mirror of
https://github.com/torvalds/linux
synced 2024-11-05 18:23:50 +00:00
09e35a4a1c
Patch series "mm/get_user_pages_fast fixes, cleanups", v2. Turns out get_user_pages_fast and __get_user_pages_fast return different values on error when given a single page: __get_user_pages_fast returns 0. get_user_pages_fast returns either 0 or an error. Callers of get_user_pages_fast expect an error so fix it up to return an error consistently. Stress the difference between get_user_pages_fast and __get_user_pages_fast to make sure callers aren't confused. This patch (of 3): __gup_benchmark_ioctl does not handle the case where get_user_pages_fast fails: - a negative return code will cause a buffer overrun - returning with partial success will cause use of uninitialized memory. [akpm@linux-foundation.org: simplification] Link: http://lkml.kernel.org/r/1522962072-182137-3-git-send-email-mst@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Thorsten Leemhuis <regressions@leemhuis.info> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
102 lines
2.1 KiB
C
102 lines
2.1 KiB
C
#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/ktime.h>
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#include <linux/debugfs.h>
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#define GUP_FAST_BENCHMARK _IOWR('g', 1, struct gup_benchmark)
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struct gup_benchmark {
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__u64 delta_usec;
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__u64 addr;
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__u64 size;
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__u32 nr_pages_per_call;
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__u32 flags;
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};
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static int __gup_benchmark_ioctl(unsigned int cmd,
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struct gup_benchmark *gup)
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{
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ktime_t start_time, end_time;
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unsigned long i, nr, nr_pages, addr, next;
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struct page **pages;
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nr_pages = gup->size / PAGE_SIZE;
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pages = kvzalloc(sizeof(void *) * nr_pages, GFP_KERNEL);
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if (!pages)
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return -ENOMEM;
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i = 0;
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nr = gup->nr_pages_per_call;
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start_time = ktime_get();
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for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) {
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if (nr != gup->nr_pages_per_call)
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break;
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next = addr + nr * PAGE_SIZE;
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if (next > gup->addr + gup->size) {
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next = gup->addr + gup->size;
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nr = (next - addr) / PAGE_SIZE;
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}
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nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i);
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if (nr <= 0)
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break;
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i += nr;
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}
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end_time = ktime_get();
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gup->delta_usec = ktime_us_delta(end_time, start_time);
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gup->size = addr - gup->addr;
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for (i = 0; i < nr_pages; i++) {
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if (!pages[i])
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break;
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put_page(pages[i]);
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}
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kvfree(pages);
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return 0;
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}
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static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
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unsigned long arg)
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{
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struct gup_benchmark gup;
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int ret;
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if (cmd != GUP_FAST_BENCHMARK)
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return -EINVAL;
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if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
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return -EFAULT;
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ret = __gup_benchmark_ioctl(cmd, &gup);
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if (ret)
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return ret;
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if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
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return -EFAULT;
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return 0;
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}
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static const struct file_operations gup_benchmark_fops = {
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.open = nonseekable_open,
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.unlocked_ioctl = gup_benchmark_ioctl,
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};
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static int gup_benchmark_init(void)
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{
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void *ret;
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ret = debugfs_create_file_unsafe("gup_benchmark", 0600, NULL, NULL,
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&gup_benchmark_fops);
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if (!ret)
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pr_warn("Failed to create gup_benchmark in debugfs");
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return 0;
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}
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late_initcall(gup_benchmark_init);
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