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x86, um: convert to saner kernel_execve() semantics

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-10-10 21:35:42 -04:00
parent a74fb73c12
commit 22e2430d60
10 changed files with 21 additions and 68 deletions
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2
arch/um/include/asm/processor-generic.h
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@ -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 } \
}

1
arch/um/include/shared/os.h
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@ -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);

5
arch/um/kernel/exec.c
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@ -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);
}

10
arch/um/kernel/process.c
View File

@ -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, &current->thread.exec_buf);
if (n == 1)
userspace(&current->thread.regs.regs);
else
do_exit(0);
n = fn(arg);
userspace(&current->thread.regs.regs);
}
/* Called magically, see new_thread_handler above */

13
arch/um/os-Linux/process.c
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@ -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;
}

1
arch/x86/Kconfig
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@ -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)

1
arch/x86/include/asm/unistd.h
View File

@ -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

31
arch/x86/kernel/entry_32.S
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@ -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. */

24
arch/x86/kernel/entry_64.S
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@ -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

1
arch/x86/um/Kconfig
View File

@ -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"