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Commit 5e9ebbd8 authored by Alexander Kuleshov's avatar Alexander Kuleshov Committed by Ingo Molnar
Browse files

x86/boot: Micro-optimize reset_early_page_tables() 



Save 25 bytes of code and make the bootup a tiny bit faster:

     text    data bss             dec             filename
  9735144 4970776 15474688        30180608        vmlinux.old
  9735119 4970776 15474688        30180583        vmlinux

Signed-off-by: default avatarAlexander Kuleshov <kuleshovmail@gmail.com>
Cc: Alexander Popov <alpopov@ptsecurity.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
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/1454140872-16926-1-git-send-email-kuleshovmail@gmail.com


[ Fixed various small details. ]
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 26cd8367

arch/x86/kernel/head64.c

+3 −11
Original line number Diff line number Diff line
@@ -40,13 +40,8 @@ pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX); 
/* Wipe all early page tables except for the kernel symbol map */

static void __init reset_early_page_tables(void)

{

	unsigned long i;



	for (i = 0; i < PTRS_PER_PGD-1; i++)

		early_level4_pgt[i].pgd = 0;



	memset(early_level4_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));

	next_early_pgt = 0;



	write_cr3(__pa_nodebug(early_level4_pgt));

}
@@ -54,7 +49,6 @@ static void __init reset_early_page_tables(void) 
int __init early_make_pgtable(unsigned long address)

{

	unsigned long physaddr = address - __PAGE_OFFSET;

	unsigned long i;

	pgdval_t pgd, *pgd_p;

	pudval_t pud, *pud_p;

	pmdval_t pmd, *pmd_p;
@@ -81,8 +75,7 @@ int __init early_make_pgtable(unsigned long address) 
		}



		pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];

		for (i = 0; i < PTRS_PER_PUD; i++)

			pud_p[i] = 0;

		memset(pud_p, 0, sizeof(pud_p) * PTRS_PER_PUD);

		*pgd_p = (pgdval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;

	}

	pud_p += pud_index(address);
@@ -97,8 +90,7 @@ int __init early_make_pgtable(unsigned long address) 
		}



		pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];

		for (i = 0; i < PTRS_PER_PMD; i++)

			pmd_p[i] = 0;

		memset(pmd_p, 0, sizeof(pmd_p) * PTRS_PER_PMD);

		*pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;

	}

	pmd = (physaddr & PMD_MASK) + early_pmd_flags;