binder benchmark causes kernel `BUG` on Raspberry Pi

[TheSven73]

@wedsonaf
(this Issue doesn't really belong here, but I can't open an Issue on wedson's fork)

1. follow rust/kernel: remove config #ifdef in Error.rs file #346 (comment)
2. build for Raspberry Pi: $ make bcm2835_rust_defconfig then switch on binder in defconfig
3. Boot kernel on Raspberry Pi Zero
4. ./ping_server /dev/rust_binder & works great!
5. ./ping_client /dev/rust_binder oopses:

root@raspberrypi:/home/pi# ./ping_client /dev/rust_binder
[  149.443939] ------------[ cut here ]------------
[  149.446521] kernel BUG at rust/helpers.c:14!
[  149.446812] Internal error: Oops - BUG: 0 [#1] ARM
[  149.447165] Modules linked in:
[  149.447946] CPU: 0 PID: 359 Comm: ping_client Tainted: G        W         5.12.0-rc4+ #8
[  149.448448] Hardware name: BCM2835
[  149.448735] PC is at rust_helper_BUG+0x10/0x14
[  149.449441] LR is at rust_begin_unwind+0x4/0x8
[  149.449634] pc : [<c04631b0>]    lr : [<c0462888>]    psr: 00000013
[  149.449919] sp : c404dcc8  ip : c0b80cec  fp : c404dcc8
[  149.450129] r10: c437c0c0  r9 : 00000000  r8 : 49034000
[  149.450341] r7 : c30bed2c  r6 : c30bed00  r5 : c404de58  r4 : c30bed08
[  149.450542] r3 : 00000000  r2 : c404dcf8  r1 : c0b80cec  r0 : c404dcd0
[  149.450853] Flags: nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[  149.451220] Control: 10c53c7d  Table: 04308059  DAC: 00000051
[  149.451421] Process ping_client (pid: 359, stack limit = 0x(ptrval))
[  149.451793] Stack: (0xc404dcc8 to 0xc404e000)
[  149.452278] dcc0:                   c404ddc0 c0462888 c0b20754 c0b22a98 c404dce0 c0b80cec
[  149.452808] dce0: c404dcf8 00000001 00000000 00000000 c0b20754 00000000 c0b7fc00 00000021
[  149.453659] dd00: 00000000 c30bed00 00000000 c404de58 c404dd90 c404ddb8 c437c0d0 c437c0c0
[  149.454648] dd20: c404ddc0 c0749790 c07461ac c404de28 c404dd50 c0233b20 0000000c c404ddc4
[  149.455561] dd40: c404ddd0 c404ddcc c404de84 c404de38 c404de30 c404de14 c404de04 c404de5c
[  149.456404] dd60: c404de60 c404dd90 c404dda8 00000001 0000004c c437c0c0 bea503f8 00000000
[  149.457521] dd80: bea503c8 00000030 0000004c 00000000 00000000 00000000 00021048 00000000
[  149.458592] dda0: 00000800 00000000 00000000 00000000 bea503f8 00000000 00021050 00000044
[  149.459703] ddc0: 00000024 c404de28 00000001 c073b3f8 c437cec0 c404de28 c401f960 00000000
[  149.460790] dde0: 00000001 c073c1fc 00000000 c074b2e0 00000000 c30bed08 00000001 c074b2e0
[  149.461852] de00: 00000002 c30bed00 c437cec0 00000001 00000001 c126662c c437cd80 00000001
[  149.462407] de20: c437cd80 00000001 c437cec0 00000000 00000000 c0248394 c401f960 c401f960
[  149.462842] de40: c401f960 c401f960 c16ee780 c401f840 c404de60 c02489a8 00000000 00000030
[  149.463289] de60: 0000004c 00000000 00000000 00000000 00021048 00000000 00000800 00000000
[  149.463822] de80: 00000000 00000000 bea503f8 00000000 c405bb40 00000000 f9cf40ab fffffff4
[  149.464278] dea0: 00000000 c401f840 00000000 c404c000 c401f854 c405bb40 c21b3000 00000001
[  149.464708] dec0: 00000071 00000001 ffffffea c0306201 00000001 c30bed00 c405bb40 c405bb40
[  149.465170] dee0: c404dfa0 c0733f80 00000030 c30bed00 c404df24 00000030 c405bb40 c30bed00
[  149.465742] df00: c404df10 c0306201 bea503c8 c0738104 c0306201 bea503c8 00000000 bea503c8
[  149.466167] df20: 00000030 c405bb40 00000003 c16ee690 c404df60 c028d42c 00000006 00001000
[  149.466691] df40: 00000001 c404df44 c404df44 00000000 f9cf40ab c405bb40 00000000 00000000
[  149.467298] df60: 00000002 c0248668 c405bb40 b6fcc000 c404dfa0 c0248668 00000002 00000000
[  149.467844] df80: f9cf40ab bea503f8 00000000 0001059d 00000036 c0100264 c404c000 00000036
[  149.468396] dfa0: 00000000 c0100060 bea503f8 00000000 00000003 c0306201 bea503c8 bea503c8
[  149.468864] dfc0: bea503f8 00000000 0001059d 00000036 00021048 00000000 b6fd0000 00000000
[  149.469355] dfe0: b6ef6510 bea503b4 0001086b b6ef651c 60000010 00000003 00000000 00000000
[  149.470240] [<c04631b0>] (rust_helper_BUG) from [<c0462888>] (rust_begin_unwind+0x4/0x8)
[  149.470959] Code: e92d4800 e1a0b00d e92d4000 e8bd4000 (e7f001f2) 
[  149.471647] ---[ end trace faab23bf7569842d ]---

