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Message-ID: <5409C730.3020202@linaro.org>
Date: Fri, 05 Sep 2014 16:22:40 +0200
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Gaël PORTAY <gael.portay@...il.com>,
Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-pwm@...r.kernel.org, Nicolas Ferre <nicolas.ferre@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
Thierry Reding <thierry.reding@...il.com>,
Boris Brezillon <boris.brezillon@...e-electrons.com>,
Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
Subject: Re: [PATCHv3 3/4] ARM: at91/tclib: mask interruptions at shutdown
and probe
On 09/05/2014 04:14 PM, Gaël PORTAY wrote:
> Shutdown properly the timer counter block by masking interruptions. Otherwise,
> a segmentation may happen when kexec-ing a new kernel (see backtrace below).
> An interruption may happen before the handler is set, leading to a kernel
> segmentation fault.
>
> Furthermore, we make sure the interruptions are masked when the driver is
> initialized. This will prevent freshly kexec-ed kernel from crashing when
> launched from a kernel which does not properly mask interruptions at shutdown.
>
> The backtrace below happened after kexec-ing a new kernel, from a kernel
> that did not shut down properly leaving interruptions unmasked.
>
> Unable to handle kernel NULL pointer dereference at virtual address 00000000
> pgd = c0004000
> [00000000] *pgd=00000000
> Internal error: Oops: 80000005 [#1] ARM
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper Not tainted 3.16.0+ #144
> task: c1828aa0 ti: c182a000 task.ti: c182a000
> PC is at 0x0
> LR is at ch2_irq+0x28/0x30
> pc : [<00000000>] lr : [<c01db904>] psr: 000000d3
> sp : c182bd38 ip : c182bd48 fp : c182bd44
> r10: c0373390 r9 : c1825b00 r8 : 60000053
> r7 : 00000000 r6 : 00000000 r5 : 00000013 r4 : c036e800
> r3 : 00000000 r2 : 00002004 r1 : c036e760 r0 : c036e760
> Flags: nzcv IRQs off FIQs off Mode SVC_32 ISA ARM Segment kernel
> Control: 0005317f Table: 20004000 DAC: 00000017
> Process swapper (pid: 1, stack limit = 0xc182a1c0)
> Stack: (0xc182bd38 to 0xc182c000)
> bd20: c182bd7c c182bd48
> bd40: c0045430 c01db8ec 00000000 c18c6f40 c182bd74 c1825b00 c035cec4 00000000
> bd60: c182be2c 60000053 c1825b34 00000000 c182bd94 c182bd80 c0045570 c0045408
> bd80: 00000000 c1825b00 c182bdac c182bd98 c0047f34 c0045550 00000013 c036619c
> bda0: c182bdc4 c182bdb0 c0044da4 c0047e98 0000007f 00000013 c182bde4 c182bdc8
> bdc0: c0009e34 c0044d8c fefff000 c0046728 60000053 ffffffff c182bdf4 c182bde8
> bde0: c00086a8 c0009ddc c182be74 c182bdf8 c000cb80 c0008674 00000000 00000013
> be00: 00000000 00014200 c1825b00 c036e800 00000013 c035ed98 60000053 c1825b34
> be20: 00000000 c182be74 c182be20 c182be40 c0047994 c0046728 60000053 ffffffff
> be40: 00000013 c036e800 c182be64 c1825b00 00000013 c036e800 c035ed98 c03874bc
> be60: 00000004 c036e700 c182be94 c182be78 c004689c c0046398 c036e760 c18c6080
> be80: 00000000 c035ed10 c182bedc c182be98 c0348b08 c004684c 0000000c c034dac8
> bea0: 004c4b3f c028c338 c036e760 00000013 c014ecc8 c18e67e0 c035b9c0 c0348884
> bec0: c035b9c0 c182a020 00000000 00000000 c182bf54 c182bee0 c00089fc c0348894
> bee0: c00da51c c1ffcc78 c182bf0c c182bef8 c002d100 c002d09c c1ffcc78 00000000
> bf00: c182bf54 c182bf10 c002d308 c0336570 c182bf3c c0334e44 00000003 00000003
> bf20: 00000030 c0334b44 c0044d74 00000003 00000003 c034dac8 c0350a94 c0373440
> bf40: c0373440 00000030 c182bf94 c182bf58 c0336d24 c000890c 00000003 00000003
> bf60: c0336560 c182bf64 c182bf64 6e616e0d 00000000 c0272fc8 00000000 00000000
> bf80: 00000000 00000000 c182bfac c182bf98 c0272fd8 c0336bd8 c182a000 00000000
> bfa0: 00000000 c182bfb0 c00095d0 c0272fd8 00000000 00000000 00000000 00000000
> bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 374d27cd 33cc33e4
> Backtrace:
> [<c01db8dc>] (ch2_irq) from [<c0045430>] (handle_irq_event_percpu+0x38/0x148)
> [<c00453f8>] (handle_irq_event_percpu) from [<c0045570>] (handle_irq_event+0x30/0x40)
