On Mon, Aug 12, 2024 at 9:53 PM Greg Ungerer <gregungerer@xxxxxxxxxxxxxx> wrote: > On 13/8/24 04:02, Max Filippov wrote: > > 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. Cool scripts, thanks. I was able to reproduce the issue, it's the BUG_ON(csp != sp); from the create_elf_fdpic_tables() that causes it. I'm still trying to figure out how that happens. -- Thanks. -- Max
