Commit-ID: 42dfc43ee5999ac64284476ea0ac6c937587cf2b Gitweb: http://git.kernel.org/tip/42dfc43ee5999ac64284476ea0ac6c937587cf2b Author: Siddhesh Poyarekar <siddhesh.poyarekar@xxxxxxxxx> AuthorDate: Sun, 26 Feb 2012 21:47:55 +0530 Committer: H. Peter Anvin <hpa@xxxxxxxxx> CommitDate: Sun, 26 Feb 2012 12:59:04 -0800 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@xxxxxxxxx> Link: http://lkml.kernel.org/r/1330273075-2949-1-git-send-email-siddhesh.poyarekar@xxxxxxxxx Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxx> --- 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 1fd94bc..eb54dd0 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); -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
|