diff mbox series

[2/2] x86: replace `int 0x20` with `syscall`

Message ID 20220424070207.123597-2-darcy.sh@antgroup.com (mailing list archive)
State New, archived
Headers show
Series [1/2] x86: replace `push` `pop` with callee-clobbered list | expand

Commit Message

SU Hang April 24, 2022, 7:02 a.m. UTC 
Signed-off-by: SU Hang <darcy.sh@antgroup.com>
---
 lib/x86/usermode.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/lib/x86/usermode.c b/lib/x86/usermode.c
index 477cb9f..e4cb899 100644
--- a/lib/x86/usermode.c
+++ b/lib/x86/usermode.c
@@ -12,7 +12,6 @@ 
 #include <stdint.h>
 
 #define USERMODE_STACK_SIZE	0x2000
-#define RET_TO_KERNEL_IRQ	0x20
 
 static jmp_buf jmpbuf;
 
@@ -40,9 +39,11 @@  uint64_t run_in_user(usermode_func func, unsigned int fault_vector,
 	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);
+	wrmsr(MSR_EFER, rdmsr(MSR_EFER) | EFER_SCE);
+	wrmsr(MSR_STAR, ((u64)(USER_CS32 << 16) | KERNEL_CS) << 32);
+	wrmsr(MSR_LSTAR, (u64)&ret_to_kernel);
 
 	if (setjmp(jmpbuf) != 0) {
 		*raised_vector = 1;
@@ -73,7 +74,7 @@  uint64_t run_in_user(usermode_func func, unsigned int fault_vector,
 			"mov %[arg4], %%rcx\n\t"
 			"call *%[func]\n\t"
 			/* Return to kernel via system call */
-			"int %[kernel_entry_vector]\n\t"
+			"syscall\n\t"
 			/* Kernel Mode */
 			"ret_to_kernel:\n\t"
 			"mov %[rsp0], %%rsp\n\t"
@@ -89,8 +90,7 @@  uint64_t run_in_user(usermode_func func, unsigned int fault_vector,
 			[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)
+					sizeof(user_stack))
 			:
 			"rsi", "rdi", "rbx", "rcx", "rdx", "r8", "r9", "r10", "r11");