diff options
Diffstat (limited to 'debian/patches-rt/0226-x86-stackprotector-Avoid-random-pool-on-rt.patch')
| -rw-r--r-- | debian/patches-rt/0226-x86-stackprotector-Avoid-random-pool-on-rt.patch | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/debian/patches-rt/0226-x86-stackprotector-Avoid-random-pool-on-rt.patch b/debian/patches-rt/0226-x86-stackprotector-Avoid-random-pool-on-rt.patch new file mode 100644 index 000000000..f9db1d99d --- /dev/null +++ b/debian/patches-rt/0226-x86-stackprotector-Avoid-random-pool-on-rt.patch @@ -0,0 +1,51 @@ +From b70b05c554fb10c5bccff5b27a1d5ed73d054313 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Thu, 16 Dec 2010 14:25:18 +0100 +Subject: [PATCH 226/347] x86: stackprotector: Avoid random pool on rt +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.246-rt110.tar.xz + +CPU bringup calls into the random pool to initialize the stack +canary. During boot that works nicely even on RT as the might sleep +checks are disabled. During CPU hotplug the might sleep checks +trigger. Making the locks in random raw is a major PITA, so avoid the +call on RT is the only sensible solution. This is basically the same +randomness which we get during boot where the random pool has no +entropy and we rely on the TSC randomnness. + +Reported-by: Carsten Emde <carsten.emde@osadl.org> +Signed-off-by: Thomas Gleixner <tglx@linutronix.de> +--- + arch/x86/include/asm/stackprotector.h | 8 +++++++- + 1 file changed, 7 insertions(+), 1 deletion(-) + +diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h +index 9c556ea2eaa7..b136992beb1b 100644 +--- a/arch/x86/include/asm/stackprotector.h ++++ b/arch/x86/include/asm/stackprotector.h +@@ -65,7 +65,7 @@ + */ + static __always_inline void boot_init_stack_canary(void) + { +- u64 canary; ++ u64 uninitialized_var(canary); + u64 tsc; + + #ifdef CONFIG_X86_64 +@@ -76,8 +76,14 @@ static __always_inline void boot_init_stack_canary(void) + * of randomness. The TSC only matters for very early init, + * there it already has some randomness on most systems. Later + * on during the bootup the random pool has true entropy too. ++ * For preempt-rt we need to weaken the randomness a bit, as ++ * we can't call into the random generator from atomic context ++ * due to locking constraints. We just leave canary ++ * uninitialized and use the TSC based randomness on top of it. + */ ++#ifndef CONFIG_PREEMPT_RT_FULL + get_random_bytes(&canary, sizeof(canary)); ++#endif + tsc = rdtsc(); + canary += tsc + (tsc << 32UL); + canary &= CANARY_MASK; +-- +2.36.1 + |