RISC-V: fixups to work with crash tool

A handful of fixes to our kexec/crash kernel support that allow crash
tool to function.

Link: https://lore.kernel.org/r/mhng-f5fdaa37-e99a-4214-a297-ec81f0fed0c1@palmer-mbp2014

* commit 'f9293ad46d8ba9909187a37b7215324420ad4596':
  RISC-V: Add modules to virtual kernel memory layout dump
  RISC-V: Fixup schedule out issue in machine_crash_shutdown()
  RISC-V: Fixup get incorrect user mode PC for kernel mode regs
  RISC-V: kexec: Fixup use of smp_processor_id() in preemptible context

Author: palmer-dabbelt

arch/riscv/kernel/crash_save_regs.S

@@ -44,7 +44,7 @@ SYM_CODE_START(riscv_crash_save_regs)
 	REG_S t6,  PT_T6(a0)	/* x31 */
 
 	csrr t1, CSR_STATUS
-	csrr t2, CSR_EPC
+	auipc t2, 0x0
 	csrr t3, CSR_TVAL
 	csrr t4, CSR_CAUSE
 

arch/riscv/kernel/machine_kexec.c

@@ -138,19 +138,37 @@ void machine_shutdown(void)
 #endif
 }
 
+/* Override the weak function in kernel/panic.c */
+void crash_smp_send_stop(void)
+{
+	static int cpus_stopped;
+
+	/*
+	 * This function can be called twice in panic path, but obviously
+	 * we execute this only once.
+	 */
+	if (cpus_stopped)
+		return;
+
+	smp_send_stop();
+	cpus_stopped = 1;
+}
+
 /*
  * machine_crash_shutdown - Prepare to kexec after a kernel crash
  *
  * This function is called by crash_kexec just before machine_kexec
- * below and its goal is similar to machine_shutdown, but in case of
- * a kernel crash. Since we don't handle such cases yet, this function
- * is empty.
+ * and its goal is to shutdown non-crashing cpus and save registers.
  */
 void
 machine_crash_shutdown(struct pt_regs *regs)
 {
+	local_irq_disable();
+
+	/* shutdown non-crashing cpus */
+	crash_smp_send_stop();
+
 	crash_save_cpu(regs, smp_processor_id());
-	machine_shutdown();
 	pr_info("Starting crashdump kernel...\n");
 }
 
@@ -171,7 +189,7 @@ machine_kexec(struct kimage *image)
 	struct kimage_arch *internal = &image->arch;
 	unsigned long jump_addr = (unsigned long) image->start;
 	unsigned long first_ind_entry = (unsigned long) &image->head;
-	unsigned long this_cpu_id = smp_processor_id();
+	unsigned long this_cpu_id = __smp_processor_id();
 	unsigned long this_hart_id = cpuid_to_hartid_map(this_cpu_id);
 	unsigned long fdt_addr = internal->fdt_addr;
 	void *control_code_buffer = page_address(image->control_code_page);

arch/riscv/mm/init.c

@@ -135,6 +135,10 @@ static void __init print_vm_layout(void)
 		(unsigned long)VMEMMAP_END);
 	print_ml("vmalloc", (unsigned long)VMALLOC_START,
 		(unsigned long)VMALLOC_END);
+#ifdef CONFIG_64BIT
+	print_ml("modules", (unsigned long)MODULES_VADDR,
+		(unsigned long)MODULES_END);
+#endif
 	print_ml("lowmem", (unsigned long)PAGE_OFFSET,
 		(unsigned long)high_memory);
 	if (IS_ENABLED(CONFIG_64BIT)) {