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[solved] sceKernelLoadModule in kernel mode

 
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Beuc



Joined: 26 Mar 2009
Posts: 33
Location: holland
PostPosted: Wed May 20, 2009 4:55 am    Post subject: [solved] sceKernelLoadModule in kernel mode Reply with quote
Hi,

I'm trying to load a module from within a kernel module.

When I use:
Code:
SceUID modid = sceKernelLoadModule("hello.prx", 0, &option);


from the kernel module, it returns 0x80020149 (SCE_KERNEL_ERROR_ILLEGAL_PERM_CALL).

I tried using USE_KERNEL_LIBS=1 to allow the kernel to use user-mode (as per I read at http://forums.ps2dev.org/viewtopic.php?p=66785), but that doesn't seem to work. pspSdkSetK1(0) doesn't help either.

How should I use sceKernelLoadModule in kernel mode?

Last edited by Beuc on Thu May 21, 2009 7:15 pm; edited 1 time in total
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Torch



Joined: 28 May 2008
Posts: 842
PostPosted: Wed May 20, 2009 11:17 pm    Post subject: Reply with quote
First of all when making a kernel module always use USE_KERNEL_LIBS=1 and USE_KERNEL_LIBC=1 or you'll end up with bloated code like 100KiB for a kernel module which would normally be 2KiB. And you're ideally not supposed to use user functions from kernel mode either. Find a way without the user functions.

Regarding your problem:
The cwd may not be set. Give the full path for hello.prx

The &options struct may not be set properly. Anyway it's not necessary for simple loading so make it NULL..

It may not work from inside module_start and some non-thread contexts. Make sure you are calling it from a thread.
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Beuc



Joined: 26 Mar 2009
Posts: 33
Location: holland
PostPosted: Thu May 21, 2009 5:15 am    Post subject: Reply with quote
Thanks Torch.

Here's the code, I'm trying to follow your advice:
Code:

#include <pspsdk.h>
#include <pspkernel.h>
#include <string.h>
#include <stdio.h>

PSP_MODULE_INFO("nanofe", 0x1007, 1, 0);
PSP_MAIN_THREAD_ATTR(PSP_THREAD_ATTR_USER);

int plugin_thread (SceSize argc, void* argp)
{
  char buf[100];

  SceUID fd = sceIoOpen ("host0:/plugin_pspain.dat",
          PSP_O_WRONLY | PSP_O_CREAT | PSP_O_TRUNC, 0777);
  if (fd < 0)
    return -1;

  SceKernelLMOption option;
  memset(&option, 0, sizeof(option));
  option.size = sizeof(option);
  option.mpidtext = 2;
  option.mpiddata = 2;
  option.position = 0;
  option.access = 1;
  char args[2048];

  u32 k1 = pspSdkSetK1(0);

  //SceUID (* sceKernelLoadModule_k)(const char *path, int flags, SceKernelLMOption *option);
  //sceKernelLoadModule_k = (void *)FindProc("sceModuleManager", "ModuleMgrForKernel", 0x977de386);

  sceKernelDelayThread(1000 * 1000);
  while(!sceKernelFindModuleByName("sceKernelLibrary")) sceKernelDelayThread(100 * 1000);
  SceUID modid = sceKernelLoadModule("ms0:/PSP/GAME/meminfo-prx-large/hello.prx", 0, NULL);

  sceIoWrite (fd, "modid=", 7);
  sprintf(buf, "%p\n", modid);
  sceIoWrite (fd, buf, 100);
  int mresult;
  sceKernelStartModule(modid, 0, args, &mresult, NULL);
  sceIoWrite (fd, "end\n", 4);

  pspSdkSetK1(k1);

  sceIoClose (fd);

  // Completely free all memory
  sceKernelSelfStopUnloadModule(1, 0, NULL);
  return 0;

}

int
module_start (SceSize argc, void* argp)
{
  u32 func = 0x80000000 | (u32)plugin_thread;
  SceUID thread = sceKernelCreateThread("plugin_thread",
               (void*)func, 0x30, 0x10000, 0, NULL);
  if (thread >= 0) {
    sceKernelStartThread (thread, argc, argp);
  }
  return 0;
}


and Makefile:
Code:

PSP_LARGE_MEMORY=1
TARGET = plugin
OBJS = module.o

CFLAGS = -O2 -G0 -Wall
CXXFLAGS = $(CFLAGS) -fno-exceptions -fno-rtti
ASFLAGS = $(CFLAGS)

LDFLAGS += -mno-crt0 -nostartfiles

BUILD_PRX=1
PSP_FW_VERSION=303
#USE_PSPSDK_LIBC=1
USE_KERNEL_LIBC=1
USE_KERNEL_LIBS=1

EXTRA_TARGETS = EBOOT.PBP
PSP_EBOOT_TITLE = plugin

PSPSDK=$(shell psp-config --pspsdk-path)

include $(PSPSDK)/lib/build.mak




Torch wrote:
First of all when making a kernel module always use USE_KERNEL_LIBS=1 and USE_KERNEL_LIBC=1 or you'll end up with bloated code like 100KiB for a kernel module which would normally be 2KiB.


Hmm, I get a 72kB .prx.

Torch wrote:
And you're ideally not supposed to use user functions from kernel mode either. Find a way without the user functions.


Well I don't have a clue about loading the module otherwise. Any lead?

