Skip site navigation (1)Skip section navigation (2) 
Date:      Thu, 2 Mar 2017 07:25:50 +0000 (UTC)
From:      Dexuan Cui <dexuan@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r314547 - head/sys/boot/efi/loader
Message-ID:  <201703020725.v227Pom1057031@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help 
Author: dexuan
Date: Thu Mar  2 07:25:50 2017
New Revision: 314547
URL: https://svnweb.freebsd.org/changeset/base/314547

Log:
  loader.efi: reduce the size of the staging area if necessary
  
  The loader assumes physical memory in [2MB, 2MB + EFI_STAGING_SIZE)
  is Conventional Memory, but actually it may not, e.g. in the case
  of Hyper-V Generation-2 VM (i.e. UEFI VM) running on Windows
  Server 2012 R2 host, there is a BootServiceData memory block at
  the address 47.449MB and the memory is not writable.
  
  Without the patch, the loader will crash in efi_copy_finish():
  see PR 211746.
  
  The patch verifies the end of the staging area, and reduces its
  size if necessary. This way, the loader will not try to write into
  the BootServiceData memory any longer.
  
  Thank Marcel Moolenaar for helping me on this issue!
  
  The patch also allocates the staging area in the first 1GB memory.
  See the comment in the patch for this.
  
  PR:		211746
  Reviewed by:	marcel, kib, sephe
  Approved by:	sephe (mentor)
  MFC after:	2 weeks
  Sponsored by:	Microsoft
  Differential Revision:	https://reviews.freebsd.org/D9686

Modified:
  head/sys/boot/efi/loader/copy.c

Modified: head/sys/boot/efi/loader/copy.c
==============================================================================
--- head/sys/boot/efi/loader/copy.c	Thu Mar  2 06:57:13 2017	(r314546)
+++ head/sys/boot/efi/loader/copy.c	Thu Mar  2 07:25:50 2017	(r314547)
@@ -39,12 +39,71 @@ __FBSDID("$FreeBSD$");
 
 #include "loader_efi.h"
 
+#if defined(__i386__) || defined(__amd64__)
+
+#define KERNEL_PHYSICAL_BASE (2*1024*1024)
+
+static void
+efi_verify_staging_size(unsigned long *nr_pages)
+{
+	UINTN sz;
+	EFI_MEMORY_DESCRIPTOR *map, *p;
+	EFI_PHYSICAL_ADDRESS start, end;
+	UINTN key, dsz;
+	UINT32 dver;
+	EFI_STATUS status;
+	int i, ndesc;
+	unsigned long available_pages;
+
+	sz = 0;
+	status = BS->GetMemoryMap(&sz, 0, &key, &dsz, &dver);
+	if (status != EFI_BUFFER_TOO_SMALL) {
+		printf("Can't determine memory map size\n");
+		return;
+	}
+
+	map = malloc(sz);
+	status = BS->GetMemoryMap(&sz, map, &key, &dsz, &dver);
+	if (EFI_ERROR(status)) {
+		printf("Can't read memory map\n");
+		goto out;
+	}
+
+	ndesc = sz / dsz;
+
+	for (i = 0, p = map; i < ndesc;
+	     i++, p = NextMemoryDescriptor(p, dsz)) {
+		start = p->PhysicalStart;
+		end = start + p->NumberOfPages * EFI_PAGE_SIZE;
+
+		if (KERNEL_PHYSICAL_BASE < start ||
+		    KERNEL_PHYSICAL_BASE >= end)
+			continue;
+
+		if (p->Type != EfiConventionalMemory)
+			continue;
+
+		available_pages = p->NumberOfPages -
+			((KERNEL_PHYSICAL_BASE - start) >> EFI_PAGE_SHIFT);
+
+		if (*nr_pages > available_pages) {
+			printf("staging area size is reduced: %ld -> %ld!\n",
+			    *nr_pages, available_pages);
+			*nr_pages = available_pages;
+		}
+
+		break;
+	}
+
+out:
+	free(map);
+}
+#endif
+
 #ifndef EFI_STAGING_SIZE
 #define	EFI_STAGING_SIZE	64
 #endif
 
-#define	STAGE_PAGES	EFI_SIZE_TO_PAGES((EFI_STAGING_SIZE) * 1024 * 1024)
-
 EFI_PHYSICAL_ADDRESS	staging, staging_end;
 int			stage_offset_set = 0;
 ssize_t			stage_offset;
@@ -54,14 +113,32 @@ efi_copy_init(void)
 {
 	EFI_STATUS	status;
 
+	unsigned long nr_pages;
+
+	nr_pages = EFI_SIZE_TO_PAGES((EFI_STAGING_SIZE) * 1024 * 1024);
+
+#if defined(__i386__) || defined(__amd64__)
+	/* We'll decrease nr_pages, if it's too big. */
+	efi_verify_staging_size(&nr_pages);
+
+	/*
+	 * The staging area must reside in the the first 1GB physical
+	 * memory: see elf64_exec() in
+	 * boot/efi/loader/arch/amd64/elf64_freebsd.c.
+	 */
+	staging = 1024*1024*1024;
+	status = BS->AllocatePages(AllocateMaxAddress, EfiLoaderData,
+	    nr_pages, &staging);
+#else
 	status = BS->AllocatePages(AllocateAnyPages, EfiLoaderData,
-	    STAGE_PAGES, &staging);
+	    nr_pages, &staging);
+#endif
 	if (EFI_ERROR(status)) {
 		printf("failed to allocate staging area: %lu\n",
 		    EFI_ERROR_CODE(status));
 		return (status);
 	}
-	staging_end = staging + STAGE_PAGES * EFI_PAGE_SIZE;
+	staging_end = staging + nr_pages * EFI_PAGE_SIZE;
 
 #if defined(__aarch64__) || defined(__arm__)
 	/*

Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201703020725.v227Pom1057031>