[PATCH v2] efi/libstub: arm*: Pass latest memory map to the kernel

* [PATCH v2] efi/libstub: arm*: Pass latest memory map to the kernel
@ 2016-12-19 14:24 ` James Morse
  0 siblings, 0 replies; 8+ messages in thread
From: James Morse @ 2016-12-19 14:24 UTC (permalink / raw)
  To: linux-efi; +Cc: matt, jhugo, linux-arm-kernel, Ard Biesheuvel

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

As reported by James, the current libstub code involving the annotated
memory map only works somewhat correctly by accident, due to the fact
that a pool allocation happens to be reused immediately, retaining its
former contents.

Instead of juggling memory maps, which makes the code more complex than
it needs to be, simply put a placholder value into the FDT, and only
write the actual value after ExitBootServices() has been called.

Reported-by: James Morse <james.morse@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
[Update mmap-size too, remove updated_fdt()s unused params and header entry]
Signed-off-by: James Morse <james.morse@arm.com>
---
Hi Ard,

This is a v2 of your patch that updates the mmap-size too. This solves the
truncated memmap problem I saw with v1 on Seattle.

The original patch was CC-stable, so I think this should also have:
Cc: <stable@vger.kernel.org>
Fixes: ed9cc156c42f ("efi/libstub: Use efi_exit_boot_services() in FDT")


Thanks,

James

 drivers/firmware/efi/libstub/efistub.h |  8 ----
 drivers/firmware/efi/libstub/fdt.c     | 75 +++++++++++++++++++++-------------
 2 files changed, 47 insertions(+), 36 deletions(-)

diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
index ee49cd23ee63..fac67992bede 100644
--- a/drivers/firmware/efi/libstub/efistub.h
+++ b/drivers/firmware/efi/libstub/efistub.h
@@ -30,14 +30,6 @@ efi_status_t efi_file_close(void *handle);
 
 unsigned long get_dram_base(efi_system_table_t *sys_table_arg);
 
-efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
-			unsigned long orig_fdt_size,
-			void *fdt, int new_fdt_size, char *cmdline_ptr,
-			u64 initrd_addr, u64 initrd_size,
-			efi_memory_desc_t *memory_map,
-			unsigned long map_size, unsigned long desc_size,
-			u32 desc_ver);
-
 efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
 					    void *handle,
 					    unsigned long *new_fdt_addr,
diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index a6a93116a8f0..6d33d709f6b3 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -16,13 +16,11 @@
 
 #include "efistub.h"
 
-efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
-			unsigned long orig_fdt_size,
-			void *fdt, int new_fdt_size, char *cmdline_ptr,
-			u64 initrd_addr, u64 initrd_size,
-			efi_memory_desc_t *memory_map,
-			unsigned long map_size, unsigned long desc_size,
-			u32 desc_ver)
+static efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
+			       unsigned long orig_fdt_size,
+			       void *fdt, int new_fdt_size, char *cmdline_ptr,
+			       u64 initrd_addr, u64 initrd_size,
+			       unsigned long desc_size, u32 desc_ver)
 {
 	int node, num_rsv;
 	int status;
@@ -101,13 +99,13 @@ efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 	if (status)
 		goto fdt_set_fail;
 
-	fdt_val64 = cpu_to_fdt64((u64)(unsigned long)memory_map);
+	fdt_val64 = U64_MAX; /* placeholder */
 	status = fdt_setprop(fdt, node, "linux,uefi-mmap-start",
 			     &fdt_val64,  sizeof(fdt_val64));
 	if (status)
 		goto fdt_set_fail;
 
-	fdt_val32 = cpu_to_fdt32(map_size);
+	fdt_val32 = U32_MAX; /* placeholder */
 	status = fdt_setprop(fdt, node, "linux,uefi-mmap-size",
 			     &fdt_val32,  sizeof(fdt_val32));
 	if (status)
@@ -148,6 +146,32 @@ efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 	return EFI_LOAD_ERROR;
 }
 
