4000000000000692 <my_printf+2>: mov r33=b0 > >
>
> Looks like you appear to be right!
>
> I wonder if this is a problem with src backward compatabity for the C compiler
> to make the cast:
>
> ((unsigned long *)(&my_printf))[0])
>
> need for ia64 but not allowed for irix and ia32.
>
> It would/will require #ifdef's or some architecture specific handeling.
> That doesn't seem like a fantastic idea if we can avoid it.
>
>
> In the test below you can see that the casting does in fact 'fix'
> the problem on ia64 but it breaks irix and ia32. ia32 seems a
> bit brooken allready, the upper bits of the address were wrong.
> Perhaps that's 'just' a printf problem due to it being a 32bit arch.
>
> I wonder what the 64 bit SPARC linux port does. I only have a 32 bit
> SPARC linux at home.
>
> Why does ia64 require this casting?
>
> -piet
>
>
> ------------------------------------------------------------------
> #include <stdio.h>
>
>
> typedef struct disassemble_info {
> void (*fprintf_func)();
> } disassemble_info_t;
>
> disassemble_info_t disinfo;
>
> void my_printf(void)
> {
> (void) printf("Hello World\n");
> }
>
> main(void)
> {
> disinfo.fprintf_func = my_printf;
> printf("my_printf is at 0x%llx.\n", my_printf);
> printf("&my_printf is at 0x%llx.\n", &my_printf);
> printf("&my_printf[0] is at 0x%llx.\n", ((unsigned long
> *)(&my_printf))[0]);
> printf("disinfo is at 0x%llx.\n", &disinfo);
> disinfo.fprintf_func();
> }
> ------------------------------------------------------------------
>
>
> ------------------------------------------------------------------
> irix
> ------------------------------------------------------------------
> 268 piet1 20:43 /tmp> gcc test.c
> 269 piet1 20:43 /tmp> gdb a.out
> GNU gdb 5.0
> Copyright 2000 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB. Type "show warranty" for details.
> This GDB was configured as "mips-sgi-irix6.2"...
> (gdb) run
> Starting program: /tmp/a.out
> my_printf is at 0x10000fd0.
> &my_printf is at 0x10000fd0.
> &my_printf[0] is at 0x27bdffd0. <<-- casting breaks
> irix ports
> disinfo is at 0x100143e0.
> Hello World
>
> Program exited with code 014.
> Current language: auto; currently asm
> (gdb) disassemble my_printf
> Dump of assembler code for function my_printf:
> 0x10000fd0 <my_printf>: addiu $sp,$sp,-48
> 0x10000fd4 <my_printf+4>: sd $ra,32($sp)
> 0x10000fd8 <my_printf+8>: sd $s8,24($sp)
> 0x10000fdc <my_printf+12>: sd $gp,16($sp)
> 0x10000fe0 <my_printf+16>: move $s8,$sp
> 0x10000fe4 <my_printf+20>: lui $at,0x2
> 0x10000fe8 <my_printf+24>: addiu $at,$at,-19696
> 0x10000fec <my_printf+28>: daddu $gp,$at,$t9
> 0x10000ff0 <my_printf+32>: lw $a0,-32720($gp)
> 0x10000ff4 <my_printf+36>: daddiu $a0,$a0,16504
> 0x10000ff8 <my_printf+40>: lw $t9,-32692($gp)
> 0x10000ffc <my_printf+44>: jalr $t9
> 0x10001000 <my_printf+48>: nop
> 0x10001004 <my_printf+52>: move $sp,$s8
> 0x10001008 <my_printf+56>: ld $ra,32($sp)
> 0x1000100c <my_printf+60>: ld $s8,24($sp)
> 0x10001010 <my_printf+64>: ld $gp,16($sp)
> 0x10001014 <my_printf+68>: addiu $sp,$sp,48
> 0x10001018 <my_printf+72>: jr $ra
> 0x1000101c <my_printf+76>: nop
> End of assembler dump.
