diff options
Diffstat (limited to 'fs/coredump.c')
| -rw-r--r-- | fs/coredump.c | 46 |
1 files changed, 42 insertions, 4 deletions
diff --git a/fs/coredump.c b/fs/coredump.c index 9d235fa14a..be6403b4b1 100644 --- a/fs/coredump.c +++ b/fs/coredump.c @@ -872,6 +872,9 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page) loff_t pos; ssize_t n; + if (!page) + return 0; + if (cprm->to_skip) { if (!__dump_skip(cprm, cprm->to_skip)) return 0; @@ -884,7 +887,6 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page) pos = file->f_pos; bvec_set_page(&bvec, page, PAGE_SIZE, 0); iov_iter_bvec(&iter, ITER_SOURCE, &bvec, 1, PAGE_SIZE); - iov_iter_set_copy_mc(&iter); n = __kernel_write_iter(cprm->file, &iter, &pos); if (n != PAGE_SIZE) return 0; @@ -895,10 +897,44 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page) return 1; } +/* + * If we might get machine checks from kernel accesses during the + * core dump, let's get those errors early rather than during the + * IO. This is not performance-critical enough to warrant having + * all the machine check logic in the iovec paths. + */ +#ifdef copy_mc_to_kernel + +#define dump_page_alloc() alloc_page(GFP_KERNEL) +#define dump_page_free(x) __free_page(x) +static struct page *dump_page_copy(struct page *src, struct page *dst) +{ + void *buf = kmap_local_page(src); + size_t left = copy_mc_to_kernel(page_address(dst), buf, PAGE_SIZE); + kunmap_local(buf); + return left ? NULL : dst; +} + +#else + +/* We just want to return non-NULL; it's never used. */ +#define dump_page_alloc() ERR_PTR(-EINVAL) +#define dump_page_free(x) ((void)(x)) +static inline struct page *dump_page_copy(struct page *src, struct page *dst) +{ + return src; +} +#endif + int dump_user_range(struct coredump_params *cprm, unsigned long start, unsigned long len) { unsigned long addr; + struct page *dump_page; + + dump_page = dump_page_alloc(); + if (!dump_page) + return 0; for (addr = start; addr < start + len; addr += PAGE_SIZE) { struct page *page; @@ -912,14 +948,17 @@ int dump_user_range(struct coredump_params *cprm, unsigned long start, */ page = get_dump_page(addr); if (page) { - int stop = !dump_emit_page(cprm, page); + int stop = !dump_emit_page(cprm, dump_page_copy(page, dump_page)); put_page(page); - if (stop) + if (stop) { + dump_page_free(dump_page); return 0; + } } else { dump_skip(cprm, PAGE_SIZE); } } + dump_page_free(dump_page); return 1; } #endif @@ -981,7 +1020,6 @@ static struct ctl_table coredump_sysctls[] = { .mode = 0644, .proc_handler = proc_dointvec, }, - { } }; static int __init init_fs_coredump_sysctls(void) |