linux-kernel - [tip: x86/kaslr] x86/kaslr: Drop test for command-line parameters before parsing

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Date:   Thu, 06 Aug 2020 23:38:55 -0000
From:   "tip-bot2 for Arvind Sankar" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Arvind Sankar <nivedita@...m.mit.edu>,
        Ingo Molnar <mingo@...nel.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: x86/kaslr] x86/kaslr: Drop test for command-line parameters
 before parsing

The following commit has been merged into the x86/kaslr branch of tip:

Commit-ID:     3870d971791f13df88a7a656e3fd6e2df8686097
Gitweb:        https://git.kernel.org/tip/3870d971791f13df88a7a656e3fd6e2df8686097
Author:        Arvind Sankar <nivedita@...m.mit.edu>
AuthorDate:    Tue, 28 Jul 2020 18:57:14 -04:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 31 Jul 2020 11:08:17 +02:00

x86/kaslr: Drop test for command-line parameters before parsing

This check doesn't save anything. In the case when none of the
parameters are present, each strstr will scan args twice (once to find
the length and then for searching), six scans in total. Just going ahead
and parsing the arguments only requires three scans: strlen, memcpy, and
parsing. This will be the first malloc, so free will actually free up
the memory, so the check doesn't save heap space either.

Signed-off-by: Arvind Sankar <nivedita@...m.mit.edu>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Link: https://lore.kernel.org/r/20200728225722.67457-14-nivedita@alum.mit.edu
---
 arch/x86/boot/compressed/kaslr.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 00ef84b..bd13dc5 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -279,10 +279,6 @@ static void handle_mem_options(void)
 	if (!args)
 		return;
 
-	if (!strstr(args, "memmap=") && !strstr(args, "mem=") &&
-		!strstr(args, "hugepages"))
-		return;
-
 	len = strlen(args);
 	tmp_cmdline = malloc(len + 1);
 	if (!tmp_cmdline)