kfence: use pt_regs to generate stack trace on faults

[linux-2.6-microblaze.git] / mm / kfence / report.c

diff --git a/mm/kfence/report.c b/mm/kfence/report.c
index 64f27c8..4dbfa9a 100644 (file)
--- a/mm/kfence/report.c
+++ b/mm/kfence/report.c
@@ -10,6 +10,7 @@
 #include <linux/kernel.h>
 #include <linux/lockdep.h>
 #include <linux/printk.h>
+#include <linux/sched/debug.h>
 #include <linux/seq_file.h>
 #include <linux/stacktrace.h>
 #include <linux/string.h>
@@ -41,7 +42,6 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries
 {
        char buf[64];
        int skipnr, fallback = 0;
-       bool is_access_fault = false;
 
        if (type) {
                /* Depending on error type, find different stack entries. */
@@ -49,8 +49,12 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries
                case KFENCE_ERROR_UAF:
                case KFENCE_ERROR_OOB:
                case KFENCE_ERROR_INVALID:
-                       is_access_fault = true;
-                       break;
+                       /*
+                        * kfence_handle_page_fault() may be called with pt_regs
+                        * set to NULL; in that case we'll simply show the full
+                        * stack trace.
+                        */
+                       return 0;
                case KFENCE_ERROR_CORRUPTION:
                case KFENCE_ERROR_INVALID_FREE:
                        break;
@@ -60,26 +64,21 @@ static int get_stack_skipnr(const unsigned long stack_entries[], int num_entries
        for (skipnr = 0; skipnr < num_entries; skipnr++) {
                int len = scnprintf(buf, sizeof(buf), "%ps", (void *)stack_entries[skipnr]);
 
-               if (is_access_fault) {
-                       if (!strncmp(buf, KFENCE_SKIP_ARCH_FAULT_HANDLER, len))
-                               goto found;
-               } else {
-                       if (str_has_prefix(buf, "kfence_") || str_has_prefix(buf, "__kfence_") ||
-                           !strncmp(buf, "__slab_free", len)) {
-                               /*
-                                * In case of tail calls from any of the below
-                                * to any of the above.
-                                */
-                               fallback = skipnr + 1;
-                       }
-
-                       /* Also the *_bulk() variants by only checking prefixes. */
-                       if (str_has_prefix(buf, "kfree") ||
-                           str_has_prefix(buf, "kmem_cache_free") ||
-                           str_has_prefix(buf, "__kmalloc") ||
-                           str_has_prefix(buf, "kmem_cache_alloc"))
-                               goto found;
+               if (str_has_prefix(buf, "kfence_") || str_has_prefix(buf, "__kfence_") ||
+                   !strncmp(buf, "__slab_free", len)) {
+                       /*
+                        * In case of tail calls from any of the below
+                        * to any of the above.
+                        */
+                       fallback = skipnr + 1;
                }
+
+               /* Also the *_bulk() variants by only checking prefixes. */
+               if (str_has_prefix(buf, "kfree") ||
+                   str_has_prefix(buf, "kmem_cache_free") ||
+                   str_has_prefix(buf, "__kmalloc") ||
+                   str_has_prefix(buf, "kmem_cache_alloc"))
+                       goto found;
        }
        if (fallback < num_entries)
                return fallback;
@@ -157,13 +156,20 @@ static void print_diff_canary(unsigned long address, size_t bytes_to_show,
        pr_cont(" ]");
 }
 
-void kfence_report_error(unsigned long address, const struct kfence_metadata *meta,
-                        enum kfence_error_type type)
+void kfence_report_error(unsigned long address, struct pt_regs *regs,
+                        const struct kfence_metadata *meta, enum kfence_error_type type)
 {
        unsigned long stack_entries[KFENCE_STACK_DEPTH] = { 0 };
-       int num_stack_entries = stack_trace_save(stack_entries, KFENCE_STACK_DEPTH, 1);
-       int skipnr = get_stack_skipnr(stack_entries, num_stack_entries, &type);
        const ptrdiff_t object_index = meta ? meta - kfence_metadata : -1;
+       int num_stack_entries;
+       int skipnr = 0;
+
+       if (regs) {
+               num_stack_entries = stack_trace_save_regs(regs, stack_entries, KFENCE_STACK_DEPTH, 0);
+       } else {
+               num_stack_entries = stack_trace_save(stack_entries, KFENCE_STACK_DEPTH, 1);
+               skipnr = get_stack_skipnr(stack_entries, num_stack_entries, &type);
+       }
 
        /* Require non-NULL meta, except if KFENCE_ERROR_INVALID. */
        if (WARN_ON(type != KFENCE_ERROR_INVALID && !meta))
@@ -227,7 +233,10 @@ void kfence_report_error(unsigned long address, const struct kfence_metadata *me
 
        /* Print report footer. */
        pr_err("\n");
-       dump_stack_print_info(KERN_ERR);
+       if (IS_ENABLED(CONFIG_DEBUG_KERNEL) && regs)
+               show_regs(regs);
+       else
+               dump_stack_print_info(KERN_ERR);
        pr_err("==================================================================\n");
 
        lockdep_on();