mirror of https://github.com/OpenIPC/firmware.git
33 lines
1.0 KiB
Diff
33 lines
1.0 KiB
Diff
diff -drupN a/arch/arm64/xen/hypercall.S b/arch/arm64/xen/hypercall.S
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--- a/arch/arm64/xen/hypercall.S 2018-08-06 17:23:04.000000000 +0300
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+++ b/arch/arm64/xen/hypercall.S 2022-06-12 05:28:14.000000000 +0300
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@@ -49,6 +49,7 @@
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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+#include <asm/uaccess.h>
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#include <xen/interface/xen.h>
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@@ -91,6 +92,20 @@ ENTRY(privcmd_call)
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mov x2, x3
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mov x3, x4
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mov x4, x5
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+ /*
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+ * Privcmd calls are issued by the userspace. The kernel needs to
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+ * enable access to TTBR0_EL1 as the hypervisor would issue stage 1
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+ * translations to user memory via AT instructions. Since AT
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+ * instructions are not affected by the PAN bit (ARMv8.1), we only
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+ * need the explicit uaccess_enable/disable if the TTBR0 PAN emulation
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+ * is enabled (it implies that hardware UAO and PAN disabled).
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+ */
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+ uaccess_ttbr0_enable x6, x7, x8
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hvc XEN_IMM
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+
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+ /*
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+ * Disable userspace access from kernel once the hyp call completed.
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+ */
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+ uaccess_ttbr0_disable x6, x7
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ret
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ENDPROC(privcmd_call);
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