+static efi_status_t update_fdt_memmap(void *fdt, u64 memmap, u32 map_size)
+{
+	int node = fdt_path_offset(fdt, "/chosen");
+	efi_status_t status;
+
+	if (node < 0)
+		return EFI_LOAD_ERROR;
+
+	memmap = cpu_to_fdt64(memmap);
+	status = fdt_setprop_inplace(fdt, node, "linux,uefi-mmap-start",
+				     &memmap, sizeof(memmap));
+
+	if (status)
+		return EFI_LOAD_ERROR;
+
+	map_size = cpu_to_fdt32(map_size);
+	status = fdt_setprop_inplace(fdt, node, "linux,uefi-mmap-size",
+				     &map_size, sizeof(map_size));
+
+	if (status)
+		return EFI_LOAD_ERROR;
+
+
+	return EFI_SUCCESS;
+}
+
 #ifndef EFI_FDT_ALIGN
 #define EFI_FDT_ALIGN EFI_PAGE_SIZE
 #endif
@@ -243,20 +267,11 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
 			goto fail;
 		}
 
-		/*
-		 * Now that we have done our final memory allocation (and free)
-		 * we can get the memory map key  needed for
-		 * exit_boot_services().
-		 */
-		status = efi_get_memory_map(sys_table, &map);
-		if (status != EFI_SUCCESS)
-			goto fail_free_new_fdt;
-
 		status = update_fdt(sys_table,
 				    (void *)fdt_addr, fdt_size,
 				    (void *)*new_fdt_addr, new_fdt_size,
 				    cmdline_ptr, initrd_addr, initrd_size,
-				    memory_map, map_size, desc_size, desc_ver);
+				    desc_size, desc_ver);
 
 		/* Succeeding the first time is the expected case. */
 		if (status == EFI_SUCCESS)
@@ -266,20 +281,16 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
 			/*
 			 * We need to allocate more space for the new
 			 * device tree, so free existing buffer that is
-			 * too small.  Also free memory map, as we will need
-			 * to get new one that reflects the free/alloc we do
-			 * on the device tree buffer.
+			 * too small.
 			 */
 			efi_free(sys_table, new_fdt_size, *new_fdt_addr);
-			sys_table->boottime->free_pool(memory_map);
 			new_fdt_size += EFI_PAGE_SIZE;
 		} else {
 			pr_efi_err(sys_table, "Unable to construct new device tree.\n");
-			goto fail_free_mmap;
+			goto fail_free_new_fdt;
 		}
 	}
 
-	sys_table->boottime->free_pool(memory_map);
 	priv.runtime_map = runtime_map;
 	priv.runtime_entry_count = &runtime_entry_count;
 	status = efi_exit_boot_services(sys_table, handle, &map, &priv,
@@ -288,6 +299,17 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
 	if (status == EFI_SUCCESS) {
 		efi_set_virtual_address_map_t *svam;
 
+		status = update_fdt_memmap((void *)*new_fdt_addr,
+					   (u64)memory_map, (u32)map_size);
+		if (status != EFI_SUCCESS) {
+			/*
+			 * The kernel won't get far without the memory map, but
+			 * may still be able to print something meaningful so
+			 * return success here.
+			 */
+			return EFI_SUCCESS;
+		}
+
 		/* Install the new virtual address map */
 		svam = sys_table->runtime->set_virtual_address_map;
 		status = svam(runtime_entry_count * desc_size, desc_size,
@@ -319,9 +341,6 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
 
 	pr_efi_err(sys_table, "Exit boot services failed.\n");
 
-fail_free_mmap:
-	sys_table->boottime->free_pool(memory_map);
-
 fail_free_new_fdt:
 	efi_free(sys_table, new_fdt_size, *new_fdt_addr);
 
-- 
2.10.1

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