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Message-ID: <20230411-turbulent-caddie-de82cf1a0f8f@spud>
Date: Tue, 11 Apr 2023 19:30:00 +0100
From: Conor Dooley <conor@...nel.org>
To: Roman Gushchin <roman.gushchin@...ux.dev>
Cc: netdev@...r.kernel.org, Jakub Kicinski <kuba@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
linux-kernel@...r.kernel.org, Rafal Ozieblo <rafalo@...ence.com>,
Lars-Peter Clausen <lars@...afoo.de>,
nicolas.ferre@...rochip.com, claudiu.beznea@...rochip.com
Subject: Re: [PATCH net] net: macb: fix a memory corruption in extended
buffer descriptor mode
On Tue, Apr 11, 2023 at 11:20:34AM -0700, Roman Gushchin wrote:
> Friendly ping.
Nicolas and Claudiu look after the macb stuff, it's a good idea to CC
the people that get_maintainer.pl says are supporters of the code!
> Also cc'ing Dave.
+CC Nicolas & Claudiu ;)
> Thanks!
>
> On Fri, Apr 07, 2023 at 10:24:02AM -0700, Roman Gushchin wrote:
> > For quite some time we were chasing a bug which looked like a sudden
> > permanent failure of networking and mmc on some of our devices.
> > The bug was very sensitive to any software changes and even more to
> > any kernel debug options.
> >
> > Finally we got a setup where the problem was reproducible with
> > CONFIG_DMA_API_DEBUG=y and it revealed the issue with the rx dma:
> >
> > [ 16.992082] ------------[ cut here ]------------
> > [ 16.996779] DMA-API: macb ff0b0000.ethernet: device driver tries to free DMA memory it has not allocated [device address=0x0000000875e3e244] [size=1536 bytes]
> > [ 17.011049] WARNING: CPU: 0 PID: 85 at kernel/dma/debug.c:1011 check_unmap+0x6a0/0x900
> > [ 17.018977] Modules linked in: xxxxx
> > [ 17.038823] CPU: 0 PID: 85 Comm: irq/55-8000f000 Not tainted 5.4.0 #28
> > [ 17.045345] Hardware name: xxxxx
> > [ 17.049528] pstate: 60000005 (nZCv daif -PAN -UAO)
> > [ 17.054322] pc : check_unmap+0x6a0/0x900
> > [ 17.058243] lr : check_unmap+0x6a0/0x900
> > [ 17.062163] sp : ffffffc010003c40
> > [ 17.065470] x29: ffffffc010003c40 x28: 000000004000c03c
> > [ 17.070783] x27: ffffffc010da7048 x26: ffffff8878e38800
> > [ 17.076095] x25: ffffff8879d22810 x24: ffffffc010003cc8
> > [ 17.081407] x23: 0000000000000000 x22: ffffffc010a08750
> > [ 17.086719] x21: ffffff8878e3c7c0 x20: ffffffc010acb000
> > [ 17.092032] x19: 0000000875e3e244 x18: 0000000000000010
> > [ 17.097343] x17: 0000000000000000 x16: 0000000000000000
> > [ 17.102647] x15: ffffff8879e4a988 x14: 0720072007200720
> > [ 17.107959] x13: 0720072007200720 x12: 0720072007200720
> > [ 17.113261] x11: 0720072007200720 x10: 0720072007200720
> > [ 17.118565] x9 : 0720072007200720 x8 : 000000000000022d
> > [ 17.123869] x7 : 0000000000000015 x6 : 0000000000000098
> > [ 17.129173] x5 : 0000000000000000 x4 : 0000000000000000
> > [ 17.134475] x3 : 00000000ffffffff x2 : ffffffc010a1d370
> > [ 17.139778] x1 : b420c9d75d27bb00 x0 : 0000000000000000
> > [ 17.145082] Call trace:
> > [ 17.147524] check_unmap+0x6a0/0x900
> > [ 17.151091] debug_dma_unmap_page+0x88/0x90
> > [ 17.155266] gem_rx+0x114/0x2f0
> > [ 17.158396] macb_poll+0x58/0x100
> > [ 17.161705] net_rx_action+0x118/0x400
> > [ 17.165445] __do_softirq+0x138/0x36c
> > [ 17.169100] irq_exit+0x98/0xc0
> > [ 17.172234] __handle_domain_irq+0x64/0xc0
> > [ 17.176320] gic_handle_irq+0x5c/0xc0
> > [ 17.179974] el1_irq+0xb8/0x140
> > [ 17.183109] xiic_process+0x5c/0xe30
> > [ 17.186677] irq_thread_fn+0x28/0x90
> > [ 17.190244] irq_thread+0x208/0x2a0
> > [ 17.193724] kthread+0x130/0x140
> > [ 17.196945] ret_from_fork+0x10/0x20
> > [ 17.200510] ---[ end trace 7240980785f81d6f ]---
> >
> > [ 237.021490] ------------[ cut here ]------------
> > [ 237.026129] DMA-API: exceeded 7 overlapping mappings of cacheline 0x0000000021d79e7b
> > [ 237.033886] WARNING: CPU: 0 PID: 0 at kernel/dma/debug.c:499 add_dma_entry+0x214/0x240
