linux-kernel - [PATCH v3 1/3] arm64, scs: expose irq_shadow_call_stack

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Date:   Wed, 13 Apr 2022 21:26:44 +0200
From:   andrey.konovalov@...ux.dev
To:     Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Mark Rutland <mark.rutland@....com>
Cc:     Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev@...glegroups.com,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        linux-arm-kernel@...ts.infradead.org,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Florian Mayer <fmayer@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH v3 1/3] arm64, scs: expose irq_shadow_call_stack_ptr

From: Andrey Konovalov <andreyknvl@...gle.com>

When a hardirq happens, the Shadow Call Stack (SCS) pointer is switched
to a per-hardirq one, which is stored in irq_shadow_call_stack_ptr per-CPU.

Collecting stack traces based on SCS in hardirqs requires access to
irq_shadow_call_stack_ptr.

Expose irq_shadow_call_stack_ptr in arch/arm64/include/asm/scs.h.

For symmetry, move sdei_shadow_call_stack_normal_ptr and
sdei_shadow_call_stack_critical_ptr declarations there too.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 arch/arm64/include/asm/scs.h | 10 +++++++++-
 arch/arm64/kernel/irq.c      |  4 +---
 arch/arm64/kernel/sdei.c     |  3 ---
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/scs.h b/arch/arm64/include/asm/scs.h
index 8297bccf0784..9d9ac04014f1 100644
--- a/arch/arm64/include/asm/scs.h
+++ b/arch/arm64/include/asm/scs.h
@@ -24,6 +24,14 @@
 	.endm
 #endif /* CONFIG_SHADOW_CALL_STACK */
 
-#endif /* __ASSEMBLY __ */
+#else /* __ASSEMBLY__ */
+
+#include <linux/percpu.h>
+
+DECLARE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr);
+DECLARE_PER_CPU(unsigned long *, sdei_shadow_call_stack_normal_ptr);
+DECLARE_PER_CPU(unsigned long *, sdei_shadow_call_stack_critical_ptr);
+
+#endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_SCS_H */
diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
index bda49430c9ea..9d85c82f0b1c 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -21,6 +21,7 @@
 #include <linux/seq_file.h>
 #include <linux/vmalloc.h>
 #include <asm/daifflags.h>
+#include <asm/scs.h>
 #include <asm/vmap_stack.h>
 
 /* Only access this in an NMI enter/exit */
@@ -28,9 +29,6 @@ DEFINE_PER_CPU(struct nmi_ctx, nmi_contexts);
 
 DEFINE_PER_CPU(unsigned long *, irq_stack_ptr);
 
-
-DECLARE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr);
-
 #ifdef CONFIG_SHADOW_CALL_STACK
 DEFINE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr);
 #endif
diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c
index d20620a1c51a..882f88ce8d4d 100644
--- a/arch/arm64/kernel/sdei.c
+++ b/arch/arm64/kernel/sdei.c
@@ -39,9 +39,6 @@ DEFINE_PER_CPU(unsigned long *, sdei_stack_normal_ptr);
 DEFINE_PER_CPU(unsigned long *, sdei_stack_critical_ptr);
 #endif
 
-DECLARE_PER_CPU(unsigned long *, sdei_shadow_call_stack_normal_ptr);
-DECLARE_PER_CPU(unsigned long *, sdei_shadow_call_stack_critical_ptr);
-
 #ifdef CONFIG_SHADOW_CALL_STACK
 DEFINE_PER_CPU(unsigned long *, sdei_shadow_call_stack_normal_ptr);
 DEFINE_PER_CPU(unsigned long *, sdei_shadow_call_stack_critical_ptr);
-- 
2.25.1