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Message-Id: <20201130233442.2562064-3-samitolvanen@google.com>
Date: Mon, 30 Nov 2020 15:34:42 -0800
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Will Deacon <will@...nel.org>,
Catalin Marinas <catalin.marinas@....com>
Cc: Mark Rutland <mark.rutland@....com>,
James Morse <james.morse@....com>,
Ard Biesheuvel <ard.biesheuvel@...aro.org>,
Kees Cook <keescook@...omium.org>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH v3 2/2] arm64: scs: use vmapped IRQ and SDEI shadow stacks
Use scs_alloc() to allocate also IRQ and SDEI shadow stacks instead of
using statically allocated stacks.
Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
Acked-by: Will Deacon <will@...nel.org>
---
arch/arm64/kernel/Makefile | 1 -
arch/arm64/kernel/entry.S | 6 ++--
arch/arm64/kernel/irq.c | 19 +++++++++++
arch/arm64/kernel/scs.c | 16 ---------
arch/arm64/kernel/sdei.c | 70 ++++++++++++++++++++++++++++++++++++++
include/linux/scs.h | 4 ---
6 files changed, 92 insertions(+), 24 deletions(-)
delete mode 100644 arch/arm64/kernel/scs.c
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index bbaf0bc4ad60..86364ab6f13f 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -58,7 +58,6 @@ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_CRASH_CORE) += crash_core.o
obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o
obj-$(CONFIG_ARM64_PTR_AUTH) += pointer_auth.o
-obj-$(CONFIG_SHADOW_CALL_STACK) += scs.o
obj-$(CONFIG_ARM64_MTE) += mte.o
obj-y += vdso/ probes/
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index b295fb912b12..5c2ac4b5b2da 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -441,7 +441,7 @@ SYM_CODE_END(__swpan_exit_el0)
#ifdef CONFIG_SHADOW_CALL_STACK
/* also switch to the irq shadow stack */
- adr_this_cpu scs_sp, irq_shadow_call_stack, x26
+ ldr_this_cpu scs_sp, irq_shadow_call_stack_ptr, x26
#endif
9998:
@@ -1097,9 +1097,9 @@ SYM_CODE_START(__sdei_asm_handler)
#ifdef CONFIG_SHADOW_CALL_STACK
/* Use a separate shadow call stack for normal and critical events */
cbnz w4, 3f
- adr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal, tmp=x6
+ ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal_ptr, tmp=x6
b 4f
-3: adr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical, tmp=x6
+3: ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical_ptr, tmp=x6
4:
#endif
diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
index 9cf2fb87584a..5b7ada9d9559 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -17,6 +17,7 @@
#include <linux/init.h>
#include <linux/irqchip.h>
#include <linux/kprobes.h>
+#include <linux/scs.h>
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
#include <asm/daifflags.h>
@@ -27,6 +28,22 @@ 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
+
+static void init_irq_scs(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ per_cpu(irq_shadow_call_stack_ptr, cpu) =
+ scs_alloc(cpu_to_node(cpu));
+}
+
#ifdef CONFIG_VMAP_STACK
static void init_irq_stacks(void)
{
@@ -54,6 +71,8 @@ static void init_irq_stacks(void)
void __init init_IRQ(void)
{
init_irq_stacks();
+ if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK))
+ init_irq_scs();
irqchip_init();
if (!handle_arch_irq)
panic("No interrupt controller found.");
diff --git a/arch/arm64/kernel/scs.c b/arch/arm64/kernel/scs.c
deleted file mode 100644
index e8f7ff45dd8f..000000000000
--- a/arch/arm64/kernel/scs.c
+++ /dev/null
@@ -1,16 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Shadow Call Stack support.
- *
- * Copyright (C) 2019 Google LLC
- */
-
-#include <linux/percpu.h>
-#include <linux/scs.h>
-
-DEFINE_SCS(irq_shadow_call_stack);
-
-#ifdef CONFIG_ARM_SDE_INTERFACE
-DEFINE_SCS(sdei_shadow_call_stack_normal);
-DEFINE_SCS(sdei_shadow_call_stack_critical);
-#endif
diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c
index 7689f2031c0c..d12fd786b267 100644
--- a/arch/arm64/kernel/sdei.c
+++ b/arch/arm64/kernel/sdei.c
@@ -7,6 +7,7 @@
#include <linux/hardirq.h>
#include <linux/irqflags.h>
#include <linux/sched/task_stack.h>
+#include <linux/scs.h>
#include <linux/uaccess.h>
#include <asm/alternative.h>
@@ -37,6 +38,14 @@ 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);
+#endif
+
static void _free_sdei_stack(unsigned long * __percpu *ptr, int cpu)
{
unsigned long *p;
@@ -90,6 +99,59 @@ static int init_sdei_stacks(void)
return err;
}
+static void _free_sdei_scs(unsigned long * __percpu *ptr, int cpu)
+{
+ void *s;
+
+ s = per_cpu(*ptr, cpu);
+ if (s) {
+ per_cpu(*ptr, cpu) = NULL;
+ scs_free(s);
+ }
+}
+
+static void free_sdei_scs(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ _free_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu);
+ _free_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu);
+ }
+}
+
+static int _init_sdei_scs(unsigned long * __percpu *ptr, int cpu)
+{
+ void *s;
+
+ s = scs_alloc(cpu_to_node(cpu));
+ if (!s)
+ return -ENOMEM;
+ per_cpu(*ptr, cpu) = s;
+
+ return 0;
+}
+
+static int init_sdei_scs(void)
+{
+ int cpu;
+ int err = 0;
+
+ for_each_possible_cpu(cpu) {
+ err = _init_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu);
+ if (err)
+ break;
+ err = _init_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu);
+ if (err)
+ break;
+ }
+
+ if (err)
+ free_sdei_scs();
+
+ return err;
+}
+
static bool on_sdei_normal_stack(unsigned long sp, struct stack_info *info)
{
unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr);
@@ -138,6 +200,14 @@ unsigned long sdei_arch_get_entry_point(int conduit)
return 0;
}
+ if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) {
+ if (init_sdei_scs()) {
+ if (IS_ENABLED(CONFIG_VMAP_STACK))
+ free_sdei_stacks();
+ return 0;
+ }
+ }
+
sdei_exit_mode = (conduit == SMCCC_CONDUIT_HVC) ? SDEI_EXIT_HVC : SDEI_EXIT_SMC;
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
diff --git a/include/linux/scs.h b/include/linux/scs.h
index 2a506c2a16f4..18122d9e17ff 100644
--- a/include/linux/scs.h
+++ b/include/linux/scs.h
@@ -22,10 +22,6 @@
/* An illegal pointer value to mark the end of the shadow stack. */
#define SCS_END_MAGIC (0x5f6UL + POISON_POINTER_DELTA)
-/* Allocate a static per-CPU shadow stack */
-#define DEFINE_SCS(name) \
- DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], name) \
-
#define task_scs(tsk) (task_thread_info(tsk)->scs_base)
#define task_scs_sp(tsk) (task_thread_info(tsk)->scs_sp)
--
2.29.2.454.gaff20da3a2-goog
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