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SubjectRe: [PATCHv3] x86: EFI stub support for large memory maps
On Sun, 22 Sep, at 07:59:08PM, Linn Crosetto wrote:
> This patch fixes a problem with EFI memory maps larger than 128 entries
> when booting using the EFI stub, which results in overflowing e820_map
> in boot_params and an eventual halt when checking the map size in
> sanitize_e820_map().
>
> If the number of map entries is greater than what can fit in e820_map,
> add the extra entries to the setup_data list using type SETUP_E820_EXT.
> These extra entries are then picked up when the setup_data list is
> parsed in parse_e820_ext().
>
> Signed-off-by: Linn Crosetto <linn@hp.com>
> ---
> Changes from v2:
> * Removed unnecessary optimization in alloc_e820ext() (Matt Fleming)
> * Fixed a bug where an incorrect buffer size may be passed to
> get_memory_map when jumping to get_map
>
> arch/x86/boot/compressed/eboot.c | 239 +++++++++++++++++++++++++++------------
> 1 file changed, 167 insertions(+), 72 deletions(-)

Thanks Linn. I applied this to the 'next' branch at,

git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi.git

but it required a bit of massaging to apply on top of the changes
already there. Could you confirm that my changes are OK? I've included
the modified commit below.

---

From 81c9e1df196ad531edabe726a2d7a610fb04fdd6 Mon Sep 17 00:00:00 2001
From: Linn Crosetto <linn@hp.com>
Date: Sun, 22 Sep 2013 19:59:08 -0600
Subject: [PATCH] x86: EFI stub support for large memory maps

This patch fixes a problem with EFI memory maps larger than 128 entries
when booting using the EFI stub, which results in overflowing e820_map
in boot_params and an eventual halt when checking the map size in
sanitize_e820_map().

If the number of map entries is greater than what can fit in e820_map,
add the extra entries to the setup_data list using type SETUP_E820_EXT.
These extra entries are then picked up when the setup_data list is
parsed in parse_e820_ext().

Signed-off-by: Linn Crosetto <linn@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
---
arch/x86/boot/compressed/eboot.c | 220 ++++++++++++++++++++++++++++-----------
1 file changed, 159 insertions(+), 61 deletions(-)

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index beb07a4..482006e 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -519,71 +519,47 @@ fail:
return NULL;
}

-static efi_status_t exit_boot(struct boot_params *boot_params,
- void *handle)
+static void add_e820ext(struct boot_params *params,
+ struct setup_data *e820ext, u32 nr_entries)
{
- struct efi_info *efi = &boot_params->efi_info;
- struct e820entry *e820_map = &boot_params->e820_map[0];
- struct e820entry *prev = NULL;
- unsigned long size, key, desc_size, _size;
- efi_memory_desc_t *mem_map;
+ struct setup_data *data;
efi_status_t status;
- __u32 desc_version;
- bool called_exit = false;
- u8 nr_entries;
- int i;
+ unsigned long size;

-get_map:
- status = efi_get_memory_map(sys_table, &mem_map, &size, &desc_size,
- &desc_version, &key);
+ e820ext->type = SETUP_E820_EXT;
+ e820ext->len = nr_entries * sizeof(struct e820entry);
+ e820ext->next = 0;

- if (status != EFI_SUCCESS)
- return status;
-
- memcpy(&efi->efi_loader_signature, EFI_LOADER_SIGNATURE, sizeof(__u32));
- efi->efi_systab = (unsigned long)sys_table;
- efi->efi_memdesc_size = desc_size;
- efi->efi_memdesc_version = desc_version;
- efi->efi_memmap = (unsigned long)mem_map;
- efi->efi_memmap_size = size;
-
-#ifdef CONFIG_X86_64
- efi->efi_systab_hi = (unsigned long)sys_table >> 32;
- efi->efi_memmap_hi = (unsigned long)mem_map >> 32;
-#endif
+ data = (struct setup_data *)(unsigned long)params->hdr.setup_data;

- /* Might as well exit boot services now */
- status = efi_call_phys2(sys_table->boottime->exit_boot_services,
- handle, key);
- if (status != EFI_SUCCESS) {
- /*
- * ExitBootServices() will fail if any of the event
- * handlers change the memory map. In which case, we
- * must be prepared to retry, but only once so that
- * we're guaranteed to exit on repeated failures instead
- * of spinning forever.
- */
- if (called_exit)
- goto free_mem_map;
+ while (data && data->next)
+ data = (struct setup_data *)(unsigned long)data->next;