[wedsonaf]

Thanks Sven!

Could you try it on the C version of binder?

(Either way we should not allow a user space process to affect the kernel this way, but as a data point, it would be good to know if the ping client/server work on the C version of binder; I believe this is the first time they run on a 32-bit arch.)

[TheSven73]

First time I ran the client, I get "illegal instruction"?

root@raspberrypi:/home/pi# ./ping_client /dev/binder 
[1]+  Illegal instruction     ./ping_server /dev/binder
Illegal instruction

Afterwards, I do get some kind of failure:

root@raspberrypi:/home/pi# ./ping_client /dev/binder 
[  125.409426] binder: 331:331 BC_FREE_BUFFER u4040630000000000 no match
[  125.411598] binder: 331:331 unknown command 0
[  125.411964] binder: 331:331 ioctl c0306201 bea2e3e8 returned -22
ioctl: Invalid argument

Maybe I need to switch on selftests in defconfig?

[TheSven73]

When selftest is activated in defconfig, C binder oopses when the server is started:

root@raspberrypi:/home/pi# ./ping_server /dev/binder &
[1] 329
root@raspberrypi:/home/pi# [  112.214879] binder_alloc_selftest: STARTED
[  112.250097] binder_alloc: 329: binder_alloc_buf size 2560 failed, no address space
[  112.251679] binder_alloc: allocated: 2048 (num: 4 largest: 512), free: 2048 (num: 1 largest: 2048)
[  112.252006] binder_alloc_selftest: alloc sizes: [512][512][512][512][2560]
[  112.252621] binder_alloc_selftest: free seq: [0][1][2][3][4]
[  112.253182] 8<--- cut here ---
[  112.253369] Unable to handle kernel paging request at virtual address fffffff8
[  112.253643] pgd = (ptrval)
[  112.253815] [fffffff8] *pgd=2bfde861, *pte=00000000, *ppte=00000000
[  112.254342] Internal error: Oops: 37 [#1] ARM
[  112.254619] Modules linked in:
[  112.254893] CPU: 0 PID: 329 Comm: ping_server Tainted: G        W         5.12.0-rc4+ #3
[  112.255170] Hardware name: BCM2835
[  112.255317] PC is at binder_alloc_free_buf+0x18/0x5c
[  112.255779] LR is at binder_selftest_free_buf+0x3c/0xdc
[  112.255970] pc : [<c0742eec>]    lr : [<c0744ed4>]    psr: 20000013
[  112.256150] sp : c4049a30  ip : c1028500  fp : c4049a38
[  112.256309] r10: 00001200  r9 : c4049c34  r8 : 00001200
[  112.256505] r7 : c4049a74  r6 : c237cf2c  r5 : ffffffe4  r4 : c237cf2c
[  112.256710] r3 : 00000000  r2 : c2198000  r1 : ffffffe4  r0 : c237cf2c
[  112.256968] Flags: nzCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
[  112.257149] Control: 10c53c7d  Table: 04064059  DAC: 00000051
[  112.257362] Process ping_server (pid: 329, stack limit = 0x(ptrval))
[  112.257553] Stack: (0xc4049a30 to 0xc404a000)
[  112.257808] 9a20:                                     c4049c48 fffffffc c4049a60 c0744ed4
[  112.258305] 9a40: c4049a74 c237cf2c c4049c48 c4049a74 00000005 c4049c34 00000004 00001200
[  112.258696] 9a60: c4049aa8 c0744bb8 00001200 c0321970 00000000 c3252d40 c3252c40 c3252a00
[  112.259045] 9a80: c3252c80 ffffffe4 9665fd41 c237cf2c c4049c48 00000005 00000004 c4049c34
[  112.259404] 9aa0: 00000004 00001200 c4049af0 c0744d20 00001200 00000000 00000001 c3252cc0
