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94 lines
3.0 KiB
Diff
94 lines
3.0 KiB
Diff
From fdf4850cb5b2e5e549a18b8b41abb001bfb19e9c Mon Sep 17 00:00:00 2001
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From: Hauke Mehrtens <hauke@hauke-m.de>
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Date: Tue, 4 Feb 2014 00:01:46 +0100
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Subject: [PATCH 3/3] ARM: BCM5301X: workaround suppress fault
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Without this patch I am getting a unhandled fault exception like this
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one after "Freeing unused kernel memory":
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Freeing unused kernel memory: 1260K (c02c1000 - c03fc000)
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Unhandled fault: imprecise external abort (0x1c06) at 0xb6f89005
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Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000007
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The address which is here 0xb6f89005 changes from boot to boot, with a
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new build the changes are bigger. With kernel 3.10 I have also seen
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this fault at different places in the boot process, but starting with
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3.11 they are always occurring after the "Freeing unused kernel memory"
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message. I never was able to completely boot to userspace without this
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handler. The abort code is constant 0x1c06. This fault just happens
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once in the boot process I have never seen it happing twice or more.
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I also tried changing the CPSR.A bit to 0 in init_early, with this code
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like Afzal suggested, but that did not change anything:
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asm volatile("mrs r12, cpsr\n"
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"bic r12, r12, #0x00000100\n"
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"msr cpsr_c, r12" ::: "r12", "cc", "memory");
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Disabling the L2 cache by building with CONFIG_CACHE_L2X0 unset did not
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help.
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This workaround was copied from the vendor code including most of the
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comments. It says it they think this is caused by the CFE boot loader
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used on this device. I do not have any access to any datasheet or
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errata document to check this.
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Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
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Acked-by: Arnd Bergmann <arnd@arndb.de>
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Acked-by: Christian Daudt <bcm@fixthebug.org>
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Signed-off-by: Matt Porter <mporter@linaro.org>
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---
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arch/arm/mach-bcm/bcm_5301x.c | 33 +++++++++++++++++++++++++++++++++
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1 file changed, 33 insertions(+)
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--- a/arch/arm/mach-bcm/bcm_5301x.c
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+++ b/arch/arm/mach-bcm/bcm_5301x.c
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@@ -9,8 +9,40 @@
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#include <asm/hardware/cache-l2x0.h>
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#include <asm/mach/arch.h>
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+#include <asm/siginfo.h>
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+#include <asm/signal.h>
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+static bool first_fault = true;
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+
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+static int bcm5301x_abort_handler(unsigned long addr, unsigned int fsr,
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+ struct pt_regs *regs)
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+{
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+ if (fsr == 0x1c06 && first_fault) {
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+ first_fault = false;
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+
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+ /*
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+ * These faults with code 0x1c06 happens for no good reason,
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+ * possibly left over from the CFE boot loader.
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+ */
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+ pr_warn("External imprecise Data abort at addr=%#lx, fsr=%#x ignored.\n",
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+ addr, fsr);
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+
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+ /* Returning non-zero causes fault display and panic */
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+ return 0;
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+ }
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+
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+ /* Others should cause a fault */
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+ return 1;
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+}
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+
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+static void __init bcm5301x_init_early(void)
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+{
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+ /* Install our hook */
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+ hook_fault_code(16 + 6, bcm5301x_abort_handler, SIGBUS, BUS_OBJERR,
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+ "imprecise external abort");
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+}
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+
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static void __init bcm5301x_dt_init(void)
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{
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l2x0_of_init(0, ~0UL);
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@@ -23,6 +55,7 @@ static const char __initconst *bcm5301x_
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};
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DT_MACHINE_START(BCM5301X, "BCM5301X")
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+ .init_early = bcm5301x_init_early,
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.init_machine = bcm5301x_dt_init,
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.dt_compat = bcm5301x_dt_compat,
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MACHINE_END
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