[to-be-updated] arm64-implement-stack_trace_save_shadow.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: arm64: implement stack_trace_save_shadow
has been removed from the -mm tree.  Its filename was
     arm64-implement-stack_trace_save_shadow.patch

This patch was dropped because an updated version will be merged

------------------------------------------------------
From: Andrey Konovalov <andreyknvl@google.com>
Subject: arm64: implement stack_trace_save_shadow

Implement the stack_trace_save_shadow() interface that collects stack
traces based on the Shadow Call Stack (SCS) for arm64.

The implementation walks through available SCS pointers (the per-task one
and the per-interrupt-type ones) and copies the frames.

Note that the frame of the interrupted function is not included into the
stack trace, as it is not yet saved on the SCS when an interrupt happens.

[akpm@linux-foundation.org: add ifdefs to arch/arm64/kernel/stacktrace.c]
Link: https://lkml.kernel.org/r/0bb72ea8fa88ef9ae3508c23d993952a0ae6f0f9.1648049113.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Florian Mayer <fmayer@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/arm64/Kconfig             |    1 
 arch/arm64/kernel/stacktrace.c |   85 +++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)

--- a/arch/arm64/Kconfig~arm64-implement-stack_trace_save_shadow
+++ a/arch/arm64/Kconfig
@@ -200,6 +200,7 @@ config ARM64
 	select HAVE_FUNCTION_ARG_ACCESS_API
 	select MMU_GATHER_RCU_TABLE_FREE
 	select HAVE_RSEQ
+	select HAVE_SHADOW_STACKTRACE
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES
--- a/arch/arm64/kernel/stacktrace.c~arm64-implement-stack_trace_save_shadow
+++ a/arch/arm64/kernel/stacktrace.c
@@ -12,9 +12,11 @@
 #include <linux/sched/debug.h>
 #include <linux/sched/task_stack.h>
 #include <linux/stacktrace.h>
+#include <linux/scs.h>
 
 #include <asm/irq.h>
 #include <asm/pointer_auth.h>
+#include <asm/scs.h>
 #include <asm/stack_pointer.h>
 #include <asm/stacktrace.h>
 
@@ -210,3 +212,86 @@ noinline notrace void arch_stack_walk(st
 
 	walk_stackframe(task, &frame, consume_entry, cookie);
 }
+
+#ifdef CONFIG_SHADOW_CALL_STACK
+static const struct {
+	unsigned long ** __percpu saved;
+	unsigned long ** __percpu base;
+} scs_parts[] = {
+#ifdef CONFIG_ARM_SDE_INTERFACE
+	{
+		.saved = &sdei_shadow_call_stack_critical_saved_ptr,
+		.base = &sdei_shadow_call_stack_critical_ptr,
+	},
+	{
+		.saved = &sdei_shadow_call_stack_normal_saved_ptr,
+		.base = &sdei_shadow_call_stack_normal_ptr,
+	},
+#endif /* CONFIG_ARM_SDE_INTERFACE */
+	{
+		.saved = &irq_shadow_call_stack_saved_ptr,
+		.base = &irq_shadow_call_stack_ptr,
+	},
+};
+
+static inline bool walk_shadow_stack_part(
+				unsigned long *scs_top, unsigned long *scs_base,
+				unsigned long *store, unsigned int size,
+				unsigned int *skipnr, unsigned int *len)
+{
+	unsigned long *frame;
+
+	for (frame = scs_top; frame >= scs_base; frame--) {
+		if (*skipnr > 0) {
+			(*skipnr)--;
+			continue;
+		}
+		/*
+		 * Do not leak PTR_AUTH tags in stack traces.
+		 * Use READ_ONCE_NOCHECK as SCS is poisoned with Generic KASAN.
+		 */
+		store[(*len)++] =
+			ptrauth_strip_insn_pac(READ_ONCE_NOCHECK(*frame));
+		if (*len >= size)
+			return true;
+	}
+
+	return false;
+}
+
+noinline notrace int arch_stack_walk_shadow(unsigned long *store,
+					    unsigned int size,
+					    unsigned int skipnr)
+{
+	unsigned long *scs_top, *scs_base, *scs_next;
+	unsigned int len = 0, part;
+
+	preempt_disable();
+
+	/* Get the SCS pointer. */
+	asm volatile("mov %0, x18" : "=&r" (scs_top));
+
+	/* The top SCS slot is empty. */
+	scs_top -= 1;
+
+	/* Handle SDEI and hardirq frames. */
+	for (part = 0; part < ARRAY_SIZE(scs_parts); part++) {
+		scs_next = *this_cpu_ptr(scs_parts[part].saved);
+		if (scs_next) {
+			scs_base = *this_cpu_ptr(scs_parts[part].base);
+			if (walk_shadow_stack_part(scs_top, scs_base, store,
+						   size, &skipnr, &len))
+				goto out;
+			scs_top = scs_next;
+		}
+	}
+
+	/* Handle task and softirq frames. */
+	scs_base = task_scs(current);
+	walk_shadow_stack_part(scs_top, scs_base, store, size, &skipnr, &len);
+
+out:
+	preempt_enable();
+	return len;
+}
+#endif		/* CONFIG_SHADOW_CALL_STACK */
_

Patches currently in -mm which might be from andreyknvl@google.com are

mm-kasan-fix-__gfp_bits_shift-definition-breaking-lockdep.patch
kasan-use-stack_trace_save_shadow.patch