diff options
Diffstat (limited to 'arch/x86/entry')
| -rw-r--r-- | arch/x86/entry/entry_32.S | 53 | ||||
| -rw-r--r-- | arch/x86/entry/entry_64.S | 43 | ||||
| -rw-r--r-- | arch/x86/entry/vdso/vma.c | 4 |
3 files changed, 35 insertions, 65 deletions
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 91397f58ac30..6e6af42e044a 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -720,26 +720,6 @@ SYM_CODE_END(__switch_to_asm) .popsection /* - * The unwinder expects the last frame on the stack to always be at the same - * offset from the end of the page, which allows it to validate the stack. - * Calling schedule_tail() directly would break that convention because its an - * asmlinkage function so its argument has to be pushed on the stack. This - * wrapper creates a proper "end of stack" frame header before the call. - */ -.pushsection .text, "ax" -SYM_FUNC_START(schedule_tail_wrapper) - FRAME_BEGIN - - pushl %eax - call schedule_tail - popl %eax - - FRAME_END - RET -SYM_FUNC_END(schedule_tail_wrapper) -.popsection - -/* * A newly forked process directly context switches into this address. * * eax: prev task we switched from @@ -747,29 +727,22 @@ SYM_FUNC_END(schedule_tail_wrapper) * edi: kernel thread arg */ .pushsection .text, "ax" -SYM_CODE_START(ret_from_fork) - call schedule_tail_wrapper +SYM_CODE_START(ret_from_fork_asm) + movl %esp, %edx /* regs */ - testl %ebx, %ebx - jnz 1f /* kernel threads are uncommon */ + /* return address for the stack unwinder */ + pushl $.Lsyscall_32_done -2: - /* When we fork, we trace the syscall return in the child, too. */ - movl %esp, %eax - call syscall_exit_to_user_mode - jmp .Lsyscall_32_done + FRAME_BEGIN + /* prev already in EAX */ + movl %ebx, %ecx /* fn */ + pushl %edi /* fn_arg */ + call ret_from_fork + addl $4, %esp + FRAME_END - /* kernel thread */ -1: movl %edi, %eax - CALL_NOSPEC ebx - /* - * A kernel thread is allowed to return here after successfully - * calling kernel_execve(). Exit to userspace to complete the execve() - * syscall. - */ - movl $0, PT_EAX(%esp) - jmp 2b -SYM_CODE_END(ret_from_fork) + RET +SYM_CODE_END(ret_from_fork_asm) .popsection SYM_ENTRY(__begin_SYSENTER_singlestep_region, SYM_L_GLOBAL, SYM_A_NONE) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index f31e286c2977..43606de22511 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -284,36 +284,33 @@ SYM_FUNC_END(__switch_to_asm) * r12: kernel thread arg */ .pushsection .text, "ax" - __FUNC_ALIGN -SYM_CODE_START_NOALIGN(ret_from_fork) +SYM_CODE_START(ret_from_fork_asm) + /* + * This is the start of the kernel stack; even through there's a + * register set at the top, the regset isn't necessarily coherent + * (consider kthreads) and one cannot unwind further. + * + * This ensures stack unwinds of kernel threads terminate in a known + * good state. + */ UNWIND_HINT_END_OF_STACK ANNOTATE_NOENDBR // copy_thread CALL_DEPTH_ACCOUNT - movq %rax, %rdi - call schedule_tail /* rdi: 'prev' task parameter */ - testq %rbx, %rbx /* from kernel_thread? */ - jnz 1f /* kernel threads are uncommon */ + movq %rax, %rdi /* prev */ + movq %rsp, %rsi /* regs */ + movq %rbx, %rdx /* fn */ + movq %r12, %rcx /* fn_arg */ + call ret_from_fork -2: - UNWIND_HINT_REGS - movq %rsp, %rdi - call syscall_exit_to_user_mode /* returns with IRQs disabled */ - jmp swapgs_restore_regs_and_return_to_usermode - -1: - /* kernel thread */ - UNWIND_HINT_END_OF_STACK - movq %r12, %rdi - CALL_NOSPEC rbx /* - * A kernel thread is allowed to return here after successfully - * calling kernel_execve(). Exit to userspace to complete the execve() - * syscall. + * Set the stack state to what is expected for the target function + * -- at this point the register set should be a valid user set + * and unwind should work normally. */ - movq $0, RAX(%rsp) - jmp 2b -SYM_CODE_END(ret_from_fork) + UNWIND_HINT_REGS + jmp swapgs_restore_regs_and_return_to_usermode +SYM_CODE_END(ret_from_fork_asm) .popsection .macro DEBUG_ENTRY_ASSERT_IRQS_OFF diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index 11a5c68d1218..7645730dc228 100644 --- a/arch/x86/entry/vdso/vma.c +++ b/arch/x86/entry/vdso/vma.c @@ -299,8 +299,8 @@ static unsigned long vdso_addr(unsigned long start, unsigned len) /* Round the lowest possible end address up to a PMD boundary. */ end = (start + len + PMD_SIZE - 1) & PMD_MASK; - if (end >= TASK_SIZE_MAX) - end = TASK_SIZE_MAX; + if (end >= DEFAULT_MAP_WINDOW) + end = DEFAULT_MAP_WINDOW; end -= len; if (end > start) { |