linux-kernel - [tip:x86/boot] x86/boot: Use proper array element type in memset( ) size calculation

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Message-ID: <tip-a91bbe017552b80e12d712c85549b933a62c6ed4@git.kernel.org>
Date:	Tue, 9 Feb 2016 08:09:34 -0800
From:	tip-bot for Alexander Kuleshov <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	andriy.shevchenko@...ux.intel.com, hpa@...or.com, mingo@...nel.org,
	alpopov@...ecurity.com, luto@...nel.org,
	linux-kernel@...r.kernel.org, peterz@...radead.org,
	ryabinin.a.a@...il.com, kuleshovmail@...il.com,
	torvalds@...ux-foundation.org, tglx@...utronix.de
Subject: [tip:x86/boot] x86/boot: Use proper array element type in memset(
 ) size calculation

Commit-ID:  a91bbe017552b80e12d712c85549b933a62c6ed4
Gitweb:     http://git.kernel.org/tip/a91bbe017552b80e12d712c85549b933a62c6ed4
Author:     Alexander Kuleshov <kuleshovmail@...il.com>
AuthorDate: Tue, 9 Feb 2016 19:44:54 +0600
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 9 Feb 2016 14:55:48 +0100

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 <kuleshovmail@...il.com>
Cc: Alexander Popov <alpopov@...ecurity.com>
Cc: Andrey Ryabinin <ryabinin.a.a@...il.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/1455025494-4063-1-git-send-email-kuleshovmail@gmail.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/head64.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 35843ca..7793a17 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;