For a previous version before making asked for corrections, this was: Reviewed-by: Kees Cook <[email protected]>
On Mon, 2018-10-01 at 14:38 -0700, Rick Edgecombe wrote: > Add debugfs file "modfraginfo" for providing info on module space > fragmentation. > This can be used for determining if loadable module randomization is causing > any > problems for extreme module loading situations, like huge numbers of modules > or > extremely large modules. > > Sample output when KASLR is enabled and X86_64 is configured: > Largest free space: 897912 kB > Total free space: 1025424 kB > Allocations in backup area: 0 > > Sample output when just X86_64: > Largest free space: 897912 kB > Total free space: 1025424 kB > > Signed-off-by: Rick Edgecombe <[email protected]> > --- > mm/vmalloc.c | 98 > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 97 insertions(+), 1 deletion(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 1954458..1b3c3da 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -18,6 +18,7 @@ > #include <linux/interrupt.h> > #include <linux/proc_fs.h> > #include <linux/seq_file.h> > +#include <linux/debugfs.h> > #include <linux/debugobjects.h> > #include <linux/kallsyms.h> > #include <linux/list.h> > @@ -36,6 +37,12 @@ > #include <asm/tlbflush.h> > #include <asm/shmparam.h> > > +#ifdef CONFIG_X86 > +#include <asm/page_types.h> > +#include <asm/setup.h> > +#include <asm/kaslr_modules.h> > +#endif > + > #include "internal.h" > > struct vfree_deferred { > @@ -2919,7 +2926,96 @@ static int __init proc_vmalloc_init(void) > proc_create_seq("vmallocinfo", 0400, NULL, &vmalloc_op); > return 0; > } > -module_init(proc_vmalloc_init); > +#elif defined(CONFIG_DEBUG_FS) > +static int __init proc_vmalloc_init(void) > +{ > + return 0; > +} > +#endif > > +#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_RANDOMIZE_FINE_MODULE) > +static inline unsigned long is_in_backup(unsigned long addr) > +{ > + return addr >= MODULES_VADDR + get_modules_rand_len(); > +} > + > +static int modulefraginfo_debug_show(struct seq_file *m, void *v) > +{ > + unsigned long last_end = MODULES_VADDR; > + unsigned long total_free = 0; > + unsigned long largest_free = 0; > + unsigned long backup_cnt = 0; > + unsigned long gap; > + struct vmap_area *prev, *cur = NULL; > + > + spin_lock(&vmap_area_lock); > + > + if (!pvm_find_next_prev(MODULES_VADDR, &cur, &prev) || !cur) > + goto done; > + > + for (; cur->va_end <= MODULES_END; cur = list_next_entry(cur, list)) > { > + /* Don't count areas that are marked to be lazily freed */ > + if (!(cur->flags & VM_LAZY_FREE)) { > + if (kaslr_mod_randomize_each_module()) > + backup_cnt += is_in_backup(cur->va_start); > + gap = cur->va_start - last_end; > + if (gap > largest_free) > + largest_free = gap; > + total_free += gap; > + last_end = cur->va_end; > + } > + > + if (list_is_last(&cur->list, &vmap_area_list)) > + break; > + } > + > +done: > + gap = (MODULES_END - last_end); > + if (gap > largest_free) > + largest_free = gap; > + total_free += gap; > + > + spin_unlock(&vmap_area_lock); > + > + seq_printf(m, "\tLargest free space:\t%lu kB\n", largest_free / > 1024); > + seq_printf(m, "\t Total free space:\t%lu kB\n", total_free / 1024); > + > + if (kaslr_mod_randomize_each_module()) > + seq_printf(m, "Allocations in backup area:\t%lu\n", > backup_cnt); > + > + return 0; > +} > + > +static int proc_module_frag_debug_open(struct inode *inode, struct file > *file) > +{ > + return single_open(file, modulefraginfo_debug_show, NULL); > +} > + > +static const struct file_operations debug_module_frag_operations = { > + .open = proc_module_frag_debug_open, > + .read = seq_read, > + .llseek = seq_lseek, > + .release = single_release, > +}; > + > +static void __init debug_modfrag_init(void) > +{ > + debugfs_create_file("modfraginfo", 0400, NULL, NULL, > + &debug_module_frag_operations); > +} > +#elif defined(CONFIG_DEBUG_FS) || defined(CONFIG_PROC_FS) > +static void __init debug_modfrag_init(void) > +{ > +} > #endif > > +#if defined(CONFIG_DEBUG_FS) || defined(CONFIG_PROC_FS) > +static int __init info_vmalloc_init(void) > +{ > + proc_vmalloc_init(); > + debug_modfrag_init(); > + return 0; > +} > + > +module_init(info_vmalloc_init); > +#endif
