Will Deacon 0ead6914dc arm64: spectre: Prevent lockdep splat on v4 mitigation enable path ... commit a2c42bbabb upstream. The Spectre-v4 workaround is re-configured when resuming from suspend, as the firmware may have re-enabled the mitigation despite the user previously asking for it to be disabled. Enabling or disabling the workaround can result in an undefined instruction exception on CPUs which implement PSTATE.SSBS but only allow it to be configured by adjusting the SPSR on exception return. We handle this by installing an 'undef hook' which effectively emulates the access. Installing this hook requires us to take a couple of spinlocks both to avoid corrupting the internal list of hooks but also to ensure that we don't run into an unhandled exception. Unfortunately, when resuming from suspend, we haven't yet called rcu_idle_exit() and so lockdep gets angry about "suspicious RCU usage". In doing so, it tries to print a warning, which leads it to get even more suspicious, this time about itself: | rcu_scheduler_active = 2, debug_locks = 1 | RCU used illegally from extended quiescent state! | 1 lock held by swapper/0: | #0: (logbuf_lock){-.-.}-{2:2}, at: vprintk_emit+0x88/0x198 | | Call trace: | dump_backtrace+0x0/0x1d8 | show_stack+0x18/0x24 | dump_stack+0xe0/0x17c | lockdep_rcu_suspicious+0x11c/0x134 | trace_lock_release+0xa0/0x160 | lock_release+0x3c/0x290 | _raw_spin_unlock+0x44/0x80 | vprintk_emit+0xbc/0x198 | vprintk_default+0x44/0x6c | vprintk_func+0x1f4/0x1fc | printk+0x54/0x7c | lockdep_rcu_suspicious+0x30/0x134 | trace_lock_acquire+0xa0/0x188 | lock_acquire+0x50/0x2fc | _raw_spin_lock+0x68/0x80 | spectre_v4_enable_mitigation+0xa8/0x30c | __cpu_suspend_exit+0xd4/0x1a8 | cpu_suspend+0xa0/0x104 | psci_cpu_suspend_enter+0x3c/0x5c | psci_enter_idle_state+0x44/0x74 | cpuidle_enter_state+0x148/0x2f8 | cpuidle_enter+0x38/0x50 | do_idle+0x1f0/0x2b4 Prevent these splats by running __cpu_suspend_exit() with RCU watching. Cc: Mark Rutland <mark.rutland@arm.com> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Saravana Kannan <saravanak@google.com> Suggested-by: "Paul E . McKenney" <paulmck@kernel.org> Reported-by: Sami Tolvanen <samitolvanen@google.com> Fixes: c28762070c ("arm64: Rewrite Spectre-v4 mitigation code") Cc: <stable@vger.kernel.org> Acked-by: Paul E. McKenney <paulmck@kernel.org> Acked-by: Marc Zyngier <maz@kernel.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/r/20210218140346.5224-1-will@kernel.org Signed-off-by: Will Deacon <will@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2021-03-04 11:38:36 +01:00
..
boot	arm64: dts: agilex: fix phy interface bit shift for gmac1 and gmac2	2021-03-04 11:38:33 +01:00
configs	arm64: defconfig: Build in CONFIG_GPIO_MXC by default	2020-10-26 15:48:58 +08:00
crypto	crypto: arm64/sha - add missing module aliases	2021-03-04 11:38:31 +01:00
include	arm64 module: set plt* section addresses to 0x0	2021-03-04 11:38:36 +01:00
kernel	arm64: spectre: Prevent lockdep splat on v4 mitigation enable path	2021-03-04 11:38:36 +01:00
kvm	KVM: arm64: Filter out v8.1+ events on v8.0 HW	2021-02-03 23:28:41 +01:00
lib	arm64: Change .weak to SYM_FUNC_START_WEAK_PI for arch/arm64/lib/mem*.S	2020-10-30 08:32:31 +00:00
mm	arm64: Do not pass tagged addresses to __is_lm_address()	2021-02-07 15:37:13 +01:00
net	arm64: bpf: Fix branch offset in JIT	2020-09-17 12:05:36 +01:00
xen
Kbuild
Kconfig	arm64: Extend workaround for erratum 1024718 to all versions of Cortex-A55	2021-03-04 11:38:35 +01:00
Kconfig.debug	arm64: remove TEXT_OFFSET randomization	2020-06-15 13:10:59 +01:00
Kconfig.platforms	arm64: berlin: Select DW_APB_TIMER_OF	2020-10-26 10:45:03 +01:00
Makefile	arm64: link with -z norelro for LLD or aarch64-elf	2021-01-12 20:18:24 +01:00