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Subject[PATCH 2/5] x86, 64-bit: Use user_mode() to determine new stack pointer in copy_thread()
Date
Use user_mode() instead of a magic value for sp to determine when returning
to kernel mode.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
---
arch/x86/kernel/process_64.c | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 866b4b4..1d8b03d 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -254,7 +254,7 @@ int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
regs.flags = X86_EFLAGS_IF;

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

@@ -312,8 +312,9 @@ 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;
--
1.6.5.2


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