Messages in this thread Patch in this message | | | From | Brian Gerst <> | Subject | [PATCH 4/4] x86, 64-bit: Use user_mode() to determine new stack pointer in copy_thread() | Date | Fri, 13 Nov 2009 14:54:58 -0500 |
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Use user_mode() instead of a magic value for sp to determine when returning to kernel mode. This simplifies kernel_thread().
Signed-off-by: Brian Gerst <brgerst@gmail.com> --- arch/x86/kernel/process.c | 6 +----- arch/x86/kernel/process_64.c | 5 +++-- 2 files changed, 4 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 71a22c9..4ebe3e4 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -255,7 +255,6 @@ extern void kernel_thread_helper(void); int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) { struct pt_regs regs; - unsigned long newsp; memset(®s, 0, sizeof(regs)); @@ -267,9 +266,6 @@ int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) regs.es = __USER_DS; regs.fs = __KERNEL_PERCPU; regs.gs = __KERNEL_STACK_CANARY; - newsp = 0; -#else - newsp = ~0UL; #endif regs.orig_ax = -1; @@ -278,7 +274,7 @@ int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags) regs.flags = X86_EFLAGS_IF | 2; /* Ok, create the new process.. */ - return do_fork(flags | CLONE_VM | CLONE_UNTRACED, newsp, ®s, 0, NULL, NULL); + return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL); } EXPORT_SYMBOL(kernel_thread); diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 8151a82..a9be0d5 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -283,8 +283,9 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, *childregs = *regs; childregs->ax = 0; - childregs->sp = sp; - if (sp == ~0UL) + if (user_mode(regs)) + childregs->sp = sp; + else childregs->sp = (unsigned long)childregs; p->thread.sp = (unsigned long) childregs; -- 1.6.2.5
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