Hi Russell, Russell King - ARM Linux admin <linux@xxxxxxxxxxxxxxx> wrote on Tue, 22 Oct 2019 09:26:43 +0100: > On Fri, Oct 18, 2019 at 04:36:43PM +0200, Miquel Raynal wrote: > > Any write with either dd or flashcp to a device driven by the > > spear_smi.c driver will pass through the spear_smi_cpy_toio() > > function. This function will get called for chunks of up to 256 bytes. > > If the amount of data is smaller, we may have a problem if the data > > length is not 4-byte aligned. In this situation, the kernel panics > > during the memcpy: > > > > # dd if=/dev/urandom bs=1001 count=1 of=/dev/mtd6 > > spear_smi_cpy_toio [620] dest c9070000, src c7be8800, len 256 > > spear_smi_cpy_toio [620] dest c9070100, src c7be8900, len 256 > > spear_smi_cpy_toio [620] dest c9070200, src c7be8a00, len 256 > > spear_smi_cpy_toio [620] dest c9070300, src c7be8b00, len 233 > > Unhandled fault: external abort on non-linefetch (0x808) at 0xc90703e8 > > [...] > > PC is at memcpy+0xcc/0x330 > > I need the full oops if you want me to comment on this. FYI, I ran the dd command within a for loop, incrementing the block size (bs) by one byte, if failed with bs=6. Disabling WB_MODE (burst mode) does not change anything. Adding a wmb() right after the memcpy_toio() prevents the fault. Here is the full trace when writing 1001 bytes: # dd if=/dev/urandom bs=1001 count=1 of=/dev/mtd6 Unhandled fault: external abort on non-linefetch (0x808) at 0xc90703e8 pgd = c7be8000 [c90703e8] *pgd=f8000452(bad) Internal error: : 808 [#1] ARM Modules linked in: CPU: 0 PID: 660 Comm: dd Not tainted 4.14.0-00045-gf5d08192704f-dirty #6 Hardware name: ST SPEAr600 (Flattened Device Tree) task: c7a05080 task.stack: c7bd2000 PC is at memcpy+0xcc/0x330 LR is at 0x13f0ec28 pc : [<c044344c>] lr : [<13f0ec28>] psr: 80000013 sp : c7bd3e44 ip : 00000018 fp : 000003e9 r10: 00000000 r9 : c7a9959c r8 : c7bd3eac r7 : c7a99590 r6 : c7afb438 r5 : 00000300 r4 : 5171436c r3 : 00000058 r2 : 80000000 r1 : c7be4be9 r0 : c90703e8 Flags: Nzcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none Control: 0005317f Table: 07be8000 DAC: 00000051 Process dd (pid: 660, stack limit = 0xc7bd2190) Stack: (0xc7bd3e44 to 0xc7bd4000) 3e40: c9070300 000000e9 c0290d14 c9070300 c7be4b00 0001046f c9070000 3e60: c7afb418 00000000 c7bd3e98 000003e9 c7bd3f88 000003e9 00000000 000c0008 3e80: 00000051 c7bd2000 c7be4800 c028e57c 000003e9 c7bd3eac c7be4800 00000000 3ea0: c7bf73c0 c7addc00 000003e9 00000300 00000000 00000000 00000000 00000000 3ec0: 00000000 00000000 00000000 00000000 00000000 000003e9 c028e4bc c7962a80 3ee0: c7bd3f88 00000000 c7bd2000 00000000 000bf990 c00bdb0c 000bf990 c00bd878 3f00: 00000000 00000000 00000000 c7bd3f10 c7a688c0 c009eedc c7becb58 000c0000 3f20: 00000003 c7962460 c7962484 00000000 00000000 c045c2f8 00000003 c00d9e58 3f40: 000003e9 000c0008 c7962a80 c7bd3f88 00000000 c7bd2000 00000000 c00bddb4 3f60: 000bf990 c00bda6c 00000000 c7962a80 c7962a80 000c0008 000003e9 c000a804 3f80: c7bd2000 c00bdfa4 00000000 00000000 00000000 000bfd94 00000001 000c0008 3fa0: 00000004 c000a640 000bfd94 00000001 00000001 000c0008 000003e9 be8e8f53 3fc0: 000bfd94 00000001 000c0008 00000004 000c0008 000c0008 000003e9 000bf990 3fe0: 00000000 be8e8ba4 0000ea3c b6eba7ec 60000010 00000001 00000000 00000000 [<c044344c>] (memcpy) from [<c0290d14>] (spear_mtd_write+0x240/0x294) [<c0290d14>] (spear_mtd_write) from [<c028e57c>] (mtdchar_write+0xc0/0x230) [<c028e57c>] (mtdchar_write) from [<c00bdb0c>] (__vfs_write+0x1c/0x128) [<c00bdb0c>] (__vfs_write) from [<c00bddb4>] (vfs_write+0xa0/0x168) [<c00bddb4>] (vfs_write) from [<c00bdfa4>] (SyS_write+0x3c/0x90) [<c00bdfa4>] (SyS_write) from [<c000a640>] (ret_fast_syscall+0x0/0x44) Code: e1b02f82 14d13001 24d14001 24d1c001 (14c03001) ---[ end trace f9a736cc2841cf14 ]--- Segmentation fault Thanks, Miquèl
