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Support user manage stack

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Go/Java/JIT code manage their own stack
So we need to help them to handle exception
This commit is contained in:
zongmin.gu 2020-05-12 21:45:44 +08:00 committed by Tate, Hongliang Tian
parent aed572064b
commit eca27408be
3 changed files with 9 additions and 40 deletions
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2
src/libos/include/task.h
View File

@ -38,8 +38,6 @@ void do_exit_task(void);
#else /* __ASSEMBLY__ */
/* See /<path-to-linux-sgx>/common/inc/internal/thread_data.h */
#define TD_STACK_BASE (8 * 2)
#define TD_STACK_LIMIT (8 * 3)
#define TD_STACKGUARD_OFFSET (8 * 5)
/* Override the field for stack guard */
#define TD_TASK_OFFSET TD_STACKGUARD_OFFSET

32
src/libos/src/process/task/task.c
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@ -1,3 +1,4 @@
#include <assert.h>
#include "task.h"
/* See /<path-to-linux-sgx>/common/inc/internal/thread_data.h */
@ -22,6 +23,8 @@ extern void __set_stack_guard(uint64_t new_val);
int sgx_enable_user_stack(size_t stack_base, size_t stack_limit);
void sgx_disable_user_stack(void);
#define OCCLUM_PAGE_SIZE 4096
static uint64_t get_syscall_stack(struct Task* this_task) {
#define LARGE_ENOUGH_GAP (8192)
char libos_stack_var = 0;
@ -37,28 +40,6 @@ static uint64_t get_syscall_stack(struct Task* this_task) {
#define RESET_CURRENT_TASK() \
__set_stack_guard(stack_guard);
void switch_td_to_kernel(const struct Task* task) {
thread_data_t* td = get_thread_data();
// TODO: do do not support stack expansion, need a new design on SGX2 platform.
// Set the stack_commit_addr to 0, as the result no stack expansion happens at any situations
__atomic_store_n(&td->stack_commit_addr, 0, __ATOMIC_RELAXED);
td->stack_base_addr = task->kernel_stack_base;
td->stack_limit_addr = task->kernel_stack_limit;
td->stack_commit_addr = task->kernel_stack_limit;
}
void switch_td_to_user(const struct Task* task) {
thread_data_t* td = get_thread_data();
// TODO: do do not support stack expansion, need a new design on SGX2 platform.
// Set the stack_commit_addr to 0, as the result no stack expansion happens at any situations
__atomic_store_n(&td->stack_commit_addr, 0, __ATOMIC_RELAXED);
td->stack_base_addr = task->user_stack_base;
td->stack_limit_addr = task->user_stack_limit;
td->stack_commit_addr = task->user_stack_limit;
}
int do_exec_task(struct Task* task) {
jmp_buf libos_state = {0};
thread_data_t* td = get_thread_data();
@ -67,7 +48,10 @@ int do_exec_task(struct Task* task) {
task->kernel_stack_base = td->stack_base_addr;
task->kernel_stack_limit = td->stack_limit_addr;
switch_td_to_user(task);
//Reserve two pages stack for exception handler
//The SGX SDK exception handler depends on the two pages as stack to handle exceptions in user's code
//TODO:Add a check in the sysreturn logic to confirm the stack is not corrupted
assert(task->kernel_stack_limit+OCCLUM_PAGE_SIZE*2 <= task->kernel_rsp);
SET_CURRENT_TASK(task);
@ -84,7 +68,5 @@ int do_exec_task(struct Task* task) {
void do_exit_task(void) {
struct Task* task = __get_current_task();
jmp_buf* jb = task->saved_state;
switch_td_to_kernel(task);
longjmp(*jb, 1);
}

15
src/libos/src/syscall/syscall_entry_x86-64.S
View File

@ -65,13 +65,8 @@ __occlum_syscall_linux_abi:
#else // SGX_MODE_HW
movq TASK_KERNEL_FS(%r12), %r11
wrfsbase %r11
#endif
// Switch to kernel stack base and limit
movq TASK_KERNEL_STACK_BASE(%r12), %r11
movq %r11, %gs:TD_STACK_BASE
movq TASK_KERNEL_STACK_LIMIT(%r12), %r11
movq %r11, %gs:TD_STACK_LIMIT
#endif
call occlum_syscall
// This should never happen!
@ -116,12 +111,6 @@ __occlum_sysret:
movq TASK_USER_FS(%r12), %r11
wrfsbase %r11
#endif
// Switch to user stack base and limit
movq TASK_USER_STACK_BASE(%r12), %r11
movq %r11, %gs:TD_STACK_BASE
movq TASK_USER_STACK_LIMIT(%r12), %r11
movq %r11, %gs:TD_STACK_LIMIT
// Restore flags first
leaq (17*8)(%rdi), %rsp
popfq