| 12 Nov 2025 |
 Mic92 | * Is riscv 4k page aligned? Usually the first page should not be mapped in userspace | 06:06:36 |
| Mic92 | Not sure if this is your thing, but llms are pretty good at having read all of the cpu architecture specs and have found in the past for me pretty quickly oddities in readelf. | 06:09:20 |
 Tristan Ross | I've been rubber ducking ChatGPT since Sunday with this problem | 06:09:44 |
| Tristan Ross | It believe AppArmor is the problem, despite me disabling it thinking that was the problem | 06:10:10 |
| Mic92 | Feels unlikely. | 06:10:53 |
| Mic92 | You would see the audit log in dmesg | 06:11:16 |
| Tristan Ross | Yeah, which I don't but ChatGPT is just confident it's AppArmor lol | 06:11:33 |
| Mic92 | It's definitely the mmap syscall requesting that returns eperm | 06:12:33 |
| Mic92 | You could even ask it to write an mmap call on these parameters to reproduce it | 06:13:30 |
| Mic92 | I just don't know which load segment is off. My brain cannot parse these unaligned columns from the phone | 06:14:34 |
| Tristan Ross | $ zcat /proc/config.gz | grep CONFIG_STRICT_KERNEL_RWX
CONFIG_STRICT_KERNEL_RWX=y
Could this be a problem?
| 06:14:54 |
| Tristan Ross | ChatGPT says it could be lol | 06:15:06 |
| Mic92 | No we don't map as executable here if i interpret correctly | 06:16:06 |
| Mic92 |
mmap(0xf000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0) = -1 EPERM (Operation not permitted) | 06:16:19 |
| Mic92 | Only read/write | 06:16:32 |
| Mic92 | Figure out what 3 is here | 06:16:59 |
| Mic92 | Run strace with -yy | 06:17:15 |
 dramforever | 0xf000 is sus | 06:17:29 |
| Mic92 | This gives you file descriptors | 06:17:33 |
| dramforever | is it below the minimum address limit | 06:17:38 |
| Mic92 | In reply to @dramforever:matrix.org
0xf000 is sus I agree | 06:17:47 |
| Mic92 | What's allowed on RISC-V? | 06:18:05 |
| Tristan Ross | I set sudo sysctl -w vm.mmap_min_addr=4096 and GCC works | 06:18:15 |
| dramforever | the other thing is it may be relevant to us enabling PIE recently | 06:18:41 |
| dramforever | ish | 06:18:45 |
| dramforever | recent-ish | 06:18:49 |
| dramforever | i'm starting to think maybe you shouldn't be on 6.6 | 06:19:14 |
| Tristan Ross | The bootstrap-tools GCC is from last year, I thought PIE was within the last couple months | 06:19:14 |
| dramforever | although it really also shouldn't be breaking | 06:19:35 |
| Mic92 | Check if the binary is supposes to be relocatable with checkseck | 06:19:44 |