> (gdb)
> ------------------------------------------------------------------
>
>
> ------------------------------------------------------------------
> ia32 linux
> ------------------------------------------------------------------
> 296 piet2 14:34 ~/src> gcc test.c
> 297 piet2 14:34 ~/src> gdb a.out
> GNU gdb 5.1
> Copyright 2001 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB. Type "show warranty" for details.
> This GDB was configured as "i686-pc-linux-gnu"...
> (gdb) run
> Starting program: /home/piet/src/a.out
> ~piet/.cshrc: Entry
> ~piet/.cshrc: Non Interactive Shell
> ~piet/.cshrc: Not Interactive shlvl: 5
> my_printf is at 0xbffff8e808048460. <<----- ia32 linux high order
> bits are wrong.
> &my_printf is at 0xbffff8e808048460.
> &my_printf[0] is at 0xbffff8e883e58955. <<----- casting breaks
> ia32 linux ports
> disinfo is at 0xbffff8e8080496f4.
> Hello World
>
> Program exited with code 014.
> (gdb) disassemble my_printf
> Dump of assembler code for function my_printf:
> 0x8048460 <my_printf>: push %ebp
> 0x8048461 <my_printf+1>: mov %esp,%ebp
> 0x8048463 <my_printf+3>: sub $0x8,%esp
> 0x8048466 <my_printf+6>: sub $0xc,%esp
> 0x8048469 <my_printf+9>: push $0x8048558
> 0x804846e <my_printf+14>: call 0x804833c <printf>
> 0x8048473 <my_printf+19>: add $0x10,%esp
> 0x8048476 <my_printf+22>: leave
> 0x8048477 <my_printf+23>: ret
> End of assembler dump.
> (gdb)
> ------------------------------------------------------------------
>
>
> ------------------------------------------------------------------
> ia64 linux
> ------------------------------------------------------------------
> 260 monica 20:27 ~/src> gcc test.c
> 261 monica 20:27 ~/src> gdb a.out
> GNU gdb Red Hat Linux 7.x (5.0rh-9)
> Copyright 2001 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB. Type "show warranty" for details.
> This GDB was configured as "ia64-redhat-linux"...
> (gdb) run
> Starting program: /home/piet/src/a.out
> ~piet/.cshrc: Entry
> ~piet/.cshrc: Non Interactive Shell
> ~piet/.cshrc: Not Interactive shlvl: 2
> my_printf is at 0x4000000000000880.
> &my_printf is at 0x4000000000000880.
> &my_printf[0] is at 0x4000000000000560.
> disinfo is at 0x6000000000000ba8.
> Hello World
>
> Program exited with code 014.
> (gdb) disassemble my_printf
> Dump of assembler code for function my_printf:
> 0x4000000000000560 <my_printf>: [MII] alloc r34=ar.pfs,5,4,0
> 0x4000000000000561 <my_printf+1>: mov r35=r12
> 0x4000000000000562 <my_printf+2>: mov r33=b0
> 0x4000000000000570 <my_printf+16>: [MMI] addl r14=80,r1;;
> 0x4000000000000571 <my_printf+17>: ld8 r36=[r14]
> 0x4000000000000572 <my_printf+18>: mov r32=r1
> 0x4000000000000580 <my_printf+32>: [MFB] nop.m 0x0
> 0x4000000000000581 <my_printf+33>: nop.f 0x0
> 0x4000000000000582 <my_printf+34>: br.call.sptk.many
> b0=0x4000000000000400 <_init+272>;;
> 0x4000000000000590 <my_printf+48>: [MII] mov r1=r32
> 0x4000000000000591 <my_printf+49>: mov.i ar.pfs=r34
> 0x4000000000000592 <my_printf+50>: mov b0=r33
> 0x40000000000005a0 <my_printf+64>: [MFB] mov r12=r35
> 0x40000000000005a1 <my_printf+65>: nop.f 0x0
> 0x40000000000005a2 <my_printf+66>: br.ret.sptk.many b0;;
> End of assembler dump.
> (gdb)
> ------------------------------------------------------------------
>
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