From: Prarit Bhargava <prarit@redhat.com>
Date: Mon, 16 Feb 2009 07:21:52 -0500
Subject: [acpi] use vmalloc in acpi_system_read_dsdt
Message-id: 20090216122151.4651.21452.sendpatchset@prarit.bos.redhat.com
O-Subject: [RHEL5 PATCH]: Use vmalloc in acpi_system_read_dsdt()
Bugzilla: 480142
RH-Acked-by: Pete Zaitcev <zaitcev@redhat.com>

PrimeQuest systems have a large DSDT table, larger than kmalloc can handle.
Use vmalloc instead of kmalloc in acpi_system_read_dsdt() to allow for large
DSDTs.

Upstream is significantly different and does not require this patch.

Tested by jmoyer on a PrimeQuest system in RHTS, and the resulting output from
/proc/acpi/dsdt was passed into Intel's ASL which resulted in proper decoded
output.

Resolves BZ 480142.

diff --git a/drivers/acpi/system.c b/drivers/acpi/system.c
index d86dcb3..052cd4b 100644
--- a/drivers/acpi/system.c
+++ b/drivers/acpi/system.c
@@ -26,9 +26,11 @@
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/init.h>
+#include <linux/vmalloc.h>
 #include <asm/uaccess.h>
 
 #include <acpi/acpi_drivers.h>
+#include <acpi/actables.h>
 
 #define _COMPONENT		ACPI_SYSTEM_COMPONENT
 ACPI_MODULE_NAME("acpi_system")
@@ -76,17 +78,26 @@ acpi_system_read_dsdt(struct file *file,
 		      char __user * buffer, size_t count, loff_t * ppos)
 {
 	acpi_status status = AE_OK;
-	struct acpi_buffer dsdt = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct acpi_table_header *tbl_ptr;
 	ssize_t res;
+	void *ptr;
 
-
-	status = acpi_get_table(ACPI_TABLE_ID_DSDT, 1, &dsdt);
+	status = acpi_tb_get_table_ptr(ACPI_TABLE_ID_DSDT, 1, &tbl_ptr);
 	if (ACPI_FAILURE(status))
 		return -ENODEV;
 
-	res = simple_read_from_buffer(buffer, count, ppos,
-				      dsdt.pointer, dsdt.length);
-	kfree(dsdt.pointer);
+	ptr = vmalloc(tbl_ptr->length);
+	if (!ptr)
+		return -ENOMEM;
+
+	ACPI_MEMSET(ptr, 0, tbl_ptr->length);
+
+	ACPI_MEMCPY(ACPI_CAST_PTR(void, ptr),
+		    ACPI_CAST_PTR(void, tbl_ptr), tbl_ptr->length);
+
+	res = simple_read_from_buffer(buffer, count, ppos, ptr,
+				      tbl_ptr->length);
+	vfree(ptr);
 
 	return res;
 }