[  112.259951] 9ac0: 00000000 c1571000 00000000 00000001 9665fd41 c237cf2c c4049c48 00000004
[  112.260545] 9ae0: 00000003 c4049c34 00000003 00001200 c4049b38 c0744d20 00001200 00000000
[  112.261195] 9b00: 00000000 c1710500 c4049b60 c04a3854 c4049b8c c1798000 9665fd41 c237cf2c
[  112.261906] 9b20: c4049c48 00000003 00000002 c4049c34 00000002 00001200 c4049b80 c0744d20
[  112.262669] 9b40: 00001200 c17a3a30 9665fd41 c1168dec c1169698 c02562d0 c1168dec 00000801
[  112.263405] 9b60: 9665fd41 c237cf2c c4049c48 00000002 00000001 c4049c34 00000001 00001200
[  112.264162] 9b80: c4049bc8 c0744d20 00001200 00000000 00000001 00000000 00000801 c1168dec
[  112.264819] 9ba0: 00000000 00002800 9665fd41 c237cf2c c4049c48 00000001 00000000 c4049c34
[  112.265427] 9bc0: 00000000 00001200 c4049c10 c0744d20 00001200 60000013 c4049bf4 00000000
[  112.265971] 9be0: c4049c28 c01581e0 00000000 c4049bf4 9665fd41 fffffffb c4049c48 00000005
[  112.266673] 9c00: 00000005 fffff000 00001200 c237cf2c c4049c80 c0744ab8 00001200 00000000
[  112.267228] 9c20: 00000800 00000200 00000200 00000200 00000200 00000200 00000200 00000200
[  112.267903] 9c40: 00000200 00000a00 00000000 00000001 00000002 00000003 00000004 c0292f58
[  112.268462] 9c60: 9665fd41 00000002 c4049eb8 00000004 00000005 fffff000 00001200 c237cf2c
[  112.269068] 9c80: c4049cf0 c0744b18 0003475f 00000000 0000000a 00000006 00000001 00000000
[  112.269702] 9ca0: 34383739 c02c3231 22921900 c0165cc0 c1010488 00000000 00000192 00000000
[  112.270280] 9cc0: c4049d4c c1004248 c4049d00 c0165cc0 9665fd41 00000000 c4049eb8 00000003
[  112.270843] 9ce0: 00000004 fffff000 00000800 c237cf2c c4049d60 c0744b18 c4049d40 00000000
[  112.271442] 9d00: c4049d78 c0165728 00000000 c4049d60 c1010484 00000400 c4049d50 c101049c
[  112.272028] 9d20: c4049d30 00000000 c4049d80 00000000 00000000 00000192 c1028500 00000000
[  112.272541] 9d40: 9665fd41 00000000 c4049eb8 00000002 00000003 fffff000 00000600 c237cf2c
[  112.273079] 9d60: c4049dd0 c0744b18 c1004248 c11db340 c1010484 c11db348 c4049da0 c01654f8
[  112.273700] 9d80: 00000192 00000000 60000093 9665fd41 c4049db4 00000000 00000000 c0162600
[  112.274339] 9da0: c4049e38 c0162600 00000000 00000000 9665fd41 00000000 c4049eb8 00000001
[  112.274872] 9dc0: 00000002 fffff000 00000400 c237cf2c c4049e40 c0744b18 00000000 00000000
[  112.275434] 9de0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[  112.276043] 9e00: 00000000 00000000 00000000 00000000 00000000 00000000 9665fd41 0000001e
[  112.276645] 9e20: 9665fd41 00000000 c4049eb8 00000000 00000001 fffff000 00000200 c237cf2c
[  112.277166] 9e40: c4049eb0 c0744b18 c16ef780 c4057cc0 00000000 c4049eac c0d1e027 c123ec28
[  112.277744] 9e60: 40046207 00000000 40046207 c237ce00 c4049e88 c0162764 c4049eac c4057780
[  112.278301] 9e80: c0d1e027 c1004248 c4049ea4 c09f1b2c 9665fd41 c237cf2c c1004248 c123ec28
[  112.278892] 9ea0: 40046207 00000000 40046207 c237ce00 c4049ee0 c07449b4 00000200 00000400
[  112.279393] 9ec0: 00000600 00000800 00001200 9665fd41 c4044c00 c16ef690 00000000 c237ce00
[  112.279920] 9ee0: c4049f30 c0734974 00000000 c4049f44 9665fd41 00000002 00001000 00000001
