Le 28/03/2024 à 07:52, Christophe Leroy a écrit :

Le 28/03/2024 à 05:55, Rohan McLure a écrit :

quoted

Support page table check on all PowerPC platforms. This works by
serialising assignments, reassignments and clears of page table
entries at each level in order to ensure that anonymous mappings
have at most one writable consumer, and likewise that file-backed
mappings are not simultaneously also anonymous mappings.

In order to support this infrastructure, a number of stubs must be
defined for all powerpc platforms. Additionally, seperate set_pte_at()
and set_pte_at_unchecked(), to allow for internal, uninstrumented 
mappings.

I gave it a try on QEMU e500 (64 bits), and get the following Oops. What 
do I have to look for ?

Freeing unused kernel image (initmem) memory: 2588K
This architecture does not have kernel memory protection.
Run /init as init process
------------[ cut here ]------------
kernel BUG at mm/page_table_check.c:119!
Oops: Exception in kernel mode, sig: 5 [#1]
BE PAGE_SIZE=4K SMP NR_CPUS=32 QEMU e500

Same problem on my 8xx board:

[    7.358146] Freeing unused kernel image (initmem) memory: 448K
[    7.363957] Run /init as init process
[    7.370955] ------------[ cut here ]------------
[    7.375411] kernel BUG at mm/page_table_check.c:119!
[    7.380393] Oops: Exception in kernel mode, sig: 5 [#1]
[    7.385621] BE PAGE_SIZE=16K PREEMPT CMPC885
[    7.393483] CPU: 0 PID: 1 Comm: init Not tainted 
6.8.0-s3k-dev-13737-g8d9e247585fb #787
[    7.401505] Hardware name: MIAE 8xx 0x500000 CMPC885
[    7.406481] NIP:  c0183278 LR: c018316c CTR: 00000001
[    7.411541] REGS: c902bb20 TRAP: 0700   Not tainted 
(6.8.0-s3k-dev-13737-g8d9e247585fb)
[    7.419657] MSR:  00029032 <EE,ME,IR,DR,RI>  CR: 35055355  XER: 80007100
[    7.426550]
[    7.426550] GPR00: c018316c c902bbe0 c2118000 c7f7a0d8 7fab8000 
c23b5ae0 c902bc20 00000002
[    7.426550] GPR08: c11a0000 c7f7a0d8 c11143e0 00000000 95003355 
00000000 c0004a38 c23a0a00
[    7.426550] GPR16: 00004000 7fffc000 80000000 c23a0a00 00000001 
7fab8000 ffabc000 80000000
[    7.426550] GPR24: 7fffc000 c33be1c0 00004000 c902bc20 7fab8000 
00000001 c7fb0360 00000000
[    7.463291] NIP [c0183278] __page_table_check_ptes_set+0x1c8/0x210
[    7.469491] LR [c018316c] __page_table_check_ptes_set+0xbc/0x210
[    7.475514] Call Trace:
[    7.477957] [c902bbe0] [c018316c] 
__page_table_check_ptes_set+0xbc/0x210 (unreliable)
[    7.485809] [c902bc00] [c0012474] set_ptes+0x148/0x16c
[    7.490958] [c902bc50] [c0158a3c] move_page_tables+0x228/0x578
[    7.496806] [c902bcf0] [c0192f38] shift_arg_pages+0xf0/0x1d4
[    7.502479] [c902bd90] [c0193b40] setup_arg_pages+0x1c8/0x36c
[    7.508238] [c902be40] [c01f51a0] load_elf_binary+0x3c0/0x1218
[    7.514086] [c902beb0] [c01934b0] bprm_execve+0x21c/0x4a4
[    7.519497] [c902bf00] [c019516c] kernel_execve+0x13c/0x200
[    7.525082] [c902bf20] [c0004aa8] kernel_init+0x70/0x1b0
[    7.530406] [c902bf30] [c00111e4] ret_from_kernel_user_thread+0x10/0x18
[    7.537038] --- interrupt: 0 at 0x0
[    7.540534] Code: 39290004 7ce04828 30e70001 7ce0492d 40a2fff4 
2c070000 4080ff94 0fe00000 0fe00000 0fe00000 2c1f0000 4082ff80 
<0fe00000> 0fe00000 392affff 4bfffef8
[    7.556068] ---[ end trace 0000000000000000 ]---
[    7.560692]
[    8.531997] note: init[1] exited with irqs disabled
[    8.536891] note: init[1] exited with preempt_count 1
[    8.542032] Kernel panic - not syncing: Attempted to kill init! 
exitcode=0x00000005
[    8.549602] Rebooting in 180 seconds..