> r10:00000000 r9:c1825b34 r8:60000053 r7:c182be2c r6:00000000 r5:c035cec4
> r4:c1825b00
> [<c0045540>] (handle_irq_event) from [<c0047f34>] (handle_fasteoi_irq+0xac/0x11c)
> r4:c1825b00 r3:00000000
> [<c0047e88>] (handle_fasteoi_irq) from [<c0044da4>] (generic_handle_irq+0x28/0x38)
> r5:c036619c r4:00000013
> [<c0044d7c>] (generic_handle_irq) from [<c0009e34>] (handle_IRQ+0x68/0x88)
> r4:00000013 r3:0000007f
> [<c0009dcc>] (handle_IRQ) from [<c00086a8>] (at91_aic_handle_irq+0x44/0x4c)
> r6:ffffffff r5:60000053 r4:c0046728 r3:fefff000
> [<c0008664>] (at91_aic_handle_irq) from [<c000cb80>] (__irq_svc+0x40/0x4c)
> Exception stack(0xc182bdf8 to 0xc182be40)
> bde0: 00000000 00000013
> be00: 00000000 00014200 c1825b00 c036e800 00000013 c035ed98 60000053 c1825b34
> be20: 00000000 c182be74 c182be20 c182be40 c0047994 c0046728 60000053 ffffffff
> [<c0046388>] (__setup_irq) from [<c004689c>] (setup_irq+0x60/0x8c)
> r10:c036e700 r9:00000004 r8:c03874bc r7:c035ed98 r6:c036e800 r5:00000013
> r4:c1825b00
> [<c004683c>] (setup_irq) from [<c0348b08>] (tcb_clksrc_init+0x284/0x31c)
> r6:c035ed10 r5:00000000 r4:c18c6080 r3:c036e760
> [<c0348884>] (tcb_clksrc_init) from [<c00089fc>] (do_one_initcall+0x100/0x1b4)
> r10:00000000 r9:00000000 r8:c182a020 r7:c035b9c0 r6:c0348884 r5:c035b9c0
> r4:c18e67e0
> [<c00088fc>] (do_one_initcall) from [<c0336d24>] (kernel_init_freeable+0x15c/0x224)
> r9:00000030 r8:c0373440 r7:c0373440 r6:c0350a94 r5:c034dac8 r4:00000003
> [<c0336bc8>] (kernel_init_freeable) from [<c0272fd8>] (kernel_init+0x10/0xec)
> r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:c0272fc8 r4:00000000
> [<c0272fc8>] (kernel_init) from [<c00095d0>] (ret_from_fork+0x14/0x24)
> r4:00000000 r3:c182a000
> Code: bad PC value
> ---[ end trace 5b30f0017e282e47 ]---
> Kernel panic - not syncing: Fatal exception in interrupt
>
> Signed-off-by: Gaël PORTAY <gael.portay@...il.com>
> Signed-off-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>
+ a nit below
> ---
> drivers/misc/atmel_tclib.c | 16 ++++++++++++++++
> include/linux/atmel_tc.h | 5 +++++
> 2 files changed, 21 insertions(+)
>
> diff --git a/drivers/misc/atmel_tclib.c b/drivers/misc/atmel_tclib.c
> index d505d1e..cc42f39 100644
> --- a/drivers/misc/atmel_tclib.c
> +++ b/drivers/misc/atmel_tclib.c
> @@ -109,6 +109,7 @@ static int __init tc_probe(struct platform_device *pdev)
> struct clk *clk;
> int irq;
> struct resource *r;
> + unsigned int i;
>
> irq = platform_get_irq(pdev, 0);
> if (irq < 0)
> @@ -157,18 +158,33 @@ static int __init tc_probe(struct platform_device *pdev)
> if (tc->irq[2] < 0)
> tc->irq[2] = irq;
>
> + for (i = 0; i < 3; i++)
> + writel(ATMEL_TC_ALL_IRQ, tc->regs + ATMEL_TC_REG(i, IDR));
> +
> spin_lock(&tc_list_lock);
> list_add_tail(&tc->node, &tc_list);
> spin_unlock(&tc_list_lock);
>
> + platform_set_drvdata(pdev, tc);
> +
> return 0;
> }
>
> +static void tc_shutdown (struct platform_device *pdev)
Typo : extra space between the function name and the parenthesis.
> +{
> + int i;
> + struct atmel_tc *tc = platform_get_drvdata(pdev);
> +
> + for (i = 0; i < 3; i++)
> + writel(ATMEL_TC_ALL_IRQ, tc->regs + ATMEL_TC_REG(i, IDR));
> +}
> +
> static struct platform_driver tc_driver = {
> .driver = {
> .name = "atmel_tcb",
> .of_match_table = of_match_ptr(atmel_tcb_dt_ids),
> },
> + .shutdown = tc_shutdown,
> };
>
> static int __init tc_init(void)
> diff --git a/include/linux/atmel_tc.h b/include/linux/atmel_tc.h
> index d8aa884..b87c1c7 100644
> --- a/include/linux/atmel_tc.h
> +++ b/include/linux/atmel_tc.h
> @@ -260,5 +260,10 @@ extern const u8 atmel_tc_divisors[5];
> #define ATMEL_TC_LDRAS (1 << 5) /* RA loading */
> #define ATMEL_TC_LDRBS (1 << 6) /* RB loading */
> #define ATMEL_TC_ETRGS (1 << 7) /* external trigger */
> +#define ATMEL_TC_ALL_IRQ (ATMEL_TC_COVFS | ATMEL_TC_LOVRS | \
> + ATMEL_TC_CPAS | ATMEL_TC_CPBS | \
> + ATMEL_TC_CPCS | ATMEL_TC_LDRAS | \
> + ATMEL_TC_LDRBS | ATMEL_TC_ETRGS) \
> + /* all IRQs */
>
> #endif
>
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