[  112.280352] 9f00: c4044c00 c3287c40 c4044c00 fffffffc 9665fd41 00000003 c16ef690 c4049f60
[  112.280934] 9f20: 40046207 00000000 c4044c00 c4044c00 c4049fa0 c028d42c 00000006 00001000
[  112.281449] 9f40: 00000001 c4049f44 c4049f44 00000000 9665fd41 c4044c00 00000000 00000000
[  112.281905] 9f60: 00000002 c0248668 c4044c00 b6f79000 c4049fa0 c0248668 00000002 00000000
[  112.282357] 9f80: 9665fd41 00000000 000108e9 0001050d 00000036 c0100264 c4048000 00000036
[  112.282979] 9fa0: 00000000 c0100060 00000000 000108e9 00000003 40046207 00000000 b6f79000
[  112.283553] 9fc0: 00000000 000108e9 0001050d 00000036 00000000 00000000 b6f7d000 00000000
[  112.284028] 9fe0: b6ea3510 bece13b4 00010781 b6ea351c 60000010 00000003 00000000 00000000
[  112.284890] [<c0742eec>] (binder_alloc_free_buf) from [<c0744ed4>] (binder_selftest_free_buf+0x3c/0xdc)
[  112.285501] [<c0744ed4>] (binder_selftest_free_buf) from [<c0744bb8>] (binder_selftest_free_seq+0x6c/0x228)
[  112.285852] [<c0744bb8>] (binder_selftest_free_seq) from [<c0744d20>] (binder_selftest_free_seq+0x1d4/0x228)
[  112.286182] [<c0744d20>] (binder_selftest_free_seq) from [<c0744d20>] (binder_selftest_free_seq+0x1d4/0x228)
[  112.286523] [<c0744d20>] (binder_selftest_free_seq) from [<c0744d20>] (binder_selftest_free_seq+0x1d4/0x228)
[  112.286870] [<c0744d20>] (binder_selftest_free_seq) from [<c0744d20>] (binder_selftest_free_seq+0x1d4/0x228)
[  112.287216] [<c0744d20>] (binder_selftest_free_seq) from [<c0744d20>] (binder_selftest_free_seq+0x1d4/0x228)
[  112.287530] [<c0744d20>] (binder_selftest_free_seq) from [<c0744ab8>] (binder_selftest_alloc_offset+0xb8/0x14c)
[  112.287893] [<c0744ab8>] (binder_selftest_alloc_offset) from [<c0744b18>] (binder_selftest_alloc_offset+0x118/0x14c)
[  112.288300] [<c0744b18>] (binder_selftest_alloc_offset) from [<c0744b18>] (binder_selftest_alloc_offset+0x118/0x14c)
[  112.288774] [<c0744b18>] (binder_selftest_alloc_offset) from [<c0744b18>] (binder_selftest_alloc_offset+0x118/0x14c)
[  112.289190] [<c0744b18>] (binder_selftest_alloc_offset) from [<c0744b18>] (binder_selftest_alloc_offset+0x118/0x14c)
[  112.289685] [<c0744b18>] (binder_selftest_alloc_offset) from [<c0744b18>] (binder_selftest_alloc_offset+0x118/0x14c)
[  112.290284] [<c0744b18>] (binder_selftest_alloc_offset) from [<c07449b4>] (binder_selftest_alloc+0x8c/0xd8)
[  112.290716] [<c07449b4>] (binder_selftest_alloc) from [<c0734974>] (binder_ioctl+0x38/0x864)
[  112.291053] [<c0734974>] (binder_ioctl) from [<c028d42c>] (sys_ioctl+0x908/0xa50)
[  112.291488] [<c028d42c>] (sys_ioctl) from [<c0100060>] (ret_fast_syscall+0x0/0x58)
[  112.291873] Exception stack(0xc4049fa8 to 0xc4049ff0)
[  112.292289] 9fa0:                   00000000 000108e9 00000003 40046207 00000000 b6f79000
[  112.292848] 9fc0: 00000000 000108e9 0001050d 00000036 00000000 00000000 b6f7d000 00000000
[  112.293246] 9fe0: b6ea3510 bece13b4 00010781 b6ea351c
[  112.293766] Code: e1a05001 e1a04000 e92d4000 e8bd4000 (e5d50014) 
[  112.294795] ---[ end trace 86083b9ff3cb8f93 ]---

