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Diffstat (limited to 'compat/backport-4.0.c')
| -rw-r--r-- | compat/backport-4.0.c | 377 |
1 files changed, 377 insertions, 0 deletions
diff --git a/compat/backport-4.0.c b/compat/backport-4.0.c new file mode 100644 index 0000000..eb95082 --- /dev/null +++ b/compat/backport-4.0.c @@ -0,0 +1,377 @@ +/* + * Copyright (c) 2015 Hauke Mehrtens <hauke@hauke-m.de> + * + * Backport functionality introduced in Linux 4.0. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/sched.h> +#include <linux/ctype.h> +#include <linux/printk.h> +#include <linux/export.h> +#include <linux/trace_seq.h> +#include <linux/ftrace_event.h> +#include <asm/unaligned.h> + +static __always_inline long __get_user_pages_locked(struct task_struct *tsk, + struct mm_struct *mm, + unsigned long start, + unsigned long nr_pages, + int write, int force, + struct page **pages, + struct vm_area_struct **vmas, + int *locked, bool notify_drop, + unsigned int flags) +{ + long ret, pages_done; + bool lock_dropped; + + if (locked) { + /* if VM_FAULT_RETRY can be returned, vmas become invalid */ + BUG_ON(vmas); + /* check caller initialized locked */ + BUG_ON(*locked != 1); + } + + if (pages) + flags |= FOLL_GET; + if (write) + flags |= FOLL_WRITE; + if (force) + flags |= FOLL_FORCE; + + pages_done = 0; + lock_dropped = false; + for (;;) { + ret = __get_user_pages(tsk, mm, start, nr_pages, flags, pages, + vmas, locked); + if (!locked) + /* VM_FAULT_RETRY couldn't trigger, bypass */ + return ret; + + /* VM_FAULT_RETRY cannot return errors */ + if (!*locked) { + BUG_ON(ret < 0); + BUG_ON(ret >= nr_pages); + } + + if (!pages) + /* If it's a prefault don't insist harder */ + return ret; + + if (ret > 0) { + nr_pages -= ret; + pages_done += ret; + if (!nr_pages) + break; + } + if (*locked) { + /* VM_FAULT_RETRY didn't trigger */ + if (!pages_done) + pages_done = ret; + break; + } + /* VM_FAULT_RETRY triggered, so seek to the faulting offset */ + pages += ret; + start += ret << PAGE_SHIFT; + + /* + * Repeat on the address that fired VM_FAULT_RETRY + * without FAULT_FLAG_ALLOW_RETRY but with + * FAULT_FLAG_TRIED. + */ + *locked = 1; + lock_dropped = true; + down_read(&mm->mmap_sem); + ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED, + pages, NULL, NULL); + if (ret != 1) { + BUG_ON(ret > 1); + if (!pages_done) + pages_done = ret; + break; + } + nr_pages--; + pages_done++; + if (!nr_pages) + break; + pages++; + start += PAGE_SIZE; + } + if (notify_drop && lock_dropped && *locked) { + /* + * We must let the caller know we temporarily dropped the lock + * and so the critical section protected by it was lost. + */ + up_read(&mm->mmap_sem); + *locked = 0; + } + return pages_done; +} + +/* + * We can leverage the VM_FAULT_RETRY functionality in the page fault + * paths better by using either get_user_pages_locked() or + * get_user_pages_unlocked(). + * + * get_user_pages_locked() is suitable to replace the form: + * + * down_read(&mm->mmap_sem); + * do_something() + * get_user_pages(tsk, mm, ..., pages, NULL); + * up_read(&mm->mmap_sem); + * + * to: + * + * int locked = 1; + * down_read(&mm->mmap_sem); + * do_something() + * get_user_pages_locked(tsk, mm, ..., pages, &locked); + * if (locked) + * up_read(&mm->mmap_sem); + */ +long get_user_pages_locked(unsigned long start, unsigned long nr_pages, + int write, int force, struct page **pages, + int *locked) +{ + return __get_user_pages_locked(current, current->mm, start, nr_pages, + write, force, pages, NULL, locked, true, + FOLL_TOUCH); +} +EXPORT_SYMBOL_GPL(get_user_pages_locked); + +/* + * Same as get_user_pages_unlocked(...., FOLL_TOUCH) but it allows to + * pass additional gup_flags as last parameter (like FOLL_HWPOISON). + * + * NOTE: here FOLL_TOUCH is not set implicitly and must be set by the + * caller if required (just like with __get_user_pages). "FOLL_GET", + * "FOLL_WRITE" and "FOLL_FORCE" are set implicitly as needed + * according to the parameters "pages", "write", "force" + * respectively. + */ +static __always_inline long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, + unsigned long start, unsigned long nr_pages, + int write, int force, struct page **pages, + unsigned int gup_flags) +{ + long ret; + int locked = 1; + down_read(&mm->mmap_sem); + ret = __get_user_pages_locked(tsk, mm, start, nr_pages, write, force, + pages, NULL, &locked, false, gup_flags); + if (locked) + up_read(&mm->mmap_sem); + return ret; +} + +/* + * get_user_pages_unlocked() is suitable to replace the form: + * + * down_read(&mm->mmap_sem); + * get_user_pages(tsk, mm, ..., pages, NULL); + * up_read(&mm->mmap_sem); + * + * with: + * + * get_user_pages_unlocked(tsk, mm, ..., pages); + * + * It is functionally equivalent to get_user_pages_fast so + * get_user_pages_fast should be used instead, if