> > [ 237.041802] Modules linked in: xxxxx
> > [ 237.061637] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G W 5.4.0 #28
> > [ 237.068941] Hardware name: xxxxx
> > [ 237.073116] pstate: 80000085 (Nzcv daIf -PAN -UAO)
> > [ 237.077900] pc : add_dma_entry+0x214/0x240
> > [ 237.081986] lr : add_dma_entry+0x214/0x240
> > [ 237.086072] sp : ffffffc010003c30
> > [ 237.089379] x29: ffffffc010003c30 x28: ffffff8878a0be00
> > [ 237.094683] x27: 0000000000000180 x26: ffffff8878e387c0
> > [ 237.099987] x25: 0000000000000002 x24: 0000000000000000
> > [ 237.105290] x23: 000000000000003b x22: ffffffc010a0fa00
> > [ 237.110594] x21: 0000000021d79e7b x20: ffffffc010abe600
> > [ 237.115897] x19: 00000000ffffffef x18: 0000000000000010
> > [ 237.121201] x17: 0000000000000000 x16: 0000000000000000
> > [ 237.126504] x15: ffffffc010a0fdc8 x14: 0720072007200720
> > [ 237.131807] x13: 0720072007200720 x12: 0720072007200720
> > [ 237.137111] x11: 0720072007200720 x10: 0720072007200720
> > [ 237.142415] x9 : 0720072007200720 x8 : 0000000000000259
> > [ 237.147718] x7 : 0000000000000001 x6 : 0000000000000000
> > [ 237.153022] x5 : ffffffc010003a20 x4 : 0000000000000001
> > [ 237.158325] x3 : 0000000000000006 x2 : 0000000000000007
> > [ 237.163628] x1 : 8ac721b3a7dc1c00 x0 : 0000000000000000
> > [ 237.168932] Call trace:
> > [ 237.171373] add_dma_entry+0x214/0x240
> > [ 237.175115] debug_dma_map_page+0xf8/0x120
> > [ 237.179203] gem_rx_refill+0x190/0x280
> > [ 237.182942] gem_rx+0x224/0x2f0
> > [ 237.186075] macb_poll+0x58/0x100
> > [ 237.189384] net_rx_action+0x118/0x400
> > [ 237.193125] __do_softirq+0x138/0x36c
> > [ 237.196780] irq_exit+0x98/0xc0
> > [ 237.199914] __handle_domain_irq+0x64/0xc0
> > [ 237.204000] gic_handle_irq+0x5c/0xc0
> > [ 237.207654] el1_irq+0xb8/0x140
> > [ 237.210789] arch_cpu_idle+0x40/0x200
> > [ 237.214444] default_idle_call+0x18/0x30
> > [ 237.218359] do_idle+0x200/0x280
> > [ 237.221578] cpu_startup_entry+0x20/0x30
> > [ 237.225493] rest_init+0xe4/0xf0
> > [ 237.228713] arch_call_rest_init+0xc/0x14
> > [ 237.232714] start_kernel+0x47c/0x4a8
> > [ 237.236367] ---[ end trace 7240980785f81d70 ]---
> >
> > Lars was fast to find an explanation: according to the datasheet
> > bit 2 of the rx buffer descriptor entry has a different meaning in the
> > extended mode:
> > Address [2] of beginning of buffer, or
> > in extended buffer descriptor mode (DMA configuration register [28] = 1),
> > indicates a valid timestamp in the buffer descriptor entry.
> >
> > The macb driver didn't mask this bit while getting an address and it
> > eventually caused a memory corruption and a dma failure.
> >
> > The problem is resolved by extending the MACB_RX_WADDR_SIZE
> > in the extended mode.
> >
> > Fixes: 7b4296148066 ("net: macb: Add support for PTP timestamps in DMA descriptors")
> > Signed-off-by: Roman Gushchin <roman.gushchin@...ux.dev>
> > Co-developed-by: Lars-Peter Clausen <lars@...afoo.de>
> > Signed-off-by: Lars-Peter Clausen <lars@...afoo.de>
> > ---
> > drivers/net/ethernet/cadence/macb.h | 5 +++++
> > 1 file changed, 5 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
> > index c1fc91c97cee..1b330f7cfc09 100644
> > --- a/drivers/net/ethernet/cadence/macb.h
> > +++ b/drivers/net/ethernet/cadence/macb.h
> > @@ -826,8 +826,13 @@ struct macb_dma_desc_ptp {
> > #define MACB_RX_USED_SIZE 1
> > #define MACB_RX_WRAP_OFFSET 1
> > #define MACB_RX_WRAP_SIZE 1
> > +#ifdef MACB_EXT_DESC
> > +#define MACB_RX_WADDR_OFFSET 3
> > +#define MACB_RX_WADDR_SIZE 29
> > +#else
> > #define MACB_RX_WADDR_OFFSET 2
> > #define MACB_RX_WADDR_SIZE 30
> > +#endif
> >
> > #define MACB_RX_FRMLEN_OFFSET 0
> > #define MACB_RX_FRMLEN_SIZE 12
> > --
> > 2.40.0
> >
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