Hi Max,
On 13/8/24 04:02, Max Filippov wrote:
Hi Greg,
On Sun, Aug 11, 2024 at 7:26 PM Greg Ungerer <gregungerer@xxxxxxxxxxxxxx> wrote:
On 23/3/24 05:54, Max Filippov wrote:
Althought FDPIC linux kernel provides /proc/<pid>/auxv files they are
empty because there's no code that initializes mm->saved_auxv in the
FDPIC ELF loader.
Synchronize FDPIC ELF aux vector setup with ELF. Replace entry-by-entry
aux vector copying to userspace with initialization of mm->saved_auxv
first and then copying it to userspace as a whole.
Signed-off-by: Max Filippov <jcmvbkbc@xxxxxxxxx>
This is breaking ARM nommu builds supporting fdpic and elf binaries for me.
Tests I have for m68k and riscv nommu setups running elf binaries
don't show any problems - I am only seeing this on ARM.
...
Freeing unused kernel image (initmem) memory: 472K
This architecture does not have kernel memory protection.
Run /init as init process
Internal error: Oops - undefined instruction: 0 [#1] ARM
Modules linked in:
CPU: 0 PID: 1 Comm: init Not tainted 6.10.0 #1
Hardware name: ARM-Versatile (Device Tree Support)
PC is at load_elf_fdpic_binary+0xb34/0xb80
LR is at 0x0
pc : [<00109ce8>] lr : [<00000000>] psr: 80000153
sp : 00823e40 ip : 00000000 fp : 00b8fee4
r10: 009c9b80 r9 : 00b8ff80 r8 : 009ee800
r7 : 00000000 r6 : 009f7e80 r5 : 00b8fedc r4 : 00b87000
r3 : 00b8fed8 r2 : 00b8fee0 r1 : 00b87128 r0 : 00b8fef0
Flags: Nzcv IRQs on FIQs off Mode SVC_32 ISA ARM Segment none
Control: 00091176 Table: 00000000 DAC: 00000000
Register r0 information: non-slab/vmalloc memory
Register r1 information: slab/vmalloc mm_struct start 00b87000 pointer offset 296 size 428
Register r2 information: non-slab/vmalloc memory
Register r3 information: non-slab/vmalloc memory
Register r4 information: slab/vmalloc mm_struct start 00b87000 pointer offset 0 size 428
Register r5 information: non-slab/vmalloc memory
Register r6 information: slab/vmalloc kmalloc-32 start 009f7e80 pointer offset 0 size 32
Register r7 information: non-slab/vmalloc memory
Register r8 information: slab/vmalloc kmalloc-512 start 009ee800 pointer offset 0 size 512
Register r9 information: non-slab/vmalloc memory
Register r10 information: slab/vmalloc kmalloc-128 start 009c9b80 pointer offset 0 size 128
Register r11 information: non-slab/vmalloc memory
Register r12 information: non-slab/vmalloc memory
Process init (pid: 1, stack limit = 0x(ptrval))
Stack: (0x00823e40 to 0x00824000)
3e40: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3e60: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3e80: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3ea0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3ec0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3ee0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3f00: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3f20: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3f40: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3f60: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3f80: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3fa0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3fc0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3fe0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
Call trace:
load_elf_fdpic_binary from bprm_execve+0x1b4/0x488
bprm_execve from kernel_execve+0x154/0x1e4
kernel_execve from kernel_init+0x4c/0x108
kernel_init from ret_from_fork+0x14/0x38
Exception stack(0x00823fb0 to 0x00823ff8)
3fa0: ???????? ???????? ???????? ????????
3fc0: ???????? ???????? ???????? ???????? ???????? ???????? ???????? ????????
3fe0: ???????? ???????? ???????? ???????? ???????? ????????
Code: bad PC value
---[ end trace 0000000000000000 ]---
note: init[1] exited with irqs disabled
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---
The code around that PC is:
109cd0: e2833ff1 add r3, r3, #964 @ 0x3c4
109cd4: e5933000 ldr r3, [r3]
109cd8: e5933328 ldr r3, [r3, #808] @ 0x328
109cdc: e5933084 ldr r3, [r3, #132] @ 0x84
109ce0: e5843034 str r3, [r4, #52] @ 0x34
109ce4: eafffdbc b 1093dc <load_elf_fdpic_binary+0x228>
109ce8: e7f001f2 .word 0xe7f001f2
109cec: eb09471d bl 35b968 <__stack_chk_fail>
109cf0: e59f0038 ldr r0, [pc, #56] @ 109d30 <load_elf_fdpic_binary+0xb7c>
109cf4: eb092f03 bl 355908 <_printk>
109cf8: eafffdb7 b 1093dc <load_elf_fdpic_binary+0x228>
Reverting just this change gets it working again.
Any idea what might be going on?
Other than that the layout of the aux vector has slightly changed I don't
see anything. I can take a look at what's going on if you can share the
reproducer.
I build the test binary using a simple script:
https://github.com/gregungerer/simple-linux/blob/master/build-armnommu-linux-uclibc-fdpic.sh
Run the resulting vmlinux and devicetree under qemu as per comments at top of that script.
Note that that script has a revert of this change (at line 191), so you would need
to take that out to reproduce the problem. This script will look for a couple of
configs and a versatile patch:
https://github.com/gregungerer/simple-linux/blob/master/configs/linux-6.10-armnommu-versatile.config
https://github.com/gregungerer/simple-linux/blob/master/configs/uClibc-ng-1.0.49-armnommu-fdpic.config
https://github.com/gregungerer/simple-linux/blob/master/configs/busybox-1.36.1.config
https://github.com/gregungerer/simple-linux/blob/master/configs/rootfs.dev
https://github.com/gregungerer/simple-linux/blob/master/patches/linux-6.10-armnommu-versatile.patch
https://github.com/gregungerer/simple-linux/blob/master/patches/linux-6.10-binfmt_elf_fdpic-fix-proc-pid-auxv.patch
Or you could just clone the whole small set in one step from:
https://github.com/gregungerer/simple-linux.git
If you need to me to run something I can do that easily too.
Regards
Greg
