Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

Pull ARM updates from Russell King:
 "Updates for IRQ stacks and virtually mapped stack support, and ftrace:

   - Support for IRQ and vmap'ed stacks

     This covers all the work related to implementing IRQ stacks and
     vmap'ed stacks for all 32-bit ARM systems that are currently
     supported by the Linux kernel, including RiscPC and Footbridge. It
     has been submitted for review in four different waves:

      - IRQ stacks support for v7 SMP systems [0]

      - vmap'ed stacks support for v7 SMP systems[1]

      - extending support for both IRQ stacks and vmap'ed stacks for all
        remaining configurations, including v6/v7 SMP multiplatform
        kernels and uniprocessor configurations including v7-M [2]

      - fixes and updates in [3]

   - ftrace fixes and cleanups

     Make all flavors of ftrace available on all builds, regardless of
     ISA choice, unwinder choice or compiler [4]:

      - use ADD not POP where possible

      - fix a couple of Thumb2 related issues

      - enable HAVE_FUNCTION_GRAPH_FP_TEST for robustness

      - enable the graph tracer with the EABI unwinder

      - avoid clobbering frame pointer registers to make Clang happy

   - Fixes for the above"

[0] https://lore.kernel.org/linux-arm-kernel/20211115084732.3704393-1-ardb@kernel.org/
[1] https://lore.kernel.org/linux-arm-kernel/20211122092816.2865873-1-ardb@kernel.org/
[2] https://lore.kernel.org/linux-arm-kernel/20211206164659.1495084-1-ardb@kernel.org/
[3] https://lore.kernel.org/linux-arm-kernel/20220124174744.1054712-1-ardb@kernel.org/
[4] https://lore.kernel.org/linux-arm-kernel/20220203082204.1176734-1-ardb@kernel.org/

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (62 commits)
  ARM: fix building NOMMU ARMv4/v5 kernels
  ARM: unwind: only permit stack switch when unwinding call_with_stack()
  ARM: Revert "unwind: dump exception stack from calling frame"
  ARM: entry: fix unwinder problems caused by IRQ stacks
  ARM: unwind: set frame.pc correctly for current-thread unwinding
  ARM: 9184/1: return_address: disable again for CONFIG_ARM_UNWIND=y
  ARM: 9183/1: unwind: avoid spurious warnings on bogus code addresses
  Revert "ARM: 9144/1: forbid ftrace with clang and thumb2_kernel"
  ARM: mach-bcm: disable ftrace in SMC invocation routines
  ARM: cacheflush: avoid clobbering the frame pointer
  ARM: kprobes: treat R7 as the frame pointer register in Thumb2 builds
  ARM: ftrace: enable the graph tracer with the EABI unwinder
  ARM: unwind: track location of LR value in stack frame
  ARM: ftrace: enable HAVE_FUNCTION_GRAPH_FP_TEST
  ARM: ftrace: avoid unnecessary literal loads
  ARM: ftrace: avoid redundant loads or clobbering IP
  ARM: ftrace: use trampolines to keep .init.text in branching range
  ARM: ftrace: use ADD not POP to counter PUSH at entry
  ARM: ftrace: ensure that ADR takes the Thumb bit into account
  ARM: make get_current() and __my_cpu_offset() __always_inline
  ...

1 files changed, 87 insertions, 6 deletions

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index cae4a748811f..b532039286a2 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -36,6 +36,7 @@
 #include <asm/ptrace.h>
 #include <asm/unwind.h>
 #include <asm/tls.h>
+#include <asm/stacktrace.h>
 #include <asm/system_misc.h>
 #include <asm/opcodes.h>
 
@@ -61,13 +62,24 @@ static int __init user_debug_setup(char *str)
 __setup("user_debug=", user_debug_setup);
 #endif
 
-static void dump_mem(const char *, const char *, unsigned long, unsigned long);
-
 void dump_backtrace_entry(unsigned long where, unsigned long from,
 			  unsigned long frame, const char *loglvl)
 {
 	unsigned long end = frame + 4 + sizeof(struct pt_regs);
 
