x86: split ret_from_fork (7076aada) · Commits · e / devices / android_kernel_oneplus_sm7250

arch/x86/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -97,6 +97,7 @@ config X86
		select KTIME_SCALAR if X86_32
		select GENERIC_STRNCPY_FROM_USER
		select GENERIC_STRNLEN_USER
		select GENERIC_KERNEL_THREAD

		config INSTRUCTION_DECODER
		def_bool (KPROBES \|\| PERF_EVENTS \|\| UPROBES)

+0 −5

Original line number	Diff line number	Diff line
		@@ -589,11 +589,6 @@ typedef struct {
		} mm_segment_t;


		/*
		* create a kernel thread without removing it from tasklists
		*/
		extern int kernel_thread(int (fn)(void ), void *arg, unsigned long flags);

		/* Free all resources held by a thread. */
		extern void release_thread(struct task_struct *);

+10 −5

Original line number	Diff line number	Diff line
		@@ -994,15 +994,20 @@ END(spurious_interrupt_bug)
		*/
		.popsection

		ENTRY(kernel_thread_helper)
		pushl $0 # fake return address for unwinder
		ENTRY(ret_from_kernel_thread)
		CFI_STARTPROC
		movl %edi,%eax
		call *%esi
		pushl_cfi %eax
		call schedule_tail
		GET_THREAD_INFO(%ebp)
		popl_cfi %eax
		pushl_cfi $0x0202 # Reset kernel eflags
		popfl_cfi
		movl PT_EBP(%esp),%eax
		call *PT_EBX(%esp)
		call do_exit
		ud2 # padding for call trace
		CFI_ENDPROC
		ENDPROC(kernel_thread_helper)
		ENDPROC(ret_from_kernel_thread)

		#ifdef CONFIG_XEN
		/* Xen doesn't set %esp to be precisely what the normal sysenter

+11 −16

Original line number	Diff line number	Diff line
		@@ -450,7 +450,7 @@ ENTRY(ret_from_fork)
		RESTORE_REST

		testl $3, CS-ARGOFFSET(%rsp) # from kernel_thread?
		jz retint_restore_args
		jz 1f

		testl $_TIF_IA32, TI_flags(%rcx) # 32-bit compat task needs IRET
		jnz int_ret_from_sys_call
		@@ -458,6 +458,16 @@ ENTRY(ret_from_fork)
		RESTORE_TOP_OF_STACK %rdi, -ARGOFFSET
		jmp ret_from_sys_call # go to the SYSRET fastpath

		1:
		subq $REST_SKIP, %rsp # move the stack pointer back
		CFI_ADJUST_CFA_OFFSET REST_SKIP
		movq %rbp, %rdi
		call *%rbx
		# exit
		mov %eax, %edi
		call do_exit
		ud2 # padding for call trace

		CFI_ENDPROC
		END(ret_from_fork)

		@@ -1206,21 +1216,6 @@ bad_gs:
		jmp 2b
		.previous

		ENTRY(kernel_thread_helper)
		pushq $0 # fake return address
		CFI_STARTPROC
		/*
		* Here we are in the child and the registers are set as they were
		* at kernel_thread() invocation in the parent.
		*/
		call *%rsi
		# exit
		mov %eax, %edi
		call do_exit
		ud2 # padding for call trace
		CFI_ENDPROC
		END(kernel_thread_helper)

		/*
		* execve(). This function needs to use IRET, not SYSRET, to set up all state properly.
		*

+0 −38

Original line number	Diff line number	Diff line
		@@ -298,44 +298,6 @@ sys_clone(unsigned long clone_flags, unsigned long newsp,
		return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
		}

		/*
		* This gets run with %si containing the
		* function to call, and %di containing
		* the "args".
		*/
		extern void kernel_thread_helper(void);

		/*
		* Create a kernel thread
		*/
		int kernel_thread(int (fn)(void ), void *arg, unsigned long flags)
		{
		struct pt_regs regs;

		memset(&regs, 0, sizeof(regs));

		regs.si = (unsigned long) fn;
		regs.di = (unsigned long) arg;

		#ifdef CONFIG_X86_32
		regs.ds = __USER_DS;
		regs.es = __USER_DS;
		regs.fs = __KERNEL_PERCPU;
		regs.gs = __KERNEL_STACK_CANARY;
		#else
		regs.ss = __KERNEL_DS;
		#endif

		regs.orig_ax = -1;
		regs.ip = (unsigned long) kernel_thread_helper;
		regs.cs = __KERNEL_CS \| get_kernel_rpl();
		regs.flags = X86_EFLAGS_IF \| X86_EFLAGS_BIT1;

		/* Ok, create the new process.. */
		return do_fork(flags \| CLONE_VM \| CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
		}
		EXPORT_SYMBOL(kernel_thread);

		/*
		* sys_execve() executes a new program.
		*/