Date:	Fri, 17 Jul 2015 21:12:24 +0800
From:	Peng Fan <van.freenix@...il.com>
To:	Adrian Hunter <adrian.hunter@...el.com>
Cc:	ulf.hansson@...aro.org, tim.kryger@...il.com, b29396@...escale.com,
	haibo.chen@...escale.com, linux-mmc@...r.kernel.org,
	linux-kernel@...r.kernel.org, van.freenix@...il.com
Subject: Re: [PATCH] mmc: host: sdhci check parameters before call
 dma_free_coherent

Hi,

On Mon, Jun 22, 2015 at 10:04:22AM +0300, Adrian Hunter wrote:
> On 22/06/15 06:41, Peng Fan wrote:
> > We should not call dma_free_coherent if host->adma_table is NULL,
> > otherwise may trigger panic.
> > 
> >>From DMA-API.txt:
> > "
> > void
> > dma_free_coherent(struct device *dev, size_t size, void *cpu_addr,
> >                   dma_addr_t dma_handle)
> > 
> > Free a region of consistent memory you previously allocated.  dev,
> > size and dma_handle must all be the same as those passed into
> > dma_alloc_coherent().  cpu_addr must be the virtual address returned by
> > the dma_alloc_coherent().
> > "
> > So we should check cpu_addr, but not directly call dma_free_coherent.
> > 
> > I met this when porting xen, log: "
> > sdhci: Secure Digital Host Controller Interface driver
> > sdhci: Copyright(c) Pierre Ossman
> > sdhci-pltfm: SDHCI platform and OF driver helper
> > Unable to handle kernel NULL pointer dereference at virtual address 00000000
> > pgd = 80004000
> > [00000000] *pgd=00000000
> > Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> > Modules linked in:
> > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.38-02383-g5ccf32b-dirty #22
> > task: 84074000 ti: 84078000 task.ti: 84078000
> > PC is at bitmap_clear+0xc0/0xdc
> > LR is at bitmap_clear+0x54/0xdc
> > pc : [<8029deb8>]    lr : [<8029de4c>]    psr: 20000193
> > sp : 84079d80  ip : 00000001  fp : 00000000
> > r10: 00077fff  r9 : 00000404  r8 : 00000001
> > r7 : 00000001  r6 : 00000001  r5 : 00000000  r4 : ffffffff
> > r3 : 00000001  r2 : 00000001  r1 : 20000193  r0 : 00000015
> > Flags: nzCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
> > Control: 10c53c7d  Table: 8800406a  DAC: 00000015
> > Process swapper/0 (pid: 1, stack limit = 0x84078238)
> > Stack: (0x84079d80 to 0x8407a000)
> > 9d80: 80000113 00000000 87efa000 81109918 00001000 800197f8 84128558 00080008
> > 9da0: 84079dec 000000d0 84bfeac0 84126c10 84126c10 ffffffff 00000404 ffffffff
> > 9dc0: 00000000 00000402 00000000 00000000 84126c10 80310ba8 ffffffff 00000000
> > 9de0: 00000000 00000524 84078000 00000000 00000000 ffffffff ffffffff 84bfeac0
> > 9e00: 84bfe800 8000b407 07eb0000 8116e0f8 00000000 804ee81c ffffffff ffffffff
> > 9e20: 00000000 84126c10 84c92010 84bfeac0 00000000 84126c10 84126c00 84bfeac0
> > 9e40: 84078030 804f08e4 804f03d8 84126c10 fffffdfb 8115401c 8115401c 00000000
> > 9e60: 0000010f 80362330 803622ec 84126c10 811c8098 00000000 8115401c 80360b1c
> > 9e80: 84126c10 8115401c 84126c44 00000000 80de1888 80360d28 00000000 8115401c
> > 9ea0: 80360c9c 8035f10c 8406965c 84123634 8115401c 84c8bf80 8112f3c8 803602bc
> > 9ec0: 80d08314 8115401c 00000006 8115401c 00000006 8116e080 8116e080 8036130c
> > 9ee0: 00000000 80e00f78 00000006 800088dc 8400f900 80c94fe0 840bd480 80735184
> > 9f00: 00000000 8116e080 0000150c 8012d430 00000000 811105b0 60000113 00000001
> > 9f20: 87ffc576 8075ca38 0000010f 8004b0f0 80d66884 00000006 87ffc583 00000006
> > 9f40: 811105a0 80e00f78 00000006 8116e080 8116e080 80da150c 0000010f 80df4154
> > 9f60: 80df4148 80da1c4c 00000006 00000006 80da150c 9355553c 84079f9c 80731338
> > 9f80: 00000000 00000000 80727254 00000000 00000000 00000000 00000000 00000000
