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ne0h
Joined: 21 Feb 2008
Posts: 386
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 Posted: Sun Nov 09, 2008 1:03 am Post subject: Returning data from a exported function... |
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Hi,
I'm trying to return some data from a function exported from a kernel prx and imported to a user pbp, but it crash every time!
What's the problem?
This is the exported function:
| Code: | char* GetBarraInf(void)
{
char* data="fdsfdsfds";
return data;
} |
And here I try to use it...
| Code: | | printf("%s",GetBarraInf()); |
It doesn't work, no one character is printed to screen!
Crash every time!
What I'm trying to do is export a variable ( unsigned char ) that contains a image data ( builted with bin2o )! |
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Pirata Nervo
Joined: 09 Oct 2007
Posts: 409
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| Posted: Sun Nov 09, 2008 1:15 am Post subject: |
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make sure you allocate pointers.
Also I always need pspSdkSetK1 when exporting functions otherwise it does not work for me
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 1:30 am Post subject: |
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mmm, is always needed to set K1 to 0? Is not only for "special" operations, or to remove some security protections?
Thanks! |
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 1:38 am Post subject: |
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Doesn't work whit this! ?_?
| Code: | char* GetBarraInf(void)
{
return "asd";
} |
EDIT:
Get this exception:
| Quote: | Exception - Address load/inst fetch
EPC - 0889A07C
Location - ra.text + 0009607C
Cause - 10000010
Status - 20008613
BadVAddr - 88217A40
zr:00000000 at:2008FF00 v0:88217A41 v1:0889CB38
a0:88217A40 a1:0BBBFE44 a2:00000073 a3:0BBBFE40
t0:00000068 t1:0000002B t2:00000020 t3:88065244
t4:0BBBFE58 t5:00003E0C t6:0880A5FC t7:20008600
s0:00000000 s1:FFFFFFFF s2:0BBBF63C s3:0BBBF600
s4:08930000 s5:08930000 s6:088AB9E6 s7:08930000
t8:00000000 t9:00000000 k0:0BBBFF00 k1:00000000
gp:08939230 sp:0BBBF5D0 fp:88217A40 ra:0889D7C4 |
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Badboy_
Joined: 09 Aug 2008
Posts: 4
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| Posted: Sun Nov 09, 2008 2:08 am Post subject: |
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| Code: | char* GetBarraInf(void)
{
char* data= (char*) malloc(20);
strcpy(data, "Hello, world!");
return data;
} |
does this work? |
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hlide
Joined: 10 Sep 2006
Posts: 750
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| Posted: Sun Nov 09, 2008 2:19 am Post subject: |
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*sigh*, noobish question again...
do you think making a local string in a function is making this string to be... local to this function, don't you ?
didn't it ever occur to you that adding "static" before the local string would turn it into a permanent static string you can return from your function ?
how many times do you think you need to master such a trivial error ?
well, don't answer.
EDIT:
a0:88217A40 <-- hernel address doesn't work with user code. Hint : #define USER_ADDR(x) ({ (typeof(x))(((int)(x))&~0x80000000); }) ==> return USER_ADDR("blahblah");
Last edited by hlide on Sun Nov 09, 2008 2:31 am; edited 2 times in total |
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 2:26 am Post subject: |
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Doesn't work!
Got the same exception:
| Code: |
Exception - Address load/inst fetch
EPC - 0889A07C
Location - ra.text + 0009607C
Cause - 10000010
Status - 20008613
BadVAddr - 8002013A
zr:00000000 at:00000000 v0:8002013B v1:0889CB38
a0:8002013A a1:0BBBFE44 a2:00000073 a3:0BBBFE40
t0:00000068 t1:0000002B t2:00000020 t3:88065244
t4:A8028454 t5:00003E0C t6:000000FC t7:880161C8
s0:00000000 s1:FFFFFFFF s2:0BBBF63C s3:0BBBF600
s4:08930000 s5:08930000 s6:088ABA06 s7:08930000
t8:00000000 t9:00000000 k0:0BBBFF00 k1:00000000
gp:08939250 sp:0BBBF5D0 fp:8002013A ra:0889D7C4 |
EDIT:
hlide, thanks, I'll try! |
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hlide
Joined: 10 Sep 2006
Posts: 750
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| Posted: Sun Nov 09, 2008 2:29 am Post subject: |
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| just look at registers, some registers have kernel addresses when you are running a user code... |
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hlide
Joined: 10 Sep 2006
Posts: 750
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| Posted: Sun Nov 09, 2008 2:31 am Post subject: |
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| replace 0x40000000 into 0x80000000 of course... |
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 2:43 am Post subject: |
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Tryied with this:
| Code: | static char data[20];
char* GetBarraInf(void)
{
k1 = pspSdkSetK1(0);
strcpy(data, "Hello world!");
pspSdkSetK1(k1);
return data;
} |
And it doesn't work, crash!
