diff options
| author | Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com> | 2012-02-26 21:47:55 +0530 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2012-02-26 12:59:04 -0800 |
| commit | 42dfc43ee5999ac64284476ea0ac6c937587cf2b (patch) | |
| tree | 4527353aa4f9cfedc09142f2a9da418c90b618e5 /arch/x86/kernel/process_64.c | |
| parent | b01543dfe67bb1d191998e90d20534dc354de059 (diff) | |
x86_64: Record stack pointer before task execution begins
task->thread.usersp is unusable immediately after a binary is exec()'d
until it undergoes a context switch cycle. The start_thread() function
called during execve() saves the stack pointer into pt_regs and into
old_rsp, but fails to record it into task->thread.usersp.
Because of this, KSTK_ESP(task) returns an incorrect value for a
64-bit program until the task is switched out and back in since
switch_to swaps %rsp values in and out into task->thread.usersp.
Signed-off-by: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com>
Link: http://lkml.kernel.org/r/1330273075-2949-1-git-send-email-siddhesh.poyarekar@gmail.com
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch/x86/kernel/process_64.c')
| -rw-r--r-- | arch/x86/kernel/process_64.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 1fd94bc4279d..eb54dd0fbed6 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -341,6 +341,7 @@ start_thread_common(struct pt_regs *regs, unsigned long new_ip, loadsegment(es, _ds); loadsegment(ds, _ds); load_gs_index(0); + current->thread.usersp = new_sp; regs->ip = new_ip; regs->sp = new_sp; percpu_write(old_rsp, new_sp); |