arch: Make ARCH_STACKWALK independent of STACKTRACE

Make arch_stack_walk() available for ARCH_STACKWALK architectures
without it being entangled in STACKTRACE.

Link: https://lore.kernel.org/lkml/20211022152104.356586621@infradead.org/
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[Mark: rebase, drop unnecessary arm change]
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/20211129142849.3056714-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/stacktrace.c

@@ -221,8 +221,6 @@ void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
 	barrier();
 }
 
-#ifdef CONFIG_STACKTRACE
-
 noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
 			      void *cookie, struct task_struct *task,
 			      struct pt_regs *regs)
@@ -241,5 +239,3 @@ noinline notrace void arch_stack_walk(stack_trace_consume_fn consume_entry,
 
 	walk_stackframe(task, &frame, consume_entry, cookie);
 }
-
-#endif

arch/powerpc/kernel/Makefile

@@ -47,7 +47,7 @@ obj-y				:= cputable.o syscalls.o \
 				   udbg.o misc.o io.o misc_$(BITS).o \
 				   of_platform.o prom_parse.o firmware.o \
 				   hw_breakpoint_constraints.o interrupt.o \
-				   kdebugfs.o
+				   kdebugfs.o stacktrace.o
 obj-y				+= ptrace/
 obj-$(CONFIG_PPC64)		+= setup_64.o \
 				   paca.o nvram_64.o note.o
@@ -116,7 +116,6 @@ obj-$(CONFIG_OPTPROBES)		+= optprobes.o optprobes_head.o
 obj-$(CONFIG_KPROBES_ON_FTRACE)	+= kprobes-ftrace.o
 obj-$(CONFIG_UPROBES)		+= uprobes.o
 obj-$(CONFIG_PPC_UDBG_16550)	+= legacy_serial.o udbg_16550.o
-obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_SWIOTLB)		+= dma-swiotlb.o
 obj-$(CONFIG_ARCH_HAS_DMA_SET_MASK) += dma-mask.o
 

arch/riscv/kernel/stacktrace.c

@@ -139,12 +139,8 @@ unsigned long __get_wchan(struct task_struct *task)
 	return pc;
 }
 
-#ifdef CONFIG_STACKTRACE
-
 noinline void arch_stack_walk(stack_trace_consume_fn consume_entry, void *cookie,
 		     struct task_struct *task, struct pt_regs *regs)
 {
 	walk_stackframe(task, regs, consume_entry, cookie);
 }
-
-#endif /* CONFIG_STACKTRACE */

arch/s390/kernel/Makefile

@@ -40,7 +40,7 @@ obj-y	+= sysinfo.o lgr.o os_info.o machine_kexec.o
 obj-y	+= runtime_instr.o cache.o fpu.o dumpstack.o guarded_storage.o sthyi.o
 obj-y	+= entry.o reipl.o relocate_kernel.o kdebugfs.o alternative.o
 obj-y	+= nospec-branch.o ipl_vmparm.o machine_kexec_reloc.o unwind_bc.o
-obj-y	+= smp.o text_amode31.o
+obj-y	+= smp.o text_amode31.o stacktrace.o
 
 extra-y				+= head64.o vmlinux.lds
 
@@ -55,7 +55,6 @@ compat-obj-$(CONFIG_AUDIT)	+= compat_audit.o
 obj-$(CONFIG_COMPAT)		+= compat_linux.o compat_signal.o
 obj-$(CONFIG_COMPAT)		+= $(compat-obj-y)
 obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
-obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 obj-$(CONFIG_KPROBES)		+= kprobes.o
 obj-$(CONFIG_KPROBES)		+= kprobes_insn_page.o
 obj-$(CONFIG_FUNCTION_TRACER)	+= mcount.o ftrace.o

arch/x86/kernel/Makefile

@@ -84,7 +84,7 @@ obj-$(CONFIG_IA32_EMULATION)	+= tls.o
 obj-y				+= step.o
 obj-$(CONFIG_INTEL_TXT)		+= tboot.o
 obj-$(CONFIG_ISA_DMA_API)	+= i8237.o
-obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
+obj-y				+= stacktrace.o
 obj-y				+= cpu/
 obj-y				+= acpi/
 obj-y				+= reboot.o

include/linux/stacktrace.h

@@ -8,22 +8,6 @@
 struct task_struct;
 struct pt_regs;
 
-#ifdef CONFIG_STACKTRACE
-void stack_trace_print(const unsigned long *trace, unsigned int nr_entries,
-		       int spaces);
-int stack_trace_snprint(char *buf, size_t size, const unsigned long *entries,
-			unsigned int nr_entries, int spaces);
-unsigned int stack_trace_save(unsigned long *store, unsigned int size,
-			      unsigned int skipnr);
-unsigned int stack_trace_save_tsk(struct task_struct *task,
-				  unsigned long *store, unsigned int size,
-				  unsigned int skipnr);
-unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
-				   unsigned int size, unsigned int skipnr);
-unsigned int stack_trace_save_user(unsigned long *store, unsigned int size);
-unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries);
-
-/* Internal interfaces. Do not use in generic code */
 #ifdef CONFIG_ARCH_STACKWALK
 
 /**
@@ -76,8 +60,25 @@ int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, void *cookie,
 
 void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
 			  const struct pt_regs *regs);
+#endif /* CONFIG_ARCH_STACKWALK */
 
-#else /* CONFIG_ARCH_STACKWALK */
+#ifdef CONFIG_STACKTRACE
+void stack_trace_print(const unsigned long *trace, unsigned int nr_entries,
+		       int spaces);
+int stack_trace_snprint(char *buf, size_t size, const unsigned long *entries,
+			unsigned int nr_entries, int spaces);
+unsigned int stack_trace_save(unsigned long *store, unsigned int size,
+			      unsigned int skipnr);
+unsigned int stack_trace_save_tsk(struct task_struct *task,
+				  unsigned long *store, unsigned int size,
+				  unsigned int skipnr);
+unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
+				   unsigned int size, unsigned int skipnr);
+unsigned int stack_trace_save_user(unsigned long *store, unsigned int size);
+unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries);
+
+#ifndef CONFIG_ARCH_STACKWALK
+/* Internal interfaces. Do not use in generic code */
 struct stack_trace {
 	unsigned int nr_entries, max_entries;
 	unsigned long *entries;