linux-kernel - [GIT pull] x86/urgent for v5.7-rc7

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Message-ID: <159033288358.21635.2357843074773527660.tglx@nanos.tec.linutronix.de>
Date:   Sun, 24 May 2020 15:08:03 -0000
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [GIT pull] x86/urgent for v5.7-rc7

Linus,

please pull the latest x86/urgent branch from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-urgent-2020-05-24

up to:  187b96db5ca7: x86/unwind/orc: Fix unwind_get_return_address_ptr() for inactive tasks


Two fixes for x86:

  - Unbreak stack dumps for inactive tasks by interpreting the special
    first frame left by __switch_to_asm() correctly. The recent change not
    to skip the first frame so ORC and frame unwinder behave in the same
    way caused all entries to be unreliable, i.e. prepended with '?'.

  - Use cpumask_available() instead of an implicit NULL check of a
    cpumask_var_t in mmio trace to prevent a Clang build warning

Thanks,

	tglx

------------------>
Josh Poimboeuf (1):
      x86/unwind/orc: Fix unwind_get_return_address_ptr() for inactive tasks

Nathan Chancellor (1):
      x86/mmiotrace: Use cpumask_available() for cpumask_var_t variables


 arch/x86/kernel/unwind_orc.c | 7 +++++++
 arch/x86/mm/mmio-mod.c       | 4 ++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index fa79e4227d3d..7f969b2d240f 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -320,12 +320,19 @@ EXPORT_SYMBOL_GPL(unwind_get_return_address);
 
 unsigned long *unwind_get_return_address_ptr(struct unwind_state *state)
 {
+	struct task_struct *task = state->task;
+
 	if (unwind_done(state))
 		return NULL;
 
 	if (state->regs)
 		return &state->regs->ip;
 
+	if (task != current && state->sp == task->thread.sp) {
+		struct inactive_task_frame *frame = (void *)task->thread.sp;
+		return &frame->ret_addr;
+	}
+
 	if (state->sp)
 		return (unsigned long *)state->sp - 1;
 
diff --git a/arch/x86/mm/mmio-mod.c b/arch/x86/mm/mmio-mod.c
index 109325d77b3e..43fd19b3f118 100644
--- a/arch/x86/mm/mmio-mod.c
+++ b/arch/x86/mm/mmio-mod.c
@@ -372,7 +372,7 @@ static void enter_uniprocessor(void)
 	int cpu;
 	int err;
 
-	if (downed_cpus == NULL &&
+	if (!cpumask_available(downed_cpus) &&
 	    !alloc_cpumask_var(&downed_cpus, GFP_KERNEL)) {
 		pr_notice("Failed to allocate mask\n");
 		goto out;
@@ -402,7 +402,7 @@ static void leave_uniprocessor(void)
 	int cpu;
 	int err;
 
-	if (downed_cpus == NULL || cpumask_weight(downed_cpus) == 0)
+	if (!cpumask_available(downed_cpus) || cpumask_weight(downed_cpus) == 0)
 		return;
 	pr_notice("Re-enabling CPUs...\n");
 	for_each_cpu(cpu, downed_cpus) {