From: Kristen Carlson Accardi <kristen@linux.intel.com>
To: keescook@chromium.org, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Cc: arjan@linux.intel.com, linux-kernel@vger.kernel.org,
kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com,
Kristen Carlson Accardi <kristen@linux.intel.com>
Subject: [PATCH v5 02/10] x86/boot: Allow a "silent" kaslr random byte fetch
Date: Wed, 23 Sep 2020 10:38:56 -0700 [thread overview]
Message-ID: <20200923173905.11219-3-kristen@linux.intel.com> (raw)
In-Reply-To: <20200923173905.11219-1-kristen@linux.intel.com>
From: Kees Cook <keescook@chromium.org>
Under earlyprintk, each RNG call produces a debug report line. When
shuffling hundreds of functions, this is not useful information (each
line is identical and tells us nothing new). Instead, allow for a NULL
"purpose" to suppress the debug reporting.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
---
arch/x86/lib/kaslr.c | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/arch/x86/lib/kaslr.c b/arch/x86/lib/kaslr.c
index a53665116458..2b3eb8c948a3 100644
--- a/arch/x86/lib/kaslr.c
+++ b/arch/x86/lib/kaslr.c
@@ -56,11 +56,14 @@ unsigned long kaslr_get_random_long(const char *purpose)
unsigned long raw, random = get_boot_seed();
bool use_i8254 = true;
- debug_putstr(purpose);
- debug_putstr(" KASLR using");
+ if (purpose) {
+ debug_putstr(purpose);
+ debug_putstr(" KASLR using");
+ }
if (has_cpuflag(X86_FEATURE_RDRAND)) {
- debug_putstr(" RDRAND");
+ if (purpose)
+ debug_putstr(" RDRAND");
if (rdrand_long(&raw)) {
random ^= raw;
use_i8254 = false;
@@ -68,7 +71,8 @@ unsigned long kaslr_get_random_long(const char *purpose)
}
if (has_cpuflag(X86_FEATURE_TSC)) {
- debug_putstr(" RDTSC");
+ if (purpose)
+ debug_putstr(" RDTSC");
raw = rdtsc();
random ^= raw;
@@ -76,7 +80,8 @@ unsigned long kaslr_get_random_long(const char *purpose)
}
if (use_i8254) {
- debug_putstr(" i8254");
+ if (purpose)
+ debug_putstr(" i8254");
random ^= i8254();
}
@@ -86,7 +91,8 @@ unsigned long kaslr_get_random_long(const char *purpose)
: "a" (random), "rm" (mix_const));
random += raw;
- debug_putstr("...\n");
+ if (purpose)
+ debug_putstr("...\n");
return random;
}
--
2.20.1
next parent reply other threads:[~2020-09-23 17:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200923173905.11219-1-kristen@linux.intel.com>
2020-09-23 17:38 ` Kristen Carlson Accardi [this message]
2020-09-23 17:38 ` [PATCH v5 03/10] x86: Makefile: Add build and config option for CONFIG_FG_KASLR Kristen Carlson Accardi
2020-09-23 17:38 ` [PATCH v5 04/10] x86: Make sure _etext includes function sections Kristen Carlson Accardi
2020-09-23 17:39 ` [PATCH v5 06/10] x86/boot/compressed: Avoid duplicate malloc() implementations Kristen Carlson Accardi
2020-09-23 17:39 ` [PATCH v5 10/10] livepatch: only match unique symbols when using fgkaslr Kristen Carlson Accardi
2020-09-24 13:06 ` Miroslav Benes
2020-09-25 13:06 ` [PATCH v5 00/10] Function Granular KASLR Miroslav Benes
2020-09-28 17:31 ` Kristen Carlson Accardi
2020-09-29 18:58 ` Kees Cook
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