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authorSteven Rostedt <srostedt@redhat.com>2014-02-06 09:41:30 -0500
committerH. Peter Anvin <hpa@linux.intel.com>2014-03-06 16:56:54 -0800
commit0788aa6a23cb9d693fc5040ec774b979f1e906cd (patch)
treeb1c5fd2dab9c0e11bc1747e5f6102d89d16dfcc0 /arch/x86/kernel/ptrace.c
parentb807902a88c470eb06d0acdf3b6590f27f5dce81 (diff)
x86: Prepare removal of previous_esp from i386 thread_info structure
The i386 thread_info contains a previous_esp field that is used to daisy chain the different stacks for dump_stack() (ie. irq, softirq, thread stacks). The goal is to eventual make i386 handling of thread_info the same as x86_64, which means that the thread_info will not be in the stack but as a per_cpu variable. We will no longer depend on thread_info being able to daisy chain different stacks as it will only exist in one location (the thread stack). By moving previous_esp to the end of thread_info and referencing it as an offset instead of using a thread_info field, this becomes a stepping stone to moving the thread_info. The offset to get to the previous stack is rather ugly in this patch, but this is only temporary and the prev_esp will be changed in the next commit. This commit is more for sanity checks of the change. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Robert Richter <rric@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Link: http://lkml.kernel.org/r/20110806012353.891757693@goodmis.org Link: http://lkml.kernel.org/r/20140206144321.608754481@goodmis.org Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Diffstat (limited to 'arch/x86/kernel/ptrace.c')
-rw-r--r--arch/x86/kernel/ptrace.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 7461f50d5bb1..f352a7cc43a1 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -184,14 +184,14 @@ unsigned long kernel_stack_pointer(struct pt_regs *regs)
{
unsigned long context = (unsigned long)regs & ~(THREAD_SIZE - 1);
unsigned long sp = (unsigned long)&regs->sp;
- struct thread_info *tinfo;
+ u32 *prev_esp;
if (context == (sp & ~(THREAD_SIZE - 1)))
return sp;
- tinfo = (struct thread_info *)context;
- if (tinfo->previous_esp)
- return tinfo->previous_esp;
+ prev_esp = (u32 *)(context + sizeof(struct thread_info) - sizeof(long));
+ if (prev_esp)
+ return (unsigned long)prev_esp;
return (unsigned long)regs;
}