linux-kernel - [tip:x86/urgent] Revert "x86/mm: Mark __pgtable_l5_enabled _

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Date:   Sat, 23 Jun 2018 05:30:48 -0700
From:   "tip-bot for Kirill A. Shutemov" <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        kirill.shutemov@...ux.intel.com, mingo@...nel.org, hpa@...or.com
Subject: [tip:x86/urgent] Revert "x86/mm: Mark __pgtable_l5_enabled
 __initdata"

Commit-ID:  51be1335151771075dcb19f3464ca9f331134285
Gitweb:     https://git.kernel.org/tip/51be1335151771075dcb19f3464ca9f331134285
Author:     Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
AuthorDate: Sat, 23 Jun 2018 01:08:40 +0300
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Sat, 23 Jun 2018 14:20:37 +0200

Revert "x86/mm: Mark __pgtable_l5_enabled __initdata"

This reverts commit e4e961e36f063484c48bed919013c106d178995d.

We need to use early version of pgtable_l5_enabled() in
early_identify_cpu() as this code runs before cpu_feature_enabled() is
usable.

But it leads to section mismatch:

cpu_init()
  load_mm_ldt()
    ldt_slot_va()
      LDT_BASE_ADDR
        LDT_PGD_ENTRY
	  pgtable_l5_enabled()
	    __pgtable_l5_enabled

__pgtable_l5_enabled marked as __initdata, but cpu_init() is not __init.

It's fixable: early code can be isolated into a separate translation unit,
but such change collides with other work in the area.  That's too much
hassle to save 4 bytes of memory.

Return __pgtable_l5_enabled back to be __ro_after_init.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Link: https://lkml.kernel.org/r/20180622220841.54135-2-kirill.shutemov@linux.intel.com

---
 arch/x86/kernel/head64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index a21d6ace648e..8047379e575a 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -44,7 +44,7 @@ static unsigned int __initdata next_early_pgt;
 pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);

 #ifdef CONFIG_X86_5LEVEL
-unsigned int __pgtable_l5_enabled __initdata;
+unsigned int __pgtable_l5_enabled __ro_after_init;
 unsigned int pgdir_shift __ro_after_init = 39;
 EXPORT_SYMBOL(pgdir_shift);
 unsigned int ptrs_per_p4d __ro_after_init = 1;