On Mon, 2023-08-07 at 11:17 -0700, Richard Henderson wrote: > On 8/7/23 09:37, Richard Henderson wrote: > > We will want to be able to search the set of mappings. > > For this patch, the two users iterate the tree in order. > > > > Signed-off-by: Richard Henderson <richard.hender...@linaro.org> > > --- > > include/qemu/selfmap.h | 20 ++++---- > > linux-user/elfload.c | 14 +++-- > > linux-user/syscall.c | 15 +++--- > > util/selfmap.c | 114 +++++++++++++++++++++++++----------- > > ----- > > 4 files changed, 96 insertions(+), 67 deletions(-) > > I should note that, for 8.2, this will enable a rewrite of > open_self_maps_1 so that it > does not require page-by-page checking of page_get_flags. > > My idea is that open_self_maps_1 would use walk_memory_regions to see > all guest memory > regions. The per-region callback would cross-check with the host- > region interval tree to > find the dev+inode+path. > > Cc Ilya and Helge, since there are two outstanding changes to > open_self_maps. > > > r~
My outstanding change should not be sensitive to this; it should be possible to put it in both before or after the rewrite. I really like this idea though, since I looked into ppc64le and there printing maps is quite broken: it's not just that QEMU can't determine the names of the mapped files, but also a number of regions are simply missing. This also affects core dumps generated by GDB attached to gdbstub. For example, cat /proc/self/maps has the following internal page layout: start end size prot 0000000010000000-000000001000d000 000000000000d000 r-x 000000001000d000-0000000010010000 0000000000003000 --- 0000000010010000-000000001001f000 000000000000f000 r-- 000000001001f000-0000000010020000 0000000000001000 r-- 0000000010020000-0000000010021000 0000000000001000 rw- 0000100000000000-0000100000010000 0000000000010000 --- 0000100000010000-0000100000810000 0000000000800000 rw- 0000100000810000-0000100000830000 0000000000020000 r-x 0000100000830000-000010000083d000 000000000000d000 r-x 000010000083d000-0000100000840000 0000000000003000 --- 0000100000840000-000010000084f000 000000000000f000 r-- 000010000084f000-0000100000850000 0000000000001000 r-- 0000100000850000-0000100000851000 0000000000001000 rw- 0000100000851000-0000100000852000 0000000000001000 rw- 0000100000860000-0000100000861000 0000000000001000 r-x 0000100000880000-0000100000a50000 00000000001d0000 r-x 0000100000a50000-0000100000a60000 0000000000010000 r-- 0000100000a60000-0000100000a70000 0000000000010000 rw- 0000100000a70000-0000100000b70000 0000000000100000 rw- 0000100000b70000-000010000742d000 00000000068bd000 r-- 00007fffb22b0000-00007fffb22e0000 0000000000030000 rw- but prints only: 100000000000-100000010000 ---p 00000000 00:00 0 100000010000-100000810000 rw-p 00000000 00:00 0 [stack] 100000810000-100000830000 r-xp 00000000 fd:00 3049136 /usr/lib64/ld-2.17.so 100000880000-100000a50000 r-xp 00000000 fd:00 3017372 /usr/lib64/libc-2.17.so 100000a50000-100000a60000 r--p 001c0000 fd:00 3017372 /usr/lib64/libc-2.17.so 100000a60000-100000a70000 rw-p 001d0000 fd:00 3017372 /usr/lib64/libc-2.17.so 100000a70000-100000b70000 rw-p 00000000 00:00 0 7fffb22b0000-7fffb22e0000 rw-p 00000000 00:00 0 I don't see a good way to prevent page_check_range() from rejecting most of the mappings with the current code structure, but I think that after the proposed rewrite it should begin to just work.
