From 22e2430d60dbdfcdd732a086e9ef2dbd74c266d1 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Wed, 10 Oct 2012 21:35:42 -0400 Subject: [PATCH] x86, um: convert to saner kernel_execve() semantics Signed-off-by: Al Viro --- arch/um/include/asm/processor-generic.h | 2 -- arch/um/include/shared/os.h | 1 - arch/um/kernel/exec.c | 5 ---- arch/um/kernel/process.c | 10 +++----- arch/um/os-Linux/process.c | 13 ----------- arch/x86/Kconfig | 1 + arch/x86/include/asm/unistd.h | 1 - arch/x86/kernel/entry_32.S | 31 ++++++++++--------------- arch/x86/kernel/entry_64.S | 24 ++++--------------- arch/x86/um/Kconfig | 1 + 10 files changed, 21 insertions(+), 68 deletions(-) diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h index 5d9ab0c4f488..62435a00e70e 100644 --- a/arch/um/include/asm/processor-generic.h +++ b/arch/um/include/asm/processor-generic.h @@ -26,7 +26,6 @@ struct thread_struct { jmp_buf *fault_catcher; struct task_struct *prev_sched; unsigned long temp_stack; - jmp_buf *exec_buf; struct arch_thread arch; jmp_buf switch_buf; int mm_count; @@ -54,7 +53,6 @@ struct thread_struct { .fault_addr = NULL, \ .prev_sched = NULL, \ .temp_stack = 0, \ - .exec_buf = NULL, \ .arch = INIT_ARCH_THREAD, \ .request = { 0 } \ } diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h index 89b686c1a3ea..25dbd372d322 100644 --- a/arch/um/include/shared/os.h +++ b/arch/um/include/shared/os.h @@ -191,7 +191,6 @@ extern int os_getpid(void); extern int os_getpgrp(void); extern void init_new_thread_signals(void); -extern int run_kernel_thread(int (*fn)(void *), void *arg, jmp_buf **jmp_ptr); extern int os_map_memory(void *virt, int fd, unsigned long long off, unsigned long len, int r, int w, int x); diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c index e427301f55d6..565ca396d83e 100644 --- a/arch/um/kernel/exec.c +++ b/arch/um/kernel/exec.c @@ -47,8 +47,3 @@ void start_thread(struct pt_regs *regs, unsigned long eip, unsigned long esp) #endif } EXPORT_SYMBOL(start_thread); - -void __noreturn ret_from_kernel_execve(struct pt_regs *unused) -{ - UML_LONGJMP(current->thread.exec_buf, 1); -} diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c index a1b50add48a2..94b0d8b9810b 100644 --- a/arch/um/kernel/process.c +++ b/arch/um/kernel/process.c @@ -135,14 +135,10 @@ void new_thread_handler(void) arg = current->thread.request.u.thread.arg; /* - * The return value is 1 if the kernel thread execs a process, - * 0 if it just exits + * callback returns only if the kernel thread execs a process */ - n = run_kernel_thread(fn, arg, ¤t->thread.exec_buf); - if (n == 1) - userspace(¤t->thread.regs.regs); - else - do_exit(0); + n = fn(arg); + userspace(¤t->thread.regs.regs); } /* Called magically, see new_thread_handler above */ diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c index 307f173e7f82..a04ec167a9c3 100644 --- a/arch/um/os-Linux/process.c +++ b/arch/um/os-Linux/process.c @@ -244,16 +244,3 @@ void init_new_thread_signals(void) signal(SIGWINCH, SIG_IGN); signal(SIGTERM, SIG_DFL); } - -int run_kernel_thread(int (*fn)(void *), void *arg, jmp_buf **jmp_ptr) -{ - jmp_buf buf; - int n; - - *jmp_ptr = &buf; - n = UML_SETJMP(&buf); - if (n != 0) - return n; - (*fn)(arg); - return 0; -} diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index d93eb9d1bb97..45edcba41e39 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -98,6 +98,7 @@ config X86 select GENERIC_STRNCPY_FROM_USER select GENERIC_STRNLEN_USER select GENERIC_KERNEL_THREAD + select GENERIC_KERNEL_EXECVE config INSTRUCTION_DECODER def_bool (KPROBES || PERF_EVENTS || UPROBES) diff --git a/arch/x86/include/asm/unistd.h b/arch/x86/include/asm/unistd.h index 55d155560fdf..16f3fc6ebf2e 100644 --- a/arch/x86/include/asm/unistd.h +++ b/arch/x86/include/asm/unistd.h @@ -51,7 +51,6 @@ # define __ARCH_WANT_SYS_UTIME # define __ARCH_WANT_SYS_WAITPID # define __ARCH_WANT_SYS_EXECVE -# define __ARCH_WANT_KERNEL_EXECVE /* * "Conditional" syscalls diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index fe4cc305d8da..91d295908c30 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -298,12 +298,20 @@ ENTRY(ret_from_fork) CFI_ENDPROC END(ret_from_fork) -ENTRY(ret_from_kernel_execve) - movl %eax, %esp - movl $0,PT_EAX(%esp) +ENTRY(ret_from_kernel_thread) + CFI_STARTPROC + 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) + movl $0,PT_EAX(%esp) jmp syscall_exit -END(ret_from_kernel_execve) + CFI_ENDPROC +ENDPROC(ret_from_kernel_thread) /* * Interrupt exit functions should be protected against kprobes @@ -994,21 +1002,6 @@ END(spurious_interrupt_bug) */ .popsection -ENTRY(ret_from_kernel_thread) - CFI_STARTPROC - 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(ret_from_kernel_thread) - #ifdef CONFIG_XEN /* Xen doesn't set %esp to be precisely what the normal sysenter entrypoint expects, so fix it up before using the normal path. */ diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 053c9552ffd9..e1f98c22003e 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -459,15 +459,13 @@ ENTRY(ret_from_fork) jmp ret_from_sys_call # go to the SYSRET fastpath 1: - subq $REST_SKIP, %rsp # move the stack pointer back + subq $REST_SKIP, %rsp # leave space for volatiles CFI_ADJUST_CFA_OFFSET REST_SKIP movq %rbp, %rdi call *%rbx - # exit - mov %eax, %edi - call do_exit - ud2 # padding for call trace - + movl $0, RAX(%rsp) + RESTORE_REST + jmp int_ret_from_sys_call CFI_ENDPROC END(ret_from_fork) @@ -1214,20 +1212,6 @@ bad_gs: jmp 2b .previous -ENTRY(ret_from_kernel_execve) - movq %rdi, %rsp - movl $0, RAX(%rsp) - // RESTORE_REST - movq 0*8(%rsp), %r15 - movq 1*8(%rsp), %r14 - movq 2*8(%rsp), %r13 - movq 3*8(%rsp), %r12 - movq 4*8(%rsp), %rbp - movq 5*8(%rsp), %rbx - addq $(6*8), %rsp - jmp int_ret_from_sys_call -END(ret_from_kernel_execve) - /* Call softirq on interrupt stack. Interrupts are off. */ ENTRY(call_softirq) CFI_STARTPROC diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig index da85b6fc8e8e..cab8eb88dd22 100644 --- a/arch/x86/um/Kconfig +++ b/arch/x86/um/Kconfig @@ -14,6 +14,7 @@ config UML_X86 def_bool y select GENERIC_FIND_FIRST_BIT select GENERIC_KERNEL_THREAD + select GENERIC_KERNEL_EXECVE config 64BIT bool "64-bit kernel" if SUBARCH = "x86" -- GitLab