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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) {
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