113 lines
3.7 KiB
Diff
113 lines
3.7 KiB
Diff
From 4404368a0860e3b6c845eb41782e97a9bf7593b8 Mon Sep 17 00:00:00 2001
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From: WANG Chao <chaowang@redhat.com>
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Date: Wed, 18 Dec 2013 22:34:43 +0900
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Subject: [PATCH] [PATCH] memset() in cyclic bitmap initialization introduce
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segment fault.
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We are using memset() to improve performance when creating 1st and 2nd
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bitmap. After doing round up the pfn_start and round down pfn_end, it's
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possible that pfn_start_roundup is greater than pfn_end_round. A segment
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fault could happen in that case because memset is taking roughly the
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value of (pfn_end_round << 3 - pfn_start_roundup << 3 ), which is
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negative, as its third argument.
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So we can skip the memset if start is greater than end. It's safe
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because we will set bit for the round up part and also round down part.
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Actually this happens on my EFI virtual machine:
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cat /proc/iomem:
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00000000-00000fff : reserved
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00001000-0009ffff : System RAM
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000a0000-000bffff : PCI Bus 0000:00
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000f0000-000fffff : System ROM
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00100000-3d162017 : System RAM
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01000000-015cab9b : Kernel code
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015cab9c-019beb3f : Kernel data
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01b4f000-01da9fff : Kernel bss
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30000000-37ffffff : Crash kernel
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3d162018-3d171e57 : System RAM
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3d171e58-3d172017 : System RAM
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3d172018-3d17ae57 : System RAM
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3d17ae58-3dc10fff : System RAM
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3dc11000-3dc18fff : reserved
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3dc19000-3dc41fff : System RAM
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3dc42000-3ddcefff : reserved
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3ddcf000-3f7fefff : System RAM
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3f7ff000-3f856fff : reserved
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[..]
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gdb ./makedumpfile core
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(gdb) bt full
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[..]
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#1 0x000000000042775d in create_1st_bitmap_cyclic () at makedumpfile.c:4543
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i = 0x5
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pfn = 0x3d190
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phys_start = 0x3d18ee58
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phys_end = 0x3d18f018
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pfn_start = 0x3d18e
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pfn_end = 0x3d18f
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pfn_start_roundup = 0x3d190
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pfn_end_round = 0x3d188
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pfn_start_byte = 0x7a32
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pfn_end_byte = 0x7a31
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[..]
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(gdb) list makedumpfile.c:4543
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4538 return FALSE;
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4539
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4540 pfn_start_byte = (pfn_start_roundup - info->cyclic_start_pfn) >>
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3;
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4541 pfn_end_byte = (pfn_end_round - info->cyclic_start_pfn) >> 3;
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4542
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4543 memset(info->partial_bitmap2 + pfn_start_byte,
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4544 0xff,
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4545 pfn_end_byte - pfn_start_byte);
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4546
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4547 for (pfn = pfn_end_round; pfn < pfn_end; ++pfn)
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Signed-off-by: WANG Chao <chaowang@redhat.com>
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---
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makedumpfile.c | 18 +++++++++++-------
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1 file changed, 11 insertions(+), 7 deletions(-)
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diff --git a/makedumpfile.c b/makedumpfile.c
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index 23251a1..ef08d91 100644
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--- a/makedumpfile-1.5.5/makedumpfile.c
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+++ b/makedumpfile-1.5.5/makedumpfile.c
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@@ -4435,11 +4435,13 @@ create_1st_bitmap_cyclic()
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pfn_start_byte = (pfn_start_roundup - info->cyclic_start_pfn) >> 3;
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pfn_end_byte = (pfn_end_round - info->cyclic_start_pfn) >> 3;
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- memset(info->partial_bitmap1 + pfn_start_byte,
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- 0xff,
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- pfn_end_byte - pfn_start_byte);
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+ if (pfn_start_byte < pfn_end_byte) {
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+ memset(info->partial_bitmap1 + pfn_start_byte,
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+ 0xff,
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+ pfn_end_byte - pfn_start_byte);
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- pfn_bitmap1 += (pfn_end_byte - pfn_start_byte) * BITPERBYTE;
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+ pfn_bitmap1 += (pfn_end_byte - pfn_start_byte) * BITPERBYTE;
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+ }
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for (pfn = pfn_end_round; pfn < pfn_end; pfn++) {
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if (set_bit_on_1st_bitmap(pfn))
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@@ -4540,9 +4542,11 @@ initialize_2nd_bitmap_cyclic(void)
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pfn_start_byte = (pfn_start_roundup - info->cyclic_start_pfn) >> 3;
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pfn_end_byte = (pfn_end_round - info->cyclic_start_pfn) >> 3;
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- memset(info->partial_bitmap2 + pfn_start_byte,
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- 0xff,
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- pfn_end_byte - pfn_start_byte);
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+ if (pfn_start_byte < pfn_end_byte) {
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+ memset(info->partial_bitmap2 + pfn_start_byte,
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+ 0xff,
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+ pfn_end_byte - pfn_start_byte);
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+ }
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for (pfn = pfn_end_round; pfn < pfn_end; ++pfn)
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if (!set_bit_on_2nd_bitmap_for_kernel(pfn))
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--
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1.8.5.3
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