Re: Kernel panic after insmod
> What exactly was the crash? And where did you find this kernel module > source from? Greg, A little digging around using Google threw this up : http://superuser.com/questions/1092083/how-to-disable-kill-command-on-linux If you scroll down you will see the exact same code :) And completely off-topic what are the options for some of us who very much wish to attend the Linux conference North America ( http://events.linuxfoundation.org/events/linuxcon-north-america ) but simply cannot afford the standard registration fee of US$950 ? And I notice Microsoft is a Diamond sponsor ? Interesting ! Aruna ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Kernel panic after insmod
On Sun, Jun 26, 2016 at 09:35:55AM +, Manavendra Nath Manav wrote:
> Can someone explain the following kernel module code. I'm not familiar with
> x86
> assembly so have problem understanding this part. Also it seems this code is
> able to modify the kernel stack.
>
> /**start/
>
> #include
>
> MODULE_LICENSE("GPL");
>
> int __init init(void) __attribute__((noreturn))
> {
> unsigned long long cr0 = read_cr0();
> write_cr0(cr0 & ~(1 << 4)); /* Clear Extension Type (ET) bit */
> *(unsigned char *)sys_kill = 0xc3; /* opcode for "ret" */
> write_cr0(cr0);
>
> /* Optional code ahead to hide traces of this module. */
> __this_module.refcnt = 1;
> __this_module.state = MODULE_STATE_LIVE;
>
> asm
> (
> "mov %0, %%rsp\n\t"
> "mov %1, %%rdi\n\t" /* name = __this_module.name */
> "xor %%rsi, %%rsi\n\t" /* flags = 0 */
> "jmp sys_delete_module\n\t" /* call delete_module(name, flags) */
> :: "r"(current->stack + THREAD_SIZE - sizeof(struct pt_regs) - 8), "r"(__
> this_module.name) :
> );
> }
>
> void __exit exit(void)
> {
> return;
> }
>
> /***end*/
What exactly was the crash? And where did you find this kernel module
source from?
greg k-h
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Kernel panic after insmod
Can someone explain the following kernel module code. I'm not familiar with
x86 assembly so have problem understanding this part. Also it seems this
code is able to modify the kernel stack.
/**start/
#include
MODULE_LICENSE("GPL");
int __init init(void) __attribute__((noreturn))
{
unsigned long long cr0 = read_cr0();
write_cr0(cr0 & ~(1 << 4)); /* Clear Extension Type (ET) bit */
*(unsigned char *)sys_kill = 0xc3; /* opcode for "ret" */
write_cr0(cr0);
/* Optional code ahead to hide traces of this module. */
__this_module.refcnt = 1;
__this_module.state = MODULE_STATE_LIVE;
asm
(
"mov %0, %%rsp\n\t"
"mov %1, %%rdi\n\t" /* name = __this_module.name */
"xor %%rsi, %%rsi\n\t" /* flags = 0 */
"jmp sys_delete_module\n\t" /* call delete_module(name, flags) */
:: "r"(current->stack + THREAD_SIZE - sizeof(struct pt_regs) - 8), "r"(__
this_module.name) :
);
}
void __exit exit(void)
{
return;
}
/***end*/
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spidev on davinci
Hello, I am trying to use spidev to send messages via spi on OMAP-L137 EVM board. I have an spidev entry in /dev, but when I try to send data, I have the following message: spidev spi1.0: SPI transfer failed: -22 spi_master spi1: failed to transfer one message from queue Debugging using printk, I found out that a probe function is called, and after this transfer_one_message is called. In transfer_one_message master->transfer_one() function is called and returned with the error. But I can't find the implementation of transfer_one function for davinci_spi. So, I have two questions: What implementation is used by default when transfer_one implementation isn't provided? Should I write my own implementation of transfer_one function& -- Regards, Denis Obrezkov ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