[TheSven73]

I apologize for running this on 32-bit architecture (which is not that important in the grand scheme of things). However, the real-world devices I have and am most familiar with, are 32-bit arm.

[ojeda]

Finding and reporting bugs is never something to apologize for! :)

[TheSven73]

Yes, but I think this BUG is probably a distraction from getting this benchmark to run.
I think the benchmark is much more important than a 32-bit binder bug.

(edited: I am now going to try on a 64-bit arm Raspberry Pi 3)

[TheSven73]

I tried on a 64-bit arm Raspberry Pi 3:

pi@raspberrypi:~$ lscpu
Architecture:        aarch64
Byte Order:          Little Endian
CPU(s):              4
On-line CPU(s) list: 0-3
Thread(s) per core:  1
Core(s) per socket:  4
Socket(s):           1
NUMA node(s):        1
Vendor ID:           ARM
Model:               4
Model name:          Cortex-A53
Stepping:            r0p4
BogoMIPS:            125.00
NUMA node0 CPU(s):   0-3
Flags:               fp asimd evtstrm aes pmull sha1 sha2 crc32 cpuid
pi@raspberrypi:~$ ./ping_server /dev/binder &
pi@raspberrypi:~$ ./ping_client /dev/binder 
ioctl: Invalid argument

I get the same result with /dev/rust_binder. Not sure what's going on.

[TheSven73]

If it helps, here are the results of the C binder selftest on arm64:

