[PATCH v3] ACPI / x86: introduce acpi_os_readable() support

[Lv Zheng]

From: Chen Yu <yu.c.chen@xxxxxxxxx>

This patch implements acpi_os_readable(). The function is used by ACPICA
AML debugger to validate user specified pointers for dumping the memory as
ACPICA descriptor objects.

Signed-off-by: Chen Yu <yu.c.chen@xxxxxxxxx>
Tested-by: Lv Zheng <lv.zheng@xxxxxxxxx>
Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
---
 arch/x86/Kconfig                  |    1 +
 arch/x86/include/asm/acenv.h      |    1 +
 arch/x86/kernel/acpi/boot.c       |   44 +++++++++++++++++++++++++++++++++++++
 drivers/acpi/Kconfig              |    3 +++
 drivers/acpi/osl.c                |   12 ++++++++++
 include/acpi/platform/aclinux.h   |    1 -
 include/acpi/platform/aclinuxex.h |    5 -----
 7 files changed, 61 insertions(+), 6 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 96d058a..25585ee 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -19,6 +19,7 @@ config X86
 	def_bool y
 	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
 	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
+	select ACPI_MEMORY_ACCESS_CHECK_SUPPORT	if ACPI
 	select ANON_INODES
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_DISCARD_MEMBLOCK
diff --git a/arch/x86/include/asm/acenv.h b/arch/x86/include/asm/acenv.h
index 1b010a8..a2a2849 100644
--- a/arch/x86/include/asm/acenv.h
+++ b/arch/x86/include/asm/acenv.h
@@ -20,6 +20,7 @@
 
 int __acpi_acquire_global_lock(unsigned int *lock);
 int __acpi_release_global_lock(unsigned int *lock);
+bool __acpi_memory_readable(void *pointer, size_t length);
 
 #define ACPI_ACQUIRE_GLOBAL_LOCK(facs, Acq) \
 	((Acq) = __acpi_acquire_global_lock(&facs->global_lock))
diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index e759076..4a5e22e 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1699,6 +1699,50 @@ int __acpi_release_global_lock(unsigned int *lock)
 	return old & 0x1;
 }
 
+bool __acpi_memory_readable(void *pointer, size_t length)
+{
+	unsigned long obj_start, obj_end;
+	unsigned long start_pfn, end_pfn;
+
+	/*
+	 * All direct mapped PFNs should have been recorded by the mapped
+	 * PFN ranges. But pfn_range_is_mapped() requires the following
+	 * sanity checks to be performed before invoking.
+	 */
+	obj_start = ACPI_TO_INTEGER(pointer);
+	obj_end = obj_start + length;
+
+	/*
+	 * ACPICA core doesn't validate if the object is wrapped over, so
+	 * we should.
+	 */
+	if (length && (obj_end - 1) < obj_start)
+		return false;
+
+	/*
+	 * None direct mapping ranges contain holes. For example, high
+	 * kernel map holes (lower than _text or higher than _brk_end).
+	 * Converting a virtual address that belongs to the high map hole
+	 * results in a valid PFN because its low map has been recorded as
+	 * a mapped range.
+	 */
+	if (obj_start < PAGE_OFFSET ||
+	    obj_start >= (unsigned long)high_memory ||
+	    (length && (obj_end - 1) >= (unsigned long)high_memory))
+		return false;
+
+	/*
+	 * It is required to pass a range (end_pfn - start_pfn > 0) to
+	 * pfn_range_is_mapped().
+	 */
+	start_pfn = PFN_DOWN(__pa(obj_start));
+	end_pfn = PFN_UP(__pa(obj_end));
+	if (unlikely(end_pfn == start_pfn))
+		end_pfn++;
+
+	return pfn_range_is_mapped(start_pfn, end_pfn);
+}
+
 void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)
 {
 	e820_add_region(addr, size, E820_ACPI);
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index c4d4a05..73b45f9 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -57,6 +57,9 @@ config ACPI_SYSTEM_POWER_STATES_SUPPORT
 config ACPI_CCA_REQUIRED
 	bool
 
+config ACPI_MEMORY_ACCESS_CHECK_SUPPORT
+	bool
+
 config ACPI_DEBUGGER
 	bool "In-kernel debugger"
 	select ACPI_DEBUG
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index ce5ac00..edec035 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -1582,6 +1582,18 @@ acpi_status acpi_os_get_line(char *buffer, u32 buffer_length, u32 *bytes_read)
 }
 EXPORT_SYMBOL(acpi_os_get_line);
 
+#ifdef CONFIG_ACPI_MEMORY_ACCESS_CHECK_SUPPORT
+u8 acpi_os_readable(void *pointer, acpi_size length)
+{
+	return __acpi_memory_readable(pointer, length) ? TRUE : FALSE;
+}
+#else
+u8 acpi_os_readable(void *pointer, acpi_size length)
+{
+	return TRUE;
+}
+#endif
+
 acpi_status acpi_os_wait_command_ready(void)
 {
 	int ret;
diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h
index e21857d..b3c493e 100644
--- a/include/acpi/platform/aclinux.h
+++ b/include/acpi/platform/aclinux.h
@@ -148,7 +148,6 @@
 /*
  * OSL interfaces used by debugger/disassembler
  */
-#define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_readable
 #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_writable
 #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_initialize_command_signals
 #define ACPI_USE_ALTERNATE_PROTOTYPE_acpi_os_terminate_command_signals
diff --git a/include/acpi/platform/aclinuxex.h b/include/acpi/platform/aclinuxex.h
index ceea026..94bead6 100644
--- a/include/acpi/platform/aclinuxex.h
+++ b/include/acpi/platform/aclinuxex.h
@@ -124,11 +124,6 @@ static inline acpi_thread_id acpi_os_get_thread_id(void)
 		lock ? AE_OK : AE_NO_MEMORY; \
 	})
 
-static inline u8 acpi_os_readable(void *pointer, acpi_size length)
-{
-	return TRUE;
-}
-
 static inline acpi_status acpi_os_initialize_command_signals(void)
 {
 	return AE_OK;
-- 
1.7.10

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