From 5e9ebbd87a99ecc6abb74325b0ac63c46891f6f3 Mon Sep 17 00:00:00 2001 From: Alexander Kuleshov Date: Sat, 30 Jan 2016 14:01:12 +0600 Subject: 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: Alexander Kuleshov Cc: Alexander Popov Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1454140872-16926-1-git-send-email-kuleshovmail@gmail.com [ Fixed various small details. ] Signed-off-by: Ingo Molnar --- arch/x86/kernel/head64.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) (limited to 'arch/x86/kernel/head64.c') diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index f129a9af6357..35843caa4ea7 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -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 @@ again: } 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 @@ again: } 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; -- cgit v1.2.3 From a91bbe017552b80e12d712c85549b933a62c6ed4 Mon Sep 17 00:00:00 2001 From: Alexander Kuleshov Date: Tue, 9 Feb 2016 19:44:54 +0600 Subject: x86/boot: Use proper array element type in memset() size calculation I changed open coded zeroing loops to explicit memset()s in the following commit: 5e9ebbd87a99 ("x86/boot: Micro-optimize reset_early_page_tables()") The base for the size argument of memset was sizeof(pud_p/pmd_p), which are pointers - but the initialized array has pud_t/pmd_t elements. Luckily the two types had the same size, so this did not result in any runtime misbehavior. Signed-off-by: Alexander Kuleshov Cc: Alexander Popov Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Andy Shevchenko Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1455025494-4063-1-git-send-email-kuleshovmail@gmail.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/head64.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/kernel/head64.c') diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 35843caa4ea7..7793a1702204 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -75,7 +75,7 @@ again: } pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++]; - memset(pud_p, 0, sizeof(pud_p) * PTRS_PER_PUD); + 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); @@ -90,7 +90,7 @@ again: } pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++]; - memset(pmd_p, 0, sizeof(pmd_p) * PTRS_PER_PMD); + 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; -- cgit v1.2.3