Improve syscall implementation #284
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Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
The terminate_user_task() is used upon exception when in usermode. Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
Main change is a split of the syscall implementation with proper assembly routines: syscall_handler_entry() and simplified syscall_exit() and a simplified C-level syscall handler function. The syscall_exit() is implemented and handled fully in asm. The syscall() usermode function implements typical syscall ABI, passing syscall number via AX register and the rest of parameters via SI, DX, DI, R8 and R9. The assembly entry point rearranges the registers to fix the C-level handler function API. Only 5 arguments to the syscall can be provided. Usermode upon calling syscall() takes are of callee saved registers by saving/restoring them via usermode stack (only reminder of unused registers is preserved as the rest is considered implicitely clobbered). Additionally SYSCALL_PRINTF has been improved to support variadic number of arguments (it passes the va_list args to the kernel mode). Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
In 64bit mode push 64bit 0 value on the stack as the aligning error code and overwrite upper 32 bits of it with vector value. In 32bit mode push 32bit 0 value on the stack as the aligning error code and push vector value additionally. Signed-off-by: Pawel Wieczorkiewicz <[email protected]>
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Note: This PR is based on #282. Please review and merge #282 first or focus only on the new bits.