the two parameters + * "tsk" and "mm" are respectively equal to current and current->mm, + * or if "force" shall be set to 1 (get_user_pages_fast misses the + * "force" parameter). + */ +long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, + int write, int force, struct page **pages) +{ + return __get_user_pages_unlocked(current, current->mm, start, nr_pages, + write, force, pages, FOLL_TOUCH); +} +EXPORT_SYMBOL_GPL(get_user_pages_unlocked); + + +/** + * hex_dump_to_buffer - convert a blob of data to "hex ASCII" in memory + * @buf: data blob to dump + * @len: number of bytes in the @buf + * @rowsize: number of bytes to print per line; must be 16 or 32 + * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1) + * @linebuf: where to put the converted data + * @linebuflen: total size of @linebuf, including space for terminating NUL + * @ascii: include ASCII after the hex output + * + * hex_dump_to_buffer() works on one "line" of output at a time, i.e., + * 16 or 32 bytes of input data converted to hex + ASCII output. + * + * Given a buffer of u8 data, hex_dump_to_buffer() converts the input data + * to a hex + ASCII dump at the supplied memory location. + * The converted output is always NUL-terminated. + * + * E.g.: + * hex_dump_to_buffer(frame->data, frame->len, 16, 1, + * linebuf, sizeof(linebuf), true); + * + * example output buffer: + * 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO + * + * Return: + * The amount of bytes placed in the buffer without terminating NUL. If the + * output was truncated, then the return value is the number of bytes + * (excluding the terminating NUL) which would have been written to the final + * string if enough space had been available. + */ +int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize, + char *linebuf, size_t linebuflen, bool ascii) +{ + const u8 *ptr = buf; + int ngroups; + u8 ch; + int j, lx = 0; + int ascii_column; + int ret; + + if (rowsize != 16 && rowsize != 32) + rowsize = 16; + + if (len > rowsize) /* limit to one line at a time */ + len = rowsize; + if (!is_power_of_2(groupsize) || groupsize > 8) + groupsize = 1; + if ((len % groupsize) != 0) /* no mixed size output */ + groupsize = 1; + + ngroups = len / groupsize; + ascii_column = rowsize * 2 + rowsize / groupsize + 1; + + if (!linebuflen) + goto overflow1; + + if (!len) + goto nil; + + if (groupsize == 8) { + const u64 *ptr8 = buf; + + for (j = 0; j < ngroups; j++) { + ret = snprintf(linebuf + lx, linebuflen - lx, + "%s%16.16llx", j ? " " : "", + get_unaligned(ptr8 + j)); + if (ret >= linebuflen - lx) + goto overflow1; + lx += ret; + } + } else if (groupsize == 4) { + const u32 *ptr4 = buf; + + for (j = 0; j < ngroups; j++) { + ret = snprintf(linebuf + lx, linebuflen - lx, + "%s%8.8x", j ? " " : "", + get_unaligned(ptr4 + j)); + if (ret >= linebuflen - lx) + goto overflow1; + lx += ret; + } + } else if (groupsize == 2) { + const u16 *ptr2 = buf; + + for (j = 0; j < ngroups; j++) { + ret = snprintf(linebuf + lx, linebuflen - lx, + "%s%4.4x", j ? " " : "", + get_unaligned(ptr2 + j)); + if (ret >= linebuflen - lx) + goto overflow1; + lx += ret; + } + } else { + for (j = 0; j < len; j++) { + if (linebuflen < lx + 3) + goto overflow2; + ch = ptr[j]; + linebuf[lx++] = hex_asc_hi(ch); + linebuf[lx++] = hex_asc_lo(ch); + linebuf[lx++] = ' '; + } + if (j) + lx--; + } + if (!ascii) + goto nil; + + while (lx < ascii_column) { + if (linebuflen < lx + 2) + goto overflow2; + linebuf[lx++] = ' '; + } + for (j = 0; j < len; j++) { + if (linebuflen < lx + 2) + goto overflow2; + ch = ptr[j]; + linebuf[lx++] = (isascii(ch) && isprint(ch)) ? ch : '.'; + } +nil: + linebuf[lx] = '\0'; + return lx; +overflow2: + linebuf[lx++] = '\0'; +overflow1: + return ascii ? ascii_column + len : (groupsize * 2 + 1) * ngroups - 1; +} +EXPORT_SYMBOL_GPL(hex_dump_to_buffer); + +#if LINUX_VERSION_IS_LESS(3,17,0) +static inline unsigned char * +trace_seq_buffer_ptr(struct trace_seq *s) +{ + return s->buffer + s->len; +} +#endif + +const char * +ftrace_print_array_seq(struct trace_seq *p, const void *buf, int buf_len, + size_t el_size) +{ + const char *ret = trace_seq_buffer_ptr(p); + const char *prefix = ""; + void *ptr = (void *)buf; + + trace_seq_putc(p, '{'); + + while (ptr < buf + buf_len) { + switch (el_size) { + case 1: + trace_seq_printf(p, "%s0x%x", prefix, + *(u8 *)ptr); + break; + case 2: + trace_seq_printf(p, "%s0x%x", prefix, + *(u16 *)ptr); + break; + case 4: + trace_seq_printf(p, "%s0x%x", prefix, + *(u32 *)ptr); + break; + case 8: + trace_seq_printf(p, "%s0x%llx", prefix, + *(u64 *)ptr); + break; + default: + trace_seq_printf(p, "BAD SIZE:%zu 0x%x", el_size, + *(u8 *)ptr); + el_size = 1; + } + prefix = ","; + ptr += el_size; + } + + trace_seq_putc(p, '}'); + trace_seq_putc(p, 0); + + return ret; +} +EXPORT_SYMBOL(ftrace_print_array_seq); |