I've also tryied to make it a user prx but it crash!
Get the same exception:
| Code: | Exception - Address load/inst fetch
EPC - 0889A07C
Location - ra.text + 0009607C
Cause - 10000010
Status - 20008613
BadVAddr - 8002013A
zr:00000000 at:00000000 v0:8002013B v1:0889CB38
a0:8002013A a1:0BBBFE44 a2:00000073 a3:0BBBFE40
t0:00000068 t1:0000002B t2:00000020 t3:88065244
t4:A8028454 t5:00003E0C t6:000000FC t7:880161C8
s0:00000000 s1:FFFFFFFF s2:0BBBF63C s3:0BBBF600
s4:08930000 s5:08930000 s6:088ABA06 s7:08930000
t8:00000000 t9:00000000 k0:0BBBFF00 k1:00000000
gp:08939250 sp:0BBBF5D0 fp:8002013A ra:0889D7C4 |
| Quote: | | just look at registers, some registers have kernel addresses when you are running a user code... |
Sorry, doesn't know what mean the content of registers!
Never studied it! ( Have you a tuto about the content of this? )
So kernel address are 0x80000000 like, and user 0x40000000 like this, right?
| Quote: | | replace 0x40000000 into 0x80000000 of course... |
Sorry, but I've to change the a0 reg value?
EDIT:
nop, maybe I've understand! |
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hlide
Joined: 10 Sep 2006
Posts: 750
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| Posted: Sun Nov 09, 2008 2:58 am Post subject: |
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| Code: |
char const * GetBarraInf(void)
{
return (char const *)(((int)"blahblah")&~0x80000000));
}
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 3:03 am Post subject: |
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No, I haven't undestrand!
I've writed this:
| Code: |
#define USER_ADDR(x) ({ (typeof(x))(((int)(x))&~0x80000000); })
char* GetBarraInf(void);
intraFontPrintf(ltn8, 20, 20, "%s", USER_ADDR(GetBarraInf()));
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But it crash! Get Bus data error...
| Code: |
Exception - Bus error (data)
EPC - 0889A084
Location - ra.text + 00096084
Cause - 1000001C
Status - 20008613
BadVAddr - 01044400
zr:00000000 at:00000000 v0:0002013B v1:0889CB40
a0:0002013A a1:0BBBFE44 a2:00000073 a3:0BBBFE40
t0:00000068 t1:0000002B t2:00000020 t3:88065244
t4:A8028454 t5:00003E0C t6:000000FC t7:880161C8
s0:00000000 s1:FFFFFFFF s2:0BBBF63C s3:0BBBF600
s4:08930000 s5:08930000 s6:088ABA16 s7:08C80000
t8:00000000 t9:00000000 k0:0BBBFF00 k1:00000000
gp:08939260 sp:0BBBF5D0 fp:0002013A ra:0889D7CC
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Now I haven't a kernel address, right?
Anyway I've another problem... |
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 3:10 am Post subject: |
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oh my god! I got another kernel address! It crash...
| Code: |
Exception - Address load/inst fetch
EPC - 0889A068
Location - ra.text + 00096068
Cause - 10000010
Status - 20008613
BadVAddr - 8002013A
zr:00000000 at:00000000 v0:8002013B v1:0889CB24
a0:8002013A a1:0BBBFE44 a2:00000073 a3:0BBBFE40
t0:00000068 t1:0000002B t2:00000020 t3:88065244
t4:A8028454 t5:00003E0C t6:000000FC t7:880161C8
s0:00000000 s1:FFFFFFFF s2:0BBBF63C s3:0BBBF600
s4:08930000 s5:08930000 s6:088AB9E6 s7:08930000
t8:00000000 t9:00000000 k0:0BBBFF00 k1:00000000
gp:08939230 sp:0BBBF5D0 fp:8002013A ra:0889D7B0
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I'm sorry...
