From: Hugh Dickins hughd@google.com
pjt has observed that nmi's second (nmi_from_kernel) call to do_nmi() adjusted the %rdi regs arg, rightly when CONFIG_KAISER, but wrongly when not CONFIG_KAISER.
Although the minimal change is to add an #ifdef CONFIG_KAISER around the addq line, that looks cluttered, and I prefer how the first call to do_nmi() handled it: prepare args in %rdi and %rsi before getting into the CONFIG_KAISER block, since it does not touch them at all.
And while we're here, place the "#ifdef CONFIG_KAISER" that follows each, to enclose the "Unconditionally restore CR3" comment: matching how the "Unconditionally use kernel CR3" comment above is enclosed.
Signed-off-by: Hugh Dickins hughd@google.com Acked-by: Jiri Kosina jkosina@suse.cz Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org (cherry picked from commit 487f0b73d82611a2dc48d7d78409e2e9d994006a) Signed-off-by: Pavel Tatashin pasha.tatashin@oracle.com
Conflicts: arch/x86/entry/entry_64.S (not in this tree) arch/x86/kernel/entry_64.S (patched instead of that) --- arch/x86/kernel/entry_64.S | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 1bda5ebd1013..8e4056d4b1d6 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -1547,12 +1547,12 @@ ENTRY(nmi) movq %rax, %cr3 #endif call do_nmi +#ifdef CONFIG_KAISER /* * Unconditionally restore CR3. I know we return to * kernel code that needs user CR3, but do we ever return * to "user mode" where we need the kernel CR3? */ -#ifdef CONFIG_KAISER popq %rax mov %rax, %cr3 #endif @@ -1772,6 +1772,8 @@ end_repeat_nmi: SWAPGS xorl %ebx, %ebx 1: + movq %rsp, %rdi + movq $-1, %rsi #ifdef CONFIG_KAISER /* Unconditionally use kernel CR3 for do_nmi() */ /* %rax is saved above, so OK to clobber here */ @@ -1785,16 +1787,13 @@ end_repeat_nmi: DEFAULT_FRAME 0 /* XXX: Do we need this? */
/* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */ - movq %rsp,%rdi - addq $8, %rdi /* point %rdi at ptregs, fixed up for CR3 */ - movq $-1,%rsi call do_nmi +#ifdef CONFIG_KAISER /* * Unconditionally restore CR3. We might be returning to * kernel code that needs user CR3, like just just before * a sysret. */ -#ifdef CONFIG_KAISER popq %rax mov %rax, %cr3 #endif