[tip:x86/cpu] x86/cpu: Trim model ID whitespace

[tip-bot for Borislav Petkov]

Commit-ID:  ee098e1aed67715f0ce4651813d0c33ab3a56e0b
Gitweb:     http://git.kernel.org/tip/ee098e1aed67715f0ce4651813d0c33ab3a56e0b
Author:     Borislav Petkov <bp@xxxxxxx>
AuthorDate: Mon, 1 Jun 2015 12:06:57 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 2 Jun 2015 10:38:11 +0200

x86/cpu: Trim model ID whitespace

We did try trimming whitespace surrounding the 'model name'
field in /proc/cpuinfo since reportedly some userspace uses it
in string comparisons and there were discrepancies:

  [thetango@prarit ~]# grep "^model name" /proc/cpuinfo | uniq -c | sed 's/\ /_/g'
  ______1_model_name      :_AMD_Opteron(TM)_Processor_6272
  _____63_model_name      :_AMD_Opteron(TM)_Processor_6272_________________

However, there were issues with overlapping buffers, string
sizes and non-byte-sized copies in the previous proposed
solutions; see Link tags below for the whole farce.

So, instead of diddling with this more, let's simply extend what
was there originally with trimming any present trailing
whitespace. Final result is really simple and obvious.

Testing with the most insane model IDs qemu can generate, looks
good:

  .model_id = "            My funny model ID CPU          ",
  ______4_model_name      :_My_funny_model_ID_CPU

  .model_id = "My funny model ID CPU          ",
  ______4_model_name      :_My_funny_model_ID_CPU

  .model_id = "            My funny model ID CPU",
  ______4_model_name      :_My_funny_model_ID_CPU

  .model_id = "            ",
  ______4_model_name      :__

  .model_id = "",
  ______4_model_name      :_15/02

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Igor Mammedov <imammedo@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1432050210-32036-1-git-send-email-prarit@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/kernel/cpu/common.c | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 41a8e9c..351197c 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -5,6 +5,7 @@
 #include <linux/module.h>
 #include <linux/percpu.h>
 #include <linux/string.h>
+#include <linux/ctype.h>
 #include <linux/delay.h>
 #include <linux/sched.h>
 #include <linux/init.h>
@@ -419,6 +420,7 @@ static const struct cpu_dev *cpu_devs[X86_VENDOR_NUM] = {};
 static void get_model_name(struct cpuinfo_x86 *c)
 {
 	unsigned int *v;
+	char *p, *q, *s;
 
 	if (c->extended_cpuid_level < 0x80000004)
 		return;
@@ -429,11 +431,21 @@ static void get_model_name(struct cpuinfo_x86 *c)
 	cpuid(0x80000004, &v[8], &v[9], &v[10], &v[11]);
 	c->x86_model_id[48] = 0;
 
-	/*
-	 * Remove leading whitespace on Intel processors and trailing
-	 * whitespace on AMD processors.
-	 */
-	memmove(c->x86_model_id, strim(c->x86_model_id), 48);
+	/* Trim whitespace */
+	p = q = s = &c->x86_model_id[0];
+
+	while (*p == ' ')
+		p++;
+
+	while (*p) {
+		/* Note the last non-whitespace index */
+		if (!isspace(*p))
+			s = q;
+
+		*q++ = *p++;
+	}
+
+	*(s + 1) = '\0';
 }
 
 void cpu_detect_cache_sizes(struct cpuinfo_x86 *c)
--
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