Torch wrote:

Regarding your problem:
The cwd may not be set. Give the full path for hello.prx


It doesn't help, but in fact even specifying "blah" will return 0x80020149.

Quote:
The &options struct may not be set properly. Anyway it's not necessary for simple loading so make it NULL..


Neither :/

Quote:
It may not work from inside module_start and some non-thread contexts. Make sure you are calling it from a thread.


It's in a thread already.
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Beuc



Joined: 26 Mar 2009
Posts: 33
Location: holland
PostPosted: Thu May 21, 2009 7:13 am    Post subject: Reply with quote
Beuc wrote:

Code:

USE_KERNEL_LIBC=1
USE_KERNEL_LIBS=1



Hmmm, it doesn't show on the forum but did you know that a trailing space in 'USE_KERNEL_LIBC=1 ' can seriously mess you build? Just learnt about it XD

Arrrrrrrrrrrrrrrrrrrrrrrrrrgh!!!
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Torch



Joined: 28 May 2008
Posts: 842
PostPosted: Thu May 21, 2009 6:22 pm    Post subject: Reply with quote
Lot of unnecessary crap in your code. And yes the trailing spaces in the makefile lines screw things up.

Not tested, but this should be enough.

Code:
#include <pspsdk.h>
#include <pspkernel.h>
#include <string.h>
#include <stdio.h>

PSP_MODULE_INFO("nanofe", 0x1000, 1, 0); //0x1007 cannot be stopped and unloaded
PSP_MAIN_THREAD_ATTR(0); //0 for kernel thread

int plugin_thread (SceSize argc, void* argp)
{
  sceIoChdir(argp); //Might need to append trailing / here.
  char buf[100];

  SceUID fd = sceIoOpen ("host0:/plugin_pspain.dat",
          PSP_O_WRONLY | PSP_O_CREAT | PSP_O_TRUNC, 0777);
  if (fd < 0)
    return -1;

  SceUID modid = sceKernelLoadModule("ms0:/PSP/GAME/meminfo-prx-large/hello.prx", 0, NULL);

  sceIoWrite (fd, "modid=", 7);
  sprintf(buf, "%p\n", modid);
  sceIoWrite (fd, buf, 100);
  int mresult;
  sceKernelStartModule(modid, 0, NULL, &mresult, NULL); //why args for 0 length. pass NULL instead?
  sceIoWrite (fd, "end\n", 4);

  sceIoClose (fd);

  // Completely free all memory
  sceKernelSelfStopUnloadModule(1, 0, NULL);
  return 0;

}

int module_start (SceSize argc, void* argp)
{
  SceUID thread = sceKernelCreateThread("plugin_thread",
               plugin_thread, 0x30, 0x10000, 0, NULL); //this is enough
  if (thread >= 0) {
    sceKernelStartThread (thread, argc, argp);
  }
  return 0;
}
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Beuc



Joined: 26 Mar 2009
Posts: 33
Location: holland
PostPosted: Thu May 21, 2009 7:14 pm    Post subject: Reply with quote
Thanks for your answer.

Torch wrote:
Lot of unnecessary crap in your code. And yes the trailing spaces in the makefile lines screw things up.


Yes, the code was as-is, since I was aiming at getting something that worked before trying to trim it.

I wasn't clear, but actually the Makefile bug was the only thing to fix :]

Code:

sceIoChdir(argp); //Might need to append trailing / here.


I'd say we need to remove the file part, as argp is normally the path to the current executable. To make things simple I built full paths (getcwd() + "stuff.prx") from the SDL front-end.

For reference, here's the code:
Code:

#include <pspsdk.h>
#include <pspkernel.h>
#include <string.h>

PSP_MODULE_INFO("klauncher", 0x1000, 1, 0);
PSP_MAIN_THREAD_ATTR(0); // kernel thread

int klauncher_thread (SceSize args, char* argp)
{
  SceUID modid = sceKernelLoadModule(argp, 0, NULL);
  if (modid > 0)
    {
      int ignored_mresult;
      sceKernelStartModule(modid, args, argp, &ignored_mresult, NULL);
    }
 
  // Completely free all memory
  sceKernelSelfStopUnloadModule(1, 0, NULL);

  return 0;
}

int
module_start (SceSize args, char* argp)
{
  /* We need to run sceKernelLoadModule from a thread */
  SceUID thread = sceKernelCreateThread("klauncher_thread",
               (void*)klauncher_thread, 0x30, 0x10000, 0, NULL);
  if (thread >= 0) {
    /* Drop first argument (path to current module) */
    int i = 0;
    while(argp[i] != '\0') i++;
    i++;
    sceKernelStartThread (thread, args-i, argp+i);
  }
  return 0;
}


and Makefile:
Code:

TARGET = klauncher
OBJS = klauncher.o

CFLAGS = -O2 -G0 -Wall
CXXFLAGS = $(CFLAGS) -fno-exceptions -fno-rtti

LDFLAGS += -mno-crt0 -nostartfiles

BUILD_PRX=1
#PSP_FW_VERSION=303

EXTRA_TARGETS = EBOOT.PBP
PSP_EBOOT_TITLE = klauncher

PSP_LARGE_MEMORY=1
USE_KERNEL_LIBC=1
USE_KERNEL_LIBS=1

PSPSDK=$(shell psp-config --pspsdk-path)
include $(PSPSDK)/lib/build.mak
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