Commit-ID: 33db1fd48ac3d90385b412b41a8a6525096ac6d5 Gitweb: http://git.kernel.org/tip/33db1fd48ac3d90385b412b41a8a6525096ac6d5 Author: Denys Vlasenko <[email protected]> AuthorDate: Tue, 17 Mar 2015 14:52:24 +0100 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 17 Mar 2015 16:01:40 +0100
x86/asm/entry/64: Enable interrupts *after* we fetch PER_CPU_VAR(old_rsp) We want to use PER_CPU_VAR(old_rsp) as a simple temporary register, to shuffle user-space RSP into (and from) when we set up the system call stack frame. At that point we cannot shuffle values into general purpose registers, because we have not saved them yet. To be able to do this shuffling into a memory location, we must be atomic and must not be preempted while we do the shuffling, otherwise the 'temporary' register gets overwritten by some other task's temporary register contents ... Tested-by: Borislav Petkov <[email protected]> Signed-off-by: Denys Vlasenko <[email protected]> Acked-by: Borislav Petkov <[email protected]> Cc: Alexei Starovoitov <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Frederic Weisbecker <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Kees Cook <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Steven Rostedt <[email protected]> Cc: Will Drewry <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/kernel/entry_64.S | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index d86788c..aed3f11 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -241,16 +241,16 @@ GLOBAL(system_call_after_swapgs) movq %rsp,PER_CPU_VAR(old_rsp) /* kernel_stack is set so that 5 slots (iret frame) are preallocated */ movq PER_CPU_VAR(kernel_stack),%rsp - /* - * No need to follow this irqs off/on section - it's straight - * and short: - */ - ENABLE_INTERRUPTS(CLBR_NONE) ALLOC_PT_GPREGS_ON_STACK 8 /* +8: space for orig_ax */ movq %rcx,RIP(%rsp) movq PER_CPU_VAR(old_rsp),%rcx movq %r11,EFLAGS(%rsp) movq %rcx,RSP(%rsp) + /* + * No need to follow this irqs off/on section - it's straight + * and short: + */ + ENABLE_INTERRUPTS(CLBR_NONE) movq_cfi rax,ORIG_RAX SAVE_C_REGS_EXCEPT_RAX_RCX_R11 movq $-ENOSYS,RAX(%rsp) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
