[PATCH v3 2/4] x86/acpi: take rsdp address for boot params if available

From: Juergen Gross
Date: Fri Dec 08 2017 - 10:12:15 EST


In case the rsdp address in struct boot_params is specified don't try
to find the table by searching, but take the address directly as set
by the boot loader.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V3: use a generic retrieval function with a __weak annotated default
function (Ingo Molnar)
---
arch/x86/kernel/acpi/boot.c | 7 +++++++
drivers/acpi/osl.c | 10 +++++++++-
include/linux/acpi.h | 2 ++
3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index f4c463df8b08..26fc8972dc4b 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -47,6 +47,7 @@
#include <asm/mpspec.h>
#include <asm/smp.h>
#include <asm/i8259.h>
+#include <asm/setup.h>

#include "sleep.h" /* To include x86_acpi_suspend_lowlevel */
static int __initdata acpi_force = 0;
@@ -1758,3 +1759,9 @@ void __init arch_reserve_mem_area(acpi_physical_address addr, size_t size)
e820__range_add(addr, size, E820_TYPE_ACPI);
e820__update_table_print();
}
+
+acpi_physical_address acpi_arch_get_root_pointer(void)
+{
+ return boot_params.hdr.acpi_rsdp_addr;
+}
+EXPORT_SYMBOL_GPL(acpi_arch_get_root_pointer);
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 3bb46cb24a99..2b77db914752 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -178,6 +178,11 @@ void acpi_os_vprintf(const char *fmt, va_list args)
#endif
}

+__weak acpi_physical_address acpi_arch_get_root_pointer(void)
+{
+ return 0;
+}
+
#ifdef CONFIG_KEXEC
static unsigned long acpi_rsdp;
static int __init setup_acpi_rsdp(char *arg)
@@ -189,12 +194,15 @@ early_param("acpi_rsdp", setup_acpi_rsdp);

acpi_physical_address __init acpi_os_get_root_pointer(void)
{
- acpi_physical_address pa = 0;
+ acpi_physical_address pa;

#ifdef CONFIG_KEXEC
if (acpi_rsdp)
return acpi_rsdp;
#endif
+ pa = acpi_arch_get_root_pointer();
+ if (pa)
+ return pa;

if (efi_enabled(EFI_CONFIG_TABLES)) {
if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index dc1ebfeeb5ec..aa603cc5ad30 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1266,4 +1266,6 @@ static inline int lpit_read_residency_count_address(u64 *address)
}
#endif

+acpi_physical_address acpi_arch_get_root_pointer(void);
+
#endif /*_LINUX_ACPI_H*/
--
2.12.3