[tip:x86/urgent] x86: Mark native_set_p4d() as __always_inline

From: tip-bot for Arnd Bergmann
Date: Wed Jun 06 2018 - 06:14:17 EST

Commit-ID: 046c0dbec0238c25b7526c26c9a9687664229ce2
Gitweb: https://git.kernel.org/tip/046c0dbec0238c25b7526c26c9a9687664229ce2
Author: Arnd Bergmann <arnd@xxxxxxxx>
AuthorDate: Tue, 5 Jun 2018 13:35:15 +0200
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Wed, 6 Jun 2018 12:09:45 +0200

x86: Mark native_set_p4d() as __always_inline

When CONFIG_OPTIMIZE_INLINING is enabled, the function native_set_p4d()
may not be fully inlined into the caller, resulting in a false-positive
warning about an access to the __pgtable_l5_enabled variable from a
non-__init function, despite the original caller being an __init function:

WARNING: vmlinux.o(.text.unlikely+0x1429): Section mismatch in reference from the function native_set_p4d() to the variable .init.data:__pgtable_l5_enabled
WARNING: vmlinux.o(.text.unlikely+0x1429): Section mismatch in reference from the function native_p4d_clear() to the variable .init.data:__pgtable_l5_enabled

The function native_set_p4d() references the variable __initdata
__pgtable_l5_enabled. This is often because native_set_p4d lacks a
__initdata annotation or the annotation of __pgtable_l5_enabled is wrong.

Marking the native_set_p4d function and its caller native_p4d_clear()
avoids this problem.

I did not bisect the original cause, but I assume this is related to the
recent rework that turned pgtable_l5_enabled() into an inline function,
which in turn caused the compiler to make different inlining decisions.

Fixes: ad3fe525b950 ("x86/mm: Unify pgtable_l5_enabled usage in early boot code")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Zi Yan <zi.yan@xxxxxxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20180605113715.1133726-1-arnd@xxxxxxxx

arch/x86/include/asm/pgtable_64.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h
index 877bc27718ae..c750112cb416 100644
--- a/arch/x86/include/asm/pgtable_64.h
+++ b/arch/x86/include/asm/pgtable_64.h
@@ -216,7 +216,7 @@ static inline pgd_t pti_set_user_pgd(pgd_t *pgdp, pgd_t pgd)

-static inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
+static __always_inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
pgd_t pgd;

@@ -230,7 +230,7 @@ static inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
*p4dp = native_make_p4d(native_pgd_val(pgd));

-static inline void native_p4d_clear(p4d_t *p4d)
+static __always_inline void native_p4d_clear(p4d_t *p4d)
native_set_p4d(p4d, native_make_p4d(0));