| #include "x86/msr.h" |
| #include "x86/processor.h" |
| #include "x86/apic-defs.h" |
| #include "x86/apic.h" |
| #include "x86/desc.h" |
| #include "x86/isr.h" |
| #include "alloc.h" |
| #include "setjmp.h" |
| #include "usermode.h" |
| |
| #include "libcflat.h" |
| #include <stdint.h> |
| |
| #define USERMODE_STACK_SIZE 0x2000 |
| #define RET_TO_KERNEL_IRQ 0x20 |
| |
| static jmp_buf jmpbuf; |
| |
| static void restore_exec_to_jmpbuf(void) |
| { |
| longjmp(jmpbuf, 1); |
| } |
| |
| static void restore_exec_to_jmpbuf_exception_handler(struct ex_regs *regs) |
| { |
| /* longjmp must happen after iret, so do not do it now. */ |
| regs->rip = (unsigned long)&restore_exec_to_jmpbuf; |
| regs->cs = KERNEL_CS; |
| } |
| |
| uint64_t run_in_user(usermode_func func, unsigned int fault_vector, |
| uint64_t arg1, uint64_t arg2, uint64_t arg3, |
| uint64_t arg4, bool *raised_vector) |
| { |
| extern char ret_to_kernel; |
| uint64_t rax = 0; |
| static unsigned char user_stack[USERMODE_STACK_SIZE]; |
| |
| *raised_vector = 0; |
| set_idt_entry(RET_TO_KERNEL_IRQ, &ret_to_kernel, 3); |
| handle_exception(fault_vector, |
| restore_exec_to_jmpbuf_exception_handler); |
| |
| if (setjmp(jmpbuf) != 0) { |
| *raised_vector = 1; |
| return 0; |
| } |
| |
| asm volatile ( |
| /* Backing Up Stack in rdi */ |
| "mov %%rsp, %%rdi\n\t" |
| /* Load user_ds to DS and ES */ |
| "mov %[user_ds], %%ax\n\t" |
| "mov %%ax, %%ds\n\t" |
| "mov %%ax, %%es\n\t" |
| /* IRET into user mode */ |
| "pushq %[user_ds]\n\t" |
| "pushq %[user_stack_top]\n\t" |
| "pushfq\n\t" |
| "pushq %[user_cs]\n\t" |
| "pushq $user_mode\n\t" |
| "iretq\n" |
| |
| "user_mode:\n\t" |
| /* Back up registers before invoking func */ |
| "push %%rbx\n\t" |
| "push %%rcx\n\t" |
| "push %%rdx\n\t" |
| "push %%r8\n\t" |
| "push %%r9\n\t" |
| "push %%r10\n\t" |
| "push %%r11\n\t" |
| "push %%rdi\n\t" |
| "push %%rsi\n\t" |
| /* Call user mode function */ |
| "mov %[arg1], %%rdi\n\t" |
| "mov %[arg2], %%rsi\n\t" |
| "mov %[arg3], %%rdx\n\t" |
| "mov %[arg4], %%rcx\n\t" |
| "call *%[func]\n\t" |
| /* Restore registers */ |
| "pop %%rsi\n\t" |
| "pop %%rdi\n\t" |
| "pop %%r11\n\t" |
| "pop %%r10\n\t" |
| "pop %%r9\n\t" |
| "pop %%r8\n\t" |
| "pop %%rdx\n\t" |
| "pop %%rcx\n\t" |
| "pop %%rbx\n\t" |
| /* Return to kernel via system call */ |
| "int %[kernel_entry_vector]\n\t" |
| /* Kernel Mode */ |
| "ret_to_kernel:\n\t" |
| "mov %%rdi, %%rsp\n\t" |
| : |
| "+a"(rax) |
| : |
| [arg1]"m"(arg1), |
| [arg2]"m"(arg2), |
| [arg3]"m"(arg3), |
| [arg4]"m"(arg4), |
| [func]"m"(func), |
| [user_ds]"i"(USER_DS), |
| [user_cs]"i"(USER_CS), |
| [user_stack_top]"r"(user_stack + |
| sizeof(user_stack)), |
| [kernel_entry_vector]"i"(RET_TO_KERNEL_IRQ) |
| : |
| "rsi", "rdi", "rcx", "rdx"); |
| |
| return rax; |
| } |