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Message-Id: <1499898783-25732-6-git-send-email-mark.rutland@arm.com>
Date: Wed, 12 Jul 2017 23:33:02 +0100
From: Mark Rutland <mark.rutland@....com>
To: ard.biesheuvel@...aro.org,
kernel-hardening@...ts.openwall.com,
linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org
Cc: akashi.takahiro@...aro.org,
catalin.marinas@....com,
dave.martin@....com,
james.morse@....com,
labbott@...oraproject.org,
will.deacon@....com,
keescook@...omium.org,
Mark Rutland <mark.rutland@....com>
Subject: [RFC PATCH 5/6] arm64: keep track of current stack
To reliably check stack bounds, we'll need to know whether we're on a
task stack, or an IRQ stack.
Stash the base of the current stack in thread_info so that we have this
information.
Signed-off-by: Mark Rutland <mark.rutland@....com>
---
arch/arm64/include/asm/thread_info.h | 3 +++
arch/arm64/kernel/asm-offsets.c | 3 +++
arch/arm64/kernel/entry.S | 7 +++++++
arch/arm64/kernel/head.S | 6 ++++++
arch/arm64/kernel/process.c | 4 ++++
5 files changed, 23 insertions(+)
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 3684f86..ae4f44b 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -62,6 +62,9 @@ struct thread_info {
#endif
unsigned long pcp_offset;
int preempt_count; /* 0 => preemptable, <0 => bug */
+#ifdef CONFIG_VMAP_STACK
+ unsigned long current_stack;
+#endif
};
#define INIT_THREAD_INFO(tsk) \
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 17001be..10c8ffa 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -40,6 +40,9 @@ int main(void)
DEFINE(TSK_TI_PREEMPT, offsetof(struct task_struct, thread_info.preempt_count));
DEFINE(TSK_TI_PCP, offsetof(struct task_struct, thread_info.pcp_offset));
DEFINE(TSK_TI_ADDR_LIMIT, offsetof(struct task_struct, thread_info.addr_limit));
+#ifdef CONFIG_VMAP_STACK
+ DEFINE(TSK_TI_CUR_STK, offsetof(struct task_struct, thread_info.current_stack));
+#endif
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
DEFINE(TSK_TI_TTBR0, offsetof(struct task_struct, thread_info.ttbr0));
#endif
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 773b3fea..7c8b164 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -258,6 +258,9 @@ alternative_else_nop_endif
/* switch to the irq stack */
mov sp, x26
+#ifdef CONFIG_VMAP_STACK
+ str x25, [tsk, #TSK_TI_CUR_STK]
+#endif
/*
* Add a dummy stack frame, this non-standard format is fixed up
@@ -275,6 +278,10 @@ alternative_else_nop_endif
*/
.macro irq_stack_exit
mov sp, x19
+#ifdef CONFIG_VMAP_STACK
+ and x19, x19, #~(THREAD_SIZE - 1)
+ str x19, [tsk, #TSK_TI_CUR_STK]
+#endif
.endm
/*
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index db77cac..3363846 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -325,6 +325,9 @@ __primary_switched:
add sp, x4, #THREAD_SIZE
adr_l x5, init_task
msr tpidr_el1, x5 // Save thread_info
+#ifdef CONFIG_VMAP_STACK
+ str x4, [x5, #TSK_TI_CUR_STK]
+#endif
adr_l x8, vectors // load VBAR_EL1 with virtual
msr vbar_el1, x8 // vector table address
@@ -616,6 +619,9 @@ __secondary_switched:
mov x3, #THREAD_START_SP
add sp, x1, x3
ldr x2, [x0, #CPU_BOOT_TASK]
+#ifdef CONFIG_VMAP_STACK
+ str x1, [x2, #TSK_TI_CUR_STK]
+#endif
msr tpidr_el1, x2
mov x29, #0
b secondary_start_kernel
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 4212da3..5dc5797 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -294,6 +294,10 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
ptrace_hw_copy_thread(p);
+#ifdef CONFIG_VMAP_STACK
+ p->thread_info.current_stack = (unsigned long)p->stack;
+#endif
+
return 0;
}
--
1.9.1
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