[GIT PULL] x86 fixes

Ingo Molnar
2018-07-30T18:00:02Z

Linus,

Please pull the latest x86-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-for-linus

# HEAD: 92a4728608a8fd228c572bc8ff50dd98aa0ddf2a x86/boot: Fix if_changed build flip/flop bug

Misc fixes:

- a build race fix
- a Xen entry fix
- a TSC_DEADLINE quirk future-proofing fix

Thanks,

Ingo

------------------>
Andy Lutomirski (1):
x86/entry/64: Remove %ebx handling from error_entry/exit

Kees Cook (1):
x86/boot: Fix if_changed build flip/flop bug

Len Brown (1):
x86/apic: Future-proof the TSC_DEADLINE quirk for SKX

arch/x86/boot/compressed/Makefile | 8 ++++++--
arch/x86/entry/entry_64.S | 18 ++++--------------
arch/x86/kernel/apic/apic.c | 3 +++
3 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index fa42f895fdde..169c2feda14a 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -106,9 +106,13 @@ define cmd_check_data_rel
done
endef

+# We need to run two commands under "if_changed", so merge them into a
+# single invocation.
+quiet_cmd_check-and-link-vmlinux = LD $@
+ cmd_check-and-link-vmlinux = $(cmd_check_data_rel); $(cmd_ld)
+
$(obj)/vmlinux: $(vmlinux-objs-y) FORCE
- $(call if_changed,check_data_rel)
- $(call if_changed,ld)
+ $(call if_changed,check-and-link-vmlinux)

OBJCOPYFLAGS_vmlinux.bin := -R .comment -S
$(obj)/vmlinux.bin: vmlinux FORCE
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 73a522d53b53..8ae7ffda8f98 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -981,7 +981,7 @@ ENTRY(\sym)

call \do_sym

- jmp error_exit /* %ebx: no swapgs flag */
+ jmp error_exit
.endif
END(\sym)
.endm
@@ -1222,7 +1222,6 @@ END(paranoid_exit)

/*
* Save all registers in pt_regs, and switch GS if needed.
- * Return: EBX=0: came from user mode; EBX=1: otherwise
*/
ENTRY(error_entry)
UNWIND_HINT_FUNC
@@ -1269,7 +1268,6 @@ ENTRY(error_entry)
* for these here too.
*/
.Lerror_kernelspace:
- incl %ebx
leaq native_irq_return_iret(%rip), %rcx
cmpq %rcx, RIP+8(%rsp)
je .Lerror_bad_iret
@@ -1303,28 +1301,20 @@ ENTRY(error_entry)

/*
* Pretend that the exception came from user mode: set up pt_regs
- * as if we faulted immediately after IRET and clear EBX so that
- * error_exit knows that we will be returning to user mode.
+ * as if we faulted immediately after IRET.
*/
mov %rsp, %rdi
call fixup_bad_iret
mov %rax, %rsp
- decl %ebx
jmp .Lerror_entry_from_usermode_after_swapgs
END(error_entry)

-
-/*
- * On entry, EBX is a "return to kernel mode" flag:
- * 1: already in kernel mode, don't need SWAPGS
- * 0: user gsbase is loaded, we need SWAPGS and standard preparation for return to usermode
- */
ENTRY(error_exit)
UNWIND_HINT_REGS
DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
- testl %ebx, %ebx
- jnz retint_kernel
+ testb $3, CS(%rsp)
+ jz retint_kernel
jmp retint_user
END(error_exit)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 2aabd4cb0e3f..adbda5847b14 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -573,6 +573,9 @@ static u32 skx_deadline_rev(void)
case 0x04: return 0x02000014;
}

+ if (boot_cpu_data.x86_stepping > 4)
+ return 0;
+
return ~0U;
}