> > 9fa0: 00000000 8072725c 00000000 8000ecf8 00000000 00000000 00000000 00000000
> > 9fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > 9fe0: 00000000 00000000 00000000 00000000 00000013 00000000 9355553c 9355553c
> > [<8029deb8>] (bitmap_clear) from [<800197f8>] (__arm_dma_free.isra.18+0xe4/0x228)
> > [<800197f8>] (__arm_dma_free.isra.18) from [<80310ba8>] (xen_swiotlb_free_coherent+0xfc/0x140)
> > [<80310ba8>] (xen_swiotlb_free_coherent) from [<804ee81c>] (sdhci_add_host+0xb34/0xe64)
> > [<804ee81c>] (sdhci_add_host) from [<804f08e4>] (sdhci_esdhc_imx_probe+0x50c/0x808)
> > [<804f08e4>] (sdhci_esdhc_imx_probe) from [<80362330>] (platform_drv_probe+0x44/0xa4)
> > [<80362330>] (platform_drv_probe) from [<80360b1c>] (driver_probe_device+0x120/0x25c)
> > [<80360b1c>] (driver_probe_device) from [<80360d28>] (__driver_attach+0x8c/0x90)
> > [<80360d28>] (__driver_attach) from [<8035f10c>] (bus_for_each_dev+0x60/0x94)
> > [<8035f10c>] (bus_for_each_dev) from [<803602bc>] (bus_add_driver+0x148/0x1f0)
> > [<803602bc>] (bus_add_driver) from [<8036130c>] (driver_register+0x78/0xf8)
> > [<8036130c>] (driver_register) from [<800088dc>] (do_one_initcall+0xf8/0x144)
> > [<800088dc>] (do_one_initcall) from [<80da1c4c>] (kernel_init_freeable+0x138/0x1d8)
> > [<80da1c4c>] (kernel_init_freeable) from [<8072725c>] (kernel_init+0x8/0xf0)
> > [<8072725c>] (kernel_init) from [<8000ecf8>] (ret_from_fork+0x14/0x3c)
> > Code: 10866003 1206601f 10633006 11e02312 (e5953000)
> > ---[ end trace f6f103bb73cc0503 ]---
> > note: swapper/0[1] exited with preempt_count 1
> > Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b"
> > 
> > Because dma_alloc_coherent fail, it returns NULL, then
> > "if (!host->adma_table || !host->align_buffer)" will return true, then
> > dma_free_coherent trigger panic.
> > 
> > After applying this patch, no panic and all work well, kernel log:
> > "
> > sdhci: Secure Digital Host Controller Interface driver
> > sdhci: Copyright(c) Pierre Ossman
> > sdhci-pltfm: SDHCI platform and OF driver helper
> > mmc0: Unable to allocate ADMA buffers. Falling back to standard DMA.
> > mmc0: no vqmmc regulator found
> > mmc0: SDHCI controller on 30b40000.usdhc [30b40000.usdhc] using DMA
> > "
> > 
> > Signed-off-by: Peng Fan <van.freenix@...il.com>
> 
> Acked-by: Adrian Hunter <adrian.hunter@...el.com>
> 
> Looks like the problem started in v3.16 with:
> 
> commit d1e49f77d7c7b75fdc022e1d46c1549bbc91c5b7
> Author: Russell King <rmk+kernel@....linux.org.uk>
> Date:   Fri Apr 25 12:58:34 2014 +0100
> 
>     mmc: sdhci: convert ADMA descriptors to a coherent allocation
> 

Will this patch be merged? Since more than 3 weeks passed, I did not see any further comments about this patch.

> 
> 
> > ---
> >  drivers/mmc/host/sdhci.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index 706bb60..52e2327 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -2978,8 +2978,11 @@ int sdhci_add_host(struct sdhci_host *host)
> >  						      GFP_KERNEL);
> >  		host->align_buffer = kmalloc(host->align_buffer_sz, GFP_KERNEL);
> >  		if (!host->adma_table || !host->align_buffer) {
> > -			dma_free_coherent(mmc_dev(mmc), host->adma_table_sz,
> > -					  host->adma_table, host->adma_addr);
> > +			if (host->adma_table)
> > +				dma_free_coherent(mmc_dev(mmc),
> > +						  host->adma_table_sz,
> > +						  host->adma_table,
> > +						  host->adma_addr);
> >  			kfree(host->align_buffer);
> >  			pr_warn("%s: Unable to allocate ADMA buffers - falling back to standard DMA\n",
> >  				mmc_hostname(mmc));
> > 
> 

Thanks,
Peng
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