When debugging eh_frame issues, the error messages aren't all that helpful without knowing what file a corresponding .eh_frame[_hdr] section belongs to. Prefix debug output strings with the file name.
Based on Josh Poimboeuf's, Steven Rostedt's, and my unwind user sframe implementation. Signed-off-by: Jens Remus <[email protected]> --- include/linux/eh_frame.h | 4 ++++ kernel/unwind/eh_frame.c | 13 ++++++++---- kernel/unwind/eh_frame_debug.h | 37 ++++++++++++++++++++++++++++++++++ 3 files changed, 50 insertions(+), 4 deletions(-) diff --git a/include/linux/eh_frame.h b/include/linux/eh_frame.h index 740316b19df3..70b4f9d12828 100644 --- a/include/linux/eh_frame.h +++ b/include/linux/eh_frame.h @@ -11,6 +11,10 @@ struct eh_frame_section { struct rcu_head rcu; +#ifdef CONFIG_DYNAMIC_DEBUG + const char *filename; +#endif + unsigned long eh_frame_hdr_start; unsigned long eh_frame_hdr_end; unsigned long text_start; diff --git a/kernel/unwind/eh_frame.c b/kernel/unwind/eh_frame.c index 327849ea4a69..96237a96d263 100644 --- a/kernel/unwind/eh_frame.c +++ b/kernel/unwind/eh_frame.c @@ -1207,15 +1207,18 @@ int eh_frame_find(unsigned long ip, struct unwind_user_frame *frame) * e.g. EINVAL (corrupted) or EFAULT (inaccessible). * Keep if ENOENT (not found) or EOPNOTSUPP (unsupported CFI). */ - if (ret && (ret != -ENOENT && ret != -EOPNOTSUPP)) + if (ret && (ret != -ENOENT && ret != -EOPNOTSUPP)) { + dbg_sec("removing bad .eh_frame[_hdr] section\n"); if (eh_frame_remove_section(sec->eh_frame_hdr_start)) dbg("eh_frame_remove_section() failed\n"); + } return ret; } static void free_section(struct eh_frame_section *sec) { + dbg_free(sec); kfree(sec); } @@ -1342,6 +1345,8 @@ int eh_frame_add_section(unsigned long eh_frame_hdr_start, sec->text_start = text_start; sec->text_end = text_end; + dbg_init(sec); + ret = eh_frame_read_header(sec); if (ret) goto err_free; @@ -1349,8 +1354,8 @@ int eh_frame_add_section(unsigned long eh_frame_hdr_start, ret = mtree_insert_range(eh_frame_mt, sec->text_start, sec->text_end - 1, sec, GFP_KERNEL_ACCOUNT); if (ret) { - dbg("mtree_insert_range failed: text=%lx-%lx\n", - sec->text_start, sec->text_end); + dbg_sec("mtree_insert_range failed: text=%lx-%lx\n", + sec->text_start, sec->text_end); goto err_free; } @@ -1372,7 +1377,7 @@ static int __eh_frame_remove_section(struct ma_state *mas, struct eh_frame_section *sec) { if (mas_erase(mas) != sec) { - dbg("mas_erase failed: text=%lx\n", sec->text_start); + dbg_sec("mas_erase failed: text=%lx\n", sec->text_start); return -EINVAL; } diff --git a/kernel/unwind/eh_frame_debug.h b/kernel/unwind/eh_frame_debug.h index 5a3e4e7f065a..40a80861d4d4 100644 --- a/kernel/unwind/eh_frame_debug.h +++ b/kernel/unwind/eh_frame_debug.h @@ -3,6 +3,7 @@ #define _EH_FRAME_DEBUG_H #include <linux/eh_frame.h> +#include <linux/mm.h> #include "eh_frame.h" #ifdef CONFIG_DYNAMIC_DEBUG @@ -10,9 +11,45 @@ #define dbg(fmt, ...) \ pr_debug("%s (%d): " fmt, current->comm, current->pid, ##__VA_ARGS__) +#define dbg_sec(fmt, ...) \ + dbg("%s: " fmt, sec->filename, ##__VA_ARGS__) + +static inline void dbg_init(struct eh_frame_section *sec) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + const char *name; + + guard(mmap_read_lock)(mm); + vma = vma_lookup(mm, sec->eh_frame_hdr_start); + if (!vma) + sec->filename = kstrdup("(vma gone???)", GFP_KERNEL_ACCOUNT); + else if (vma_is_anonymous(vma)) + sec->filename = kstrdup("(anonymous)", GFP_KERNEL_ACCOUNT); + else if (vma->vm_file) + sec->filename = kstrdup_quotable_file(vma->vm_file, GFP_KERNEL_ACCOUNT); + else if (vma->vm_ops && vma->vm_ops->name && (name = vma->vm_ops->name(vma))) + sec->filename = kstrdup(name, GFP_KERNEL_ACCOUNT); + else if (arch_vma_name(vma)) + sec->filename = kstrdup(arch_vma_name(vma), GFP_KERNEL_ACCOUNT); + else if (!vma->vm_mm) + sec->filename = kstrdup("(vdso)", GFP_KERNEL_ACCOUNT); + else + sec->filename = kstrdup("(vma unknown???)", GFP_KERNEL_ACCOUNT); +} + +static inline void dbg_free(struct eh_frame_section *sec) +{ + kfree(sec->filename); +} + #else /* !CONFIG_DYNAMIC_DEBUG */ #define dbg(args...) no_printk(args) +#define dbg_sec(args...) no_printk(args) + +static inline void dbg_init(struct eh_frame_section *sec) {} +static inline void dbg_free(struct eh_frame_section *sec) {} #endif /* !CONFIG_DYNAMIC_DEBUG */ -- 2.53.0
