[PATCH v11 1/9] arm64: Add HAVE_REGS_AND_STACK_ACCESS_API feature
From: james.morse@arm.com (James Morse)
Date: 2016-03-11 18:08:45
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Hi David, On 09/03/16 05:32, David Long wrote:
From: "David A. Long" <redacted> Add HAVE_REGS_AND_STACK_ACCESS_API feature for arm64. Signed-off-by: David A. Long <redacted>
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index ff7f132..efebf0f 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c
[ ... SNIP ... ]
+/**
+ * regs_within_kernel_stack() - check the address in the stack
+ * @regs: pt_regs which contains kernel stack pointer.
+ * @addr: address which is checked.
+ *
+ * regs_within_kernel_stack() checks @addr is within the kernel stack page(s).
+ * If @addr is within the kernel stack, it returns true. If not, returns false.
+ */
+bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
+{
+ return ((addr & ~(THREAD_SIZE - 1)) ==
+ (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1)));I'm not sure where this is called from, but if kernel_stack_pointer(regs) could ever point into an irq_stack you will get the wrong result. arch/arm64/include/asm/irq.h has 'on_irq_stack(sp, cpu)' which should help, although you will need to check the bounds of the irq_stack separately. The horrible details...
From arch/arm64/kernel/irq.c:20 /* irq stack only needs to be 16 byte aligned - not IRQ_STACK_SIZE aligned. */ DEFINE_PER_CPU(unsigned long [IRQ_STACK_SIZE/sizeof(long)], irq_stack) __aligned(16);
This was because per-cpu variables can be at-most page aligned.
6cdf9c7ca687 ("arm64: Store struct thread_info in sp_el0") changed
current_thread_info() to work on these weirdly aligned irq_stacks.
Thanks,
James