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

James Morse
2016-12-19T14:24:19Z

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