Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
index 2c4d5ec..294ed43 100644
--- a/arch/x86/kernel/aperture_64.c
+++ b/arch/x86/kernel/aperture_64.c
@@ -14,6 +14,7 @@
 #define pr_fmt(fmt) "AGP: " fmt
 
 #include <linux/kernel.h>
+#include <linux/kcore.h>
 #include <linux/types.h>
 #include <linux/init.h>
 #include <linux/memblock.h>
@@ -57,7 +58,7 @@
 
 int fix_aperture __initdata = 1;
 
-#ifdef CONFIG_PROC_VMCORE
+#if defined(CONFIG_PROC_VMCORE) || defined(CONFIG_PROC_KCORE)
 /*
  * If the first kernel maps the aperture over e820 RAM, the kdump kernel will
  * use the same range because it will remain configured in the northbridge.
@@ -66,20 +67,25 @@
  */
 static unsigned long aperture_pfn_start, aperture_page_count;
 
-static int gart_oldmem_pfn_is_ram(unsigned long pfn)
+static int gart_mem_pfn_is_ram(unsigned long pfn)
 {
 	return likely((pfn < aperture_pfn_start) ||
 		      (pfn >= aperture_pfn_start + aperture_page_count));
 }
 
-static void exclude_from_vmcore(u64 aper_base, u32 aper_order)
+static void __init exclude_from_core(u64 aper_base, u32 aper_order)
 {
 	aperture_pfn_start = aper_base >> PAGE_SHIFT;
 	aperture_page_count = (32 * 1024 * 1024) << aper_order >> PAGE_SHIFT;
-	WARN_ON(register_oldmem_pfn_is_ram(&gart_oldmem_pfn_is_ram));
+#ifdef CONFIG_PROC_VMCORE
+	WARN_ON(register_oldmem_pfn_is_ram(&gart_mem_pfn_is_ram));
+#endif
+#ifdef CONFIG_PROC_KCORE
+	WARN_ON(register_mem_pfn_is_ram(&gart_mem_pfn_is_ram));
+#endif
 }
 #else
-static void exclude_from_vmcore(u64 aper_base, u32 aper_order)
+static void exclude_from_core(u64 aper_base, u32 aper_order)
 {
 }
 #endif
@@ -264,18 +270,23 @@
 }
 early_param("gart_fix_e820", parse_gart_mem);
 
+/*
+ * With kexec/kdump, if the first kernel doesn't shut down the GART and the
+ * second kernel allocates a different GART region, there might be two
+ * overlapping GART regions present:
+ *
+ * - the first still used by the GART initialized in the first kernel.
+ * - (sub-)set of it used as normal RAM by the second kernel.
+ *
+ * which leads to memory corruptions and a kernel panic eventually.
+ *
+ * This can also happen if the BIOS has forgotten to mark the GART region
+ * as reserved.
+ *
+ * Try to update the e820 map to mark that new region as reserved.
+ */
 void __init early_gart_iommu_check(void)
 {
-	/*
-	 * in case it is enabled before, esp for kexec/kdump,
-	 * previous kernel already enable that. memset called
-	 * by allocate_aperture/__alloc_bootmem_nopanic cause restart.
-	 * or second kernel have different position for GART hole. and new
-	 * kernel could use hole as RAM that is still used by GART set by
-	 * first kernel
-	 * or BIOS forget to put that in reserved.
-	 * try to update e820 to make that region as reserved.
-	 */
 	u32 agp_aper_order = 0;
 	int i, fix, slot, valid_agp = 0;
 	u32 ctl;
@@ -469,7 +480,7 @@
 			 * may have allocated the range over its e820 RAM
 			 * and fixed up the northbridge
 			 */
-			exclude_from_vmcore(last_aper_base, last_aper_order);
+			exclude_from_core(last_aper_base, last_aper_order);
 
 			return 1;
 		}
@@ -515,7 +526,7 @@
 	 * overlap with the first kernel's memory. We can't access the
 	 * range through vmcore even though it should be part of the dump.
 	 */
-	exclude_from_vmcore(aper_alloc, aper_order);
+	exclude_from_core(aper_alloc, aper_order);
 
 	/* Fix up the north bridges */
 	for (i = 0; i < amd_nb_bus_dev_ranges[i].dev_limit; i++) {