+	if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER) &&
+	    IS_ENABLED(CONFIG_CC_IS_GCC) &&
+	    end > ALIGN(frame, THREAD_SIZE)) {
+		/*
+		 * If we are walking past the end of the stack, it may be due
+		 * to the fact that we are on an IRQ or overflow stack. In this
+		 * case, we can load the address of the other stack from the
+		 * frame record.
+		 */
+		frame = ((unsigned long *)frame)[-2] - 4;
+		end = frame + 4 + sizeof(struct pt_regs);
+	}
+
 #ifndef CONFIG_KALLSYMS
 	printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
 		loglvl, where, from);
@@ -111,7 +123,8 @@ void dump_backtrace_stm(u32 *stack, u32 instruction, const char *loglvl)
 static int verify_stack(unsigned long sp)
 {
 	if (sp < PAGE_OFFSET ||
-	    (sp > (unsigned long)high_memory && high_memory != NULL))
+	    (!IS_ENABLED(CONFIG_VMAP_STACK) &&
+	     sp > (unsigned long)high_memory && high_memory != NULL))
 		return -EFAULT;
 
 	return 0;
@@ -121,8 +134,8 @@ static int verify_stack(unsigned long sp)
 /*
  * Dump out the contents of some memory nicely...
  */
-static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
-		     unsigned long top)
+void dump_mem(const char *lvl, const char *str, unsigned long bottom,
+	      unsigned long top)
 {
 	unsigned long first;
 	int i;
@@ -281,7 +294,8 @@ static int __die(const char *str, int err, struct pt_regs *regs)
 
 	if (!user_mode(regs) || in_interrupt()) {
 		dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
-			 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
+			 ALIGN(regs->ARM_sp - THREAD_SIZE, THREAD_ALIGN)
+			 + THREAD_SIZE);
 		dump_backtrace(regs, tsk, KERN_EMERG);
 		dump_instr(KERN_EMERG, regs);
 	}
@@ -880,3 +894,70 @@ void __init early_trap_init(void *vectors_base)
 	 */
 }
 #endif
+
+#ifdef CONFIG_VMAP_STACK
+
+DECLARE_PER_CPU(u8 *, irq_stack_ptr);
+
+asmlinkage DEFINE_PER_CPU(u8 *, overflow_stack_ptr);
+
+static int __init allocate_overflow_stacks(void)
+{
+	u8 *stack;
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		stack = (u8 *)__get_free_page(GFP_KERNEL);
+		if (WARN_ON(!stack))
+			return -ENOMEM;
+		per_cpu(overflow_stack_ptr, cpu) = &stack[OVERFLOW_STACK_SIZE];
+	}
+	return 0;
+}
+early_initcall(allocate_overflow_stacks);
+
+asmlinkage void handle_bad_stack(struct pt_regs *regs)
+{
+	unsigned long tsk_stk = (unsigned long)current->stack;
+#ifdef CONFIG_IRQSTACKS
+	unsigned long irq_stk = (unsigned long)this_cpu_read(irq_stack_ptr);
+#endif
+	unsigned long ovf_stk = (unsigned long)this_cpu_read(overflow_stack_ptr);
+
+	console_verbose();
+	pr_emerg("Insufficient stack space to handle exception!");
+
+	pr_emerg("Task stack:     [0x%08lx..0x%08lx]\n",
+		 tsk_stk, tsk_stk + THREAD_SIZE);
+#ifdef CONFIG_IRQSTACKS
+	pr_emerg("IRQ stack:      [0x%08lx..0x%08lx]\n",
+		 irq_stk - THREAD_SIZE, irq_stk);
+#endif
+	pr_emerg("Overflow stack: [0x%08lx..0x%08lx]\n",
+		 ovf_stk - OVERFLOW_STACK_SIZE, ovf_stk);
+
+	die("kernel stack overflow", regs, 0);
+}
+
+#ifndef CONFIG_ARM_LPAE
+/*
+ * Normally, we rely on the logic in do_translation_fault() to update stale PMD
+ * entries covering the vmalloc space in a task's page tables when it first
+ * accesses the region in question. Unfortunately, this is not sufficient when
+ * the task stack resides in the vmalloc region, as do_translation_fault() is a
+ * C function that needs a stack to run.
+ *
+ * So we need to ensure that these PMD entries are up to date *before* the MM
+ * switch. As we already have some logic in the MM switch path that takes care
+ * of this, let's trigger it by bumping the counter every time the core vmalloc
+ * code modifies a PMD entry in the vmalloc region. Use release semantics on
+ * the store so that other CPUs observing the counter's new value are
+ * guaranteed to see the updated page table entries as well.
+ */
+void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
+{
+	if (start < VMALLOC_END && end > VMALLOC_START)
+		atomic_inc_return_release(&init_mm.context.vmalloc_seq);
+}
+#endif
+#endif