4.14-stable review patch. If anyone has any objections, please let me know.
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From: Andy Lutomirski luto@kernel.org
commit 26c4ef9c49d8a0341f6d97ce2cfdd55d1236ed29 upstream.
These code paths will diverge soon.
Signed-off-by: Andy Lutomirski luto@kernel.org Cc: Borislav Petkov bpetkov@suse.de Cc: Brian Gerst brgerst@gmail.com Cc: Dave Hansen dave.hansen@intel.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Link: http://lkml.kernel.org/r/dccf8c7b3750199b4b30383c812d4e2931811509.1509609304... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/entry/entry_64.S | 34 +++++++++++++++++++++++++--------- arch/x86/entry/entry_64_compat.S | 2 +- arch/x86/kernel/head_64.S | 2 +- 3 files changed, 27 insertions(+), 11 deletions(-)
--- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -322,7 +322,7 @@ syscall_return_via_sysret:
opportunistic_sysret_failed: SWAPGS - jmp restore_regs_and_iret + jmp restore_regs_and_return_to_usermode END(entry_SYSCALL_64)
ENTRY(stub_ptregs_64) @@ -424,7 +424,7 @@ ENTRY(ret_from_fork) call syscall_return_slowpath /* returns with IRQs disabled */ TRACE_IRQS_ON /* user mode is traced as IRQS on */ SWAPGS - jmp restore_regs_and_iret + jmp restore_regs_and_return_to_usermode
1: /* kernel thread */ @@ -613,7 +613,20 @@ GLOBAL(retint_user) call prepare_exit_to_usermode TRACE_IRQS_IRETQ SWAPGS - jmp restore_regs_and_iret + +GLOBAL(restore_regs_and_return_to_usermode) +#ifdef CONFIG_DEBUG_ENTRY + /* Assert that pt_regs indicates user mode. */ + testl $3, CS(%rsp) + jnz 1f + ud2 +1: +#endif + RESTORE_EXTRA_REGS + RESTORE_C_REGS + REMOVE_PT_GPREGS_FROM_STACK 8 + INTERRUPT_RETURN +
/* Returning to kernel space */ retint_kernel: @@ -633,11 +646,14 @@ retint_kernel: */ TRACE_IRQS_IRETQ
-/* - * At this label, code paths which return to kernel and to user, - * which come from interrupts/exception and from syscalls, merge. - */ -GLOBAL(restore_regs_and_iret) +GLOBAL(restore_regs_and_return_to_kernel) +#ifdef CONFIG_DEBUG_ENTRY + /* Assert that pt_regs indicates kernel mode. */ + testl $3, CS(%rsp) + jz 1f + ud2 +1: +#endif RESTORE_EXTRA_REGS RESTORE_C_REGS REMOVE_PT_GPREGS_FROM_STACK 8 @@ -1328,7 +1344,7 @@ ENTRY(nmi) * work, because we don't want to enable interrupts. */ SWAPGS - jmp restore_regs_and_iret + jmp restore_regs_and_return_to_usermode
.Lnmi_from_kernel: /* --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -338,7 +338,7 @@ ENTRY(entry_INT80_compat) /* Go back to user mode. */ TRACE_IRQS_ON SWAPGS - jmp restore_regs_and_iret + jmp restore_regs_and_return_to_usermode END(entry_INT80_compat)
ENTRY(stub32_clone) --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -328,7 +328,7 @@ early_idt_handler_common:
20: decl early_recursion_flag(%rip) - jmp restore_regs_and_iret + jmp restore_regs_and_return_to_kernel END(early_idt_handler_common)
__INITDATA