How to call the Android/Linux system
This article mainly introduces the relevant knowledge of how to call the Android/Linux system, the content is detailed and easy to understand, the operation is simple and fast, and has a certain reference value. I believe you will gain something after reading this article on how to call the Android/Linux system. Let's take a look at it.
When debugging Android device drivers, the application layer is always bound by various permissions. Here is one of the solutions.
One kernel layer modification
Drivers/input/fingerprint/zpx_fp_mtk_tee/zpx_fp_mtk_tee.c
# include static long zpx_method (long arg) {printk ("% s enter,arg=%ld\ n", _ _ func__, arg); read_all_reg_test (fp_global); return 0 } SYSCALL_DEFINE1 (zpx_method,long,arg) / / A formal parameter {return zpx_method (arg);}
Include/linux/syscalls.h
Asmlinkage long sys_zpx_method (long arg)
Include/uapi/asm-generic/unistd.h
_ _ SYSCALL (_ _ NR_zpx_method, sys_zpx_method)
Arch/arm/include/uapi/asm/unistd.h
# define _ _ NR_zpx_method (_ _ NR_SYSCALL_BASE+391)
Arch/arm/kernel/calls.S
CALL (sys_zpx_method) .rept syscalls_padding / / comments such as the empty function / * CALL (sys_ni_syscall) * / / * null func*/
Arch/arm/include/asm/unistd.h
# define _ NR_syscalls / / last call + 1
Application layer invocation
# include # define _ SYSCALL_zpx_ 391int main (int argc,char * * argv) {syscall (_ SYSCALL_zpx_,13); return 0;}
Three results
No permission is required
K39_bsp:/data/local/tmp $ls-ltotal 80-rwxrwxrwx 1 shell shell 78968 2020-07-20 09:28 driver_testk39_bsp:/data/local/tmp $. / driver_testk39_bsp:/data/local/tmp $
Kernel log
[100.325202] (2) [2506:driver_test] zpx_method enter Arg=13 [100.325234] (2) [2506:driver_test] [zpx] zpx_spi_clk_enable enter [100.325249] (2) [2506:driver_test] [zpx] zpx_spi_clk_enable finsish [100.325469] (2) [2506:driver_test] [zpx] [0] = FF [100.325483] (2) [2506:driver_test] [zpx] [1] = 0 [100.325490] (2) [2506: Driver_test] [zpx] [2] = 0 [100.325497] (2) [2506:driver_test] [zpx] [3] = 3F [100.325503] (2) [2506:driver_test] [zpx] [4] = 0 [100.325510] (2) [2506:driver_test] [zpx] [5] = 57 this is the end of the article on "how to call the Android/Linux system" Thank you for reading! I believe you all have a certain understanding of the knowledge of "how to call the Android/Linux system". If you want to learn more, you are welcome to follow the industry information channel.