[   87.339991] binder_alloc_selftest: STARTED
[   87.362712] binder_alloc: 386: binder_alloc_buf size 2560 failed, no address space
[   87.362796] binder_alloc: allocated: 2048 (num: 4 largest: 512), free: 2048 (num: 1 largest: 2048)
[   87.362825] binder_alloc_selftest: alloc sizes: [512][512][512][512][2560]
[   87.363866] binder_alloc_selftest: free seq: [0][1][2][3][4]
[   87.364361] Unable to handle kernel NULL pointer dereference at virtual address 000000000000000c
[   87.365204] Mem abort info:
[   87.365275]   ESR = 0x96000007
[   87.365373]   EC = 0x25: DABT (current EL), IL = 32 bits
[   87.365416]   SET = 0, FnV = 0
[   87.365443]   EA = 0, S1PTW = 0
[   87.365481] Data abort info:
[   87.365509]   ISV = 0, ISS = 0x00000007
[   87.365552]   CM = 0, WnR = 0
[   87.365636] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000005d9a000
[   87.365698] [000000000000000c] pgd=00000000057cb003, p4d=00000000057cb003, pud=0000000005da9003, pmd=0000000005dac003, pte=0000000000000000
[   87.365991] Internal error: Oops: 96000007 [#1] PREEMPT SMP
[   87.366179] Modules linked in:
[   87.366406] CPU: 1 PID: 386 Comm: ping_server Tainted: G        W         5.12.0-rc4-698413-g76001a4dd2a8-dirty #3
[   87.366581] Hardware name: Raspberry Pi 3 Model A+ (DT)
[   87.366742] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
[   87.366813] pc : binder_alloc_free_buf+0x18/0xf8
[   87.367194] lr : binder_selftest_free_buf+0x80/0x12c
[   87.367332] sp : ffff800011f734d0
[   87.367383] x29: ffff800011f734d0 x28: ffff0000056b0e00 
[   87.367614] x27: 0000000000000000 x26: 0000000000000004 
[   87.367772] x25: 0000000000000004 x24: 0000000000000004 
[   87.367860] x23: ffff800011f73580 x22: 0000000000001200 
[   87.367920] x21: ffff000005d4dd78 x20: ffff800011f738f8 
[   87.367987] x19: ffff800011f73920 x18: ffffffffffffffff 
[   87.368113] x17: 0000000000000000 x16: 0000000000000000 
[   87.368190] x15: 0000000000000004 x14: 0000000000000fff 
[   87.368252] x13: fffffc0000000000 x12: 0000000000000000 
[   87.368303] x11: ffff000005d4ddc0 x10: 0000000000000000 
[   87.368370] x9 : 0000000000000000 x8 : 0000000000000004 
[   87.368439] x7 : 3a71657320656572 x6 : ffff800011ba3f29 
[   87.368513] x5 : 0000000000000001 x4 : ffff000037dbfea0 
[   87.368600] x3 : 0000000000581401 x2 : 0000000000000001 
[   87.368679] x1 : ffffffffffffffe4 x0 : ffff000005d4dd78 
[   87.368846] Call trace:
[   87.368999]  binder_alloc_free_buf+0x18/0xf8
[   87.369114]  binder_selftest_free_buf+0x80/0x12c
[   87.369191]  binder_selftest_free_seq+0x70/0x498
[   87.369276]  binder_selftest_free_seq+0x3cc/0x498
[   87.369317]  binder_selftest_free_seq+0x370/0x498
[   87.369356]  binder_selftest_free_seq+0x314/0x498
[   87.369409]  binder_selftest_free_seq+0x2b8/0x498
[   87.369450]  binder_selftest_free_seq+0x25c/0x498
[   87.369505]  binder_selftest_alloc_offset+0xa0/0x18c
[   87.369557]  binder_selftest_alloc_offset+0x120/0x18c
[   87.369608]  binder_selftest_alloc_offset+0xec/0x18c
[   87.369663]  binder_selftest_alloc_offset+0xec/0x18c
[   87.369712]  binder_selftest_alloc_offset+0xec/0x18c
[   87.369775]  binder_selftest_alloc_offset+0xec/0x18c
[   87.369830]  binder_selftest_alloc+0x9c/0xd8
[   87.369900]  binder_ioctl+0x48/0xbd8
[   87.369952]  compat_ptr_ioctl+0x20/0x34
[   87.369992]  __arm64_compat_sys_ioctl+0x104/0x158
[   87.370047]  el0_svc_common+0x90/0x110
[   87.370135]  do_el0_svc_compat+0x1c/0x40
[   87.370195]  el0_svc_compat+0x28/0x88
[   87.370232]  el0_sync_compat_handler+0x78/0xb4
[   87.370278]  el0_sync_compat+0x174/0x180
[   87.370553] Code: a9015ff8 a90257f6 a9034ff4 910003fd (b9402828) 
[   87.371002] ---[ end trace 02e55523d13b1f45 ]---

[nbdd0121]

Cause of BUG:

panicked at 'attempt to subtract with overflow', drivers/android/process.rs:548:22

EDIT: replacing the subtraction with wrapping_sub does not work.

[wedsonaf]

If it helps, here are the results of the C binder selftest on arm64:

C binder has same self tests that run in the kernel and they seem to be failing. I think it's better to disable them for now.

[wedsonaf]

I tried on a 64-bit arm Raspberry Pi 3:

pi@raspberrypi:~$ lscpu
Architecture:        aarch64
Byte Order:          Little Endian
CPU(s):              4
On-line CPU(s) list: 0-3
Thread(s) per core:  1
Core(s) per socket:  4
Socket(s):           1
NUMA node(s):        1
Vendor ID:           ARM
Model:               4
Model name:          Cortex-A53
Stepping:            r0p4
BogoMIPS:            125.00
NUMA node0 CPU(s):   0-3
Flags:               fp asimd evtstrm aes pmull sha1 sha2 crc32 cpuid
pi@raspberrypi:~$ ./ping_server /dev/binder &
pi@raspberrypi:~$ ./ping_client /dev/binder 
ioctl: Invalid argument

I get the same result with /dev/rust_binder. Not sure what's going on.

I have seen this before, in my case it had to do with different alignment when compiling structs in kernel and user spaces (due to different compiler settings/configs). Since the size of structs is encoded as part of the ioctl number, it would result in ioctl numbers that are unknown to the kernel.

Let me take a look.

[TheSven73]

I can confirm that nothing changes on arm or arm64 after applying #366 :(