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Subject[PATCH] ARM: kexec: Fix panic after TLB are invalidated
Date
machine_kexec() need to set rw permission in text and rodata sections
to assign some variables (e.g. kexec_start_address). To do that at
the end (after flushing pdm in memory, etc.) it needs to invalidate
TLB [section] entries.

If during the TLB invalidation an interrupt occours, which might cause
a context switch, there is the risk to inject invalid TLBs, with ro
permissions.

When trying to assign .text labels, this lead to the following:

Unable to handle kernel paging request at virtual address 80112f38
pgd = fd7ef03e
[80112f38] *pgd=0001141e(bad)
Internal error: Oops: 80d [#1] PREEMPT SMP ARM
...

Signed-off-by: Giancarlo Ferrari <giancarlo.ferrari89@gmail.com>
---
arch/arm/kernel/machine_kexec.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index 5d84ad3..23e8816 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -174,6 +174,13 @@ void machine_kexec(struct kimage *image)

reboot_code_buffer = page_address(image->control_code_page);

+ /*
+ * If below part is not atomic TLB entries might be corrupted after TLB
+ * invalidation, which leads to Data Abort in .text variable assignment
+ */
+ raw_local_irq_disable();
+ local_fiq_disable();
+
/* Prepare parameters for reboot_code_buffer*/
set_kernel_text_rw();
kexec_start_address = image->start;
@@ -181,6 +188,9 @@ void machine_kexec(struct kimage *image)
kexec_mach_type = machine_arch_type;
kexec_boot_atags = image->arch.kernel_r2;

+ local_fiq_enable();
+ raw_local_irq_enable();
+
/* copy our kernel relocation code to the control code page */
reboot_entry = fncpy(reboot_code_buffer,
&relocate_new_kernel,
--
2.7.4
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