This is the code now:
| Code: |
static char data[20];
char const * GetBarraInf(void)
{
strcpy(data, "Hello world!");
return (char const *)(((int)data)&~0x80000000);
}
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hlide
Joined: 10 Sep 2006
Posts: 750
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| Posted: Sun Nov 09, 2008 3:41 am Post subject: |
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| Look at BadVAddr values they are abnormal... |
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 5:33 am Post subject: |
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hlide, a question:
EPC, Cause, Status and BadVAddr what means?
To work I've to change the variable addres?
But if I change the address the pointed memory is the same?
Or the kernel mode has a different mode to point a specified memory than the user mode? |
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 5:51 am Post subject: |
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Wow... Finally resolved!
| Code: | static char* data = NULL;
char const * GetBarraInf(void)
{
data = (char*)malloc(20);
strcpy(data, "Hello World!");
return (char const *)(((int)data)&~0x80000000);
}
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And before I've commented the loadmodule function, sorry! :(
But the 8002013A of
BadVAddr is == SCE_KERNEL_ERROR_LIBRARY_NOT_YET_LINKED ? |
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hlide
Joined: 10 Sep 2006
Posts: 750
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| Posted: Sun Nov 09, 2008 7:25 am Post subject: |
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no wonder.
you don't need the malloc stuff. Just be sure the pointer is a user address. |
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a_noob
Joined: 17 Sep 2006
Posts: 97
Location: _start: jr 0xDEADBEEF
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| Posted: Sun Nov 09, 2008 9:30 am Post subject: |
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heh, im too late (please ignore)
_________________
| Code: | .øOº'ºOø.
'ºOo.oOº' |
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 8:23 pm Post subject: |
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| EPC, Cause and Status what means? |
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 9:38 pm Post subject: |
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hilde, if I doesn't use malloc it crash!
But the address is a user one...
Maybe I've do something wrong...
| Code: |
static char* data = "hellooo!!";
char* GetBarraInf(void)
{
return (char*)(((int)data)&~0x80000000); // USER_ADDR(data);
}
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And in the main programm:
| Code: |
char* GetBarraInf(void);
Init(); // pspDebugScreenInit
printf("%s", GetBarraInf()); // pspDebugScreenPrintf
sleep(2000000); // sceKernelDelayThread
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The exception:
| Code: |
Exception - Bus error (data)
EPC - 0889A064
Location - ra.text + 00096064
Cause - 1000001C
Status - 20008613
BadVAddr - 01044410
zr:00000000 at:2008FF00 v0:0824E205 v1:0889CB20
a0:0824E204 a1:0BBBFE48 a2:00000073 a3:0BBBFE44
t0:00000068 t1:0000002B t2:00000020 t3:880E57F0
t4:0BBBFE60 t5:00001E04 t6:0880A4AC t7:20008600
s0:00000000 s1:FFFFFFFF s2:0BBBEF4C s3:0BBBEF10
s4:DEADBEEF s5:DEADBEEF s6:088AB9E6 s7:DEADBEEF
t8:880E5818 t9:00000028 k0:0BBBFF00 k1:00000000
gp:08939230 sp:0BBBEEE0 fp:0824E204 ra:0889D7AC
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The problem is not the address I think!
But 0x0824E204 is a strange address, right? |
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 9:44 pm Post subject: |
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Work only with this:
| Code: |
static char* data;
char* GetBarraInf(void)
{
data = (char*)malloc(20);
strcpy(data, "Hello World!!!");
return (char*)(((int)data)&~0x80000000); // USER_ADDR(data);
}
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But I can't do that, I've to return a unsiged char array...
( unsigned char data[]; <-- builted with bin2o ) |
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ne0h
Joined: 21 Feb 2008
Posts: 386
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| Posted: Sun Nov 09, 2008 11:30 pm Post subject: |
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Resolved with this... but I have to use malloc! Without that it crash!
But I haven't found the malloc function in the kernel libc, where I can find it?
I'll built the prx with the kernel libs and libc to reduce its size! |
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Pirata Nervo
Joined: 09 Oct 2007
Posts: 409
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| Posted: Mon Nov 10, 2008 1:54 am Post subject: |
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search these forums for a malloc function made by HellCat I think using the sce memory functions.
He made it exactly because kernel libc does not have it
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