ARM: 9485/1: mm: acquire mmap write lock around show_pte() for user faultsgrafted

When CONFIG_DEBUG_USER=y, and cmdline "user_debug=31" is set,
a user fault may trigger show_pte() without any lock.
If another thread in the same process concurrently calls munmap(),
the page table pages may be freed while show_pte() is still traversing
them, causing a use-after-free in show_pte().

If CONFIG_ARM_LPAE=y, this may cause a kernel panic if the pages table
of PMD are freed when show_pte() is running.

Acquire mmap_write_lock() around show_pte() for user faults to fix the
contention.

For user faults, additionally restrict that show_pte() is called only
when the addr is a user-space address (addr < TASK_SIZE). This is because
the lock of tsk->mm only protects the virtual memory of user address space,
furthermore, dumping the page tables of a kernel-space address for user
faults is unnecessary and may have security implications.

Keep everything unchanged for kernel faults, because the kernel is
already in the "oops" state, acquiring a lock may risk a deadlock.

Co-developed-by: Qi Xi <xiqi2@huawei.com>

Fixes: 6d021b724481 ("ARM: dump pgd, pmd and pte states on unhandled data abort faults")
Link: https://lore.kernel.org/20260716014022.2823-1-xieyuanbin1@huawei.com
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Qi Xi <xiqi2@huawei.com>
Signed-off-by: Xie Yuanbin <xieyuanbin1@huawei.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

3 files changed, 89 insertions, 0 deletions

diff --git a/include/soc/imx/cpu.h b/include/soc/imx/cpu.h
new file mode 100644
index 000000000..0bf610aca
--- /dev/null
+++ b/include/soc/imx/cpu.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __IMX_CPU_H__
+#define __IMX_CPU_H__
+
+#define MXC_CPU_MX1		1
+#define MXC_CPU_MX21		21
+#define MXC_CPU_MX25		25
+#define MXC_CPU_MX27		27
+#define MXC_CPU_MX31		31
+#define MXC_CPU_MX35		35
+#define MXC_CPU_MX50		50
+#define MXC_CPU_MX51		51
+#define MXC_CPU_MX53		53
+#define MXC_CPU_IMX6SL		0x60
+#define MXC_CPU_IMX6DL		0x61
+#define MXC_CPU_IMX6SX		0x62
+#define MXC_CPU_IMX6Q		0x63
+#define MXC_CPU_IMX6UL		0x64
+#define MXC_CPU_IMX6ULL		0x65
+/* virtual cpu id for i.mx6ulz */
+#define MXC_CPU_IMX6ULZ		0x6b
+#define MXC_CPU_IMX6SLL		0x67
+#define MXC_CPU_IMX7D		0x72
+#define MXC_CPU_IMX7ULP		0xff
+
+#define MXC_CPU_VFx10		0x010
+#define MXC_CPU_VF500		0x500
+#define MXC_CPU_VF510		(MXC_CPU_VF500 | MXC_CPU_VFx10)
+#define MXC_CPU_VF600		0x600
+#define MXC_CPU_VF610		(MXC_CPU_VF600 | MXC_CPU_VFx10)
+
+#ifndef __ASSEMBLY__
+extern unsigned int __mxc_cpu_type;
+#endif
+
+#endif
diff --git a/include/soc/imx/cpuidle.h b/include/soc/imx/cpuidle.h
new file mode 100644
index 000000000..7d9202801
--- /dev/null
+++ b/include/soc/imx/cpuidle.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2016 Pengutronix, <kernel@pengutronix.de>
+ */
+
+#ifndef __SOC_IMX_CPUIDLE_H__
+#define __SOC_IMX_CPUIDLE_H__
+
+#if defined(CONFIG_CPU_IDLE) && defined(CONFIG_SOC_IMX6Q)
+void imx6q_cpuidle_fec_irqs_used(void);
+void imx6q_cpuidle_fec_irqs_unused(void);
+#else
+static inline void imx6q_cpuidle_fec_irqs_used(void) { }
+static inline void imx6q_cpuidle_fec_irqs_unused(void) { }
+#endif
+
+#endif /* __SOC_IMX_CPUIDLE_H__ */
diff --git a/include/soc/imx/revision.h b/include/soc/imx/revision.h
new file mode 100644
index 000000000..b122d2fc8
--- /dev/null
+++ b/include/soc/imx/revision.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2015 Linaro Ltd.
+ */
+
+#ifndef __SOC_IMX_REVISION_H__
+#define __SOC_IMX_REVISION_H__
+
+#define IMX_CHIP_REVISION_1_0		0x10
+#define IMX_CHIP_REVISION_1_1		0x11
+#define IMX_CHIP_REVISION_1_2		0x12
+#define IMX_CHIP_REVISION_1_3		0x13
+#define IMX_CHIP_REVISION_1_4		0x14
+#define IMX_CHIP_REVISION_1_5		0x15
+#define IMX_CHIP_REVISION_2_0		0x20
+#define IMX_CHIP_REVISION_2_1		0x21
+#define IMX_CHIP_REVISION_2_2		0x22
+#define IMX_CHIP_REVISION_2_3		0x23
+#define IMX_CHIP_REVISION_3_0		0x30
+#define IMX_CHIP_REVISION_3_1		0x31
+#define IMX_CHIP_REVISION_3_2		0x32
+#define IMX_CHIP_REVISION_3_3		0x33
+#define IMX_CHIP_REVISION_UNKNOWN	0xff
+
+int mx25_revision(void);
+int mx27_revision(void);
+int mx31_revision(void);
+int mx35_revision(void);
+int mx51_revision(void);
+int mx53_revision(void);
+
+unsigned int imx_get_soc_revision(void);
+void imx_print_silicon_rev(const char *cpu, int srev);
+
+#endif /* __SOC_IMX_REVISION_H__ */