- called_exit = true;
- efi_call_phys1(sys_table->boottime->free_pool, mem_map);
- goto get_map;
- }
+ if (data)
+ data->next = (unsigned long)e820ext;
+ else
+ params->hdr.setup_data = (unsigned long)e820ext;
+}

- /* Historic? */
- boot_params->alt_mem_k = 32 * 1024;
+static efi_status_t setup_e820(struct boot_params *params,
+ struct setup_data *e820ext, u32 e820ext_size)
+{
+ struct e820entry *e820_map = &params->e820_map[0];
+ struct efi_info *efi = &params->efi_info;
+ struct e820entry *prev = NULL;
+ u32 nr_entries;
+ u32 nr_desc;
+ int i;

- /*
- * Convert the EFI memory map to E820.
- */
nr_entries = 0;
- for (i = 0; i < size / desc_size; i++) {
+ nr_desc = efi->efi_memmap_size / efi->efi_memdesc_size;
+
+ for (i = 0; i < nr_desc; i++) {
efi_memory_desc_t *d;
unsigned int e820_type = 0;
- unsigned long m = (unsigned long)mem_map;
+ unsigned long m = efi->efi_memmap;

- d = (efi_memory_desc_t *)(m + (i * desc_size));
+ d = (efi_memory_desc_t *)(m + (i * efi->efi_memdesc_size));
switch (d->type) {
case EFI_RESERVED_TYPE:
case EFI_RUNTIME_SERVICES_CODE:
@@ -620,18 +596,140 @@ get_map:

/* Merge adjacent mappings */
if (prev && prev->type == e820_type &&
- (prev->addr + prev->size) == d->phys_addr)
+ (prev->addr + prev->size) == d->phys_addr) {
prev->size += d->num_pages << 12;
- else {
- e820_map->addr = d->phys_addr;
- e820_map->size = d->num_pages << 12;
- e820_map->type = e820_type;
- prev = e820_map++;
- nr_entries++;
+ continue;
}
+
+ if (nr_entries == ARRAY_SIZE(params->e820_map)) {
+ u32 need = (nr_desc - i) * sizeof(struct e820entry) +
+ sizeof(struct setup_data);
+
+ if (!e820ext || e820ext_size < need)
+ return EFI_BUFFER_TOO_SMALL;
+
+ /* boot_params map full, switch to e820 extended */
+ e820_map = (struct e820entry *)e820ext->data;
+ }
+
+ e820_map->addr = d->phys_addr;
+ e820_map->size = d->num_pages << PAGE_SHIFT;
+ e820_map->type = e820_type;
+ prev = e820_map++;
+ nr_entries++;
}

- boot_params->e820_entries = nr_entries;
+ if (nr_entries > ARRAY_SIZE(params->e820_map)) {
+ u32 nr_e820ext = nr_entries - ARRAY_SIZE(params->e820_map);
+
+ add_e820ext(params, e820ext, nr_e820ext);
+ nr_entries -= nr_e820ext;
+ }
+
+ params->e820_entries = (u8)nr_entries;
+
+ return EFI_SUCCESS;
+}
+
+static efi_status_t alloc_e820ext(u32 nr_desc, struct setup_data **e820ext,
+ u32 *e820ext_size)
+{
+ efi_status_t status;
+ unsigned long size;
+
+ size = sizeof(struct setup_data) +
+ sizeof(struct e820entry) * nr_desc;
+
+ if (*e820ext) {
+ efi_call_phys1(sys_table->boottime->free_pool, *e820ext);
+ *e820ext = NULL;
+ *e820ext_size = 0;
+ }
+
+ status = efi_call_phys3(sys_table->boottime->allocate_pool,
+ EFI_LOADER_DATA, size, e820ext);
+
+ if (status == EFI_SUCCESS)
+ *e820ext_size = size;
+
+ return status;
+}
+
+static efi_status_t exit_boot(struct boot_params *boot_params,
+ void *handle)
+{
+ struct efi_info *efi = &boot_params->efi_info;
+ unsigned long map_sz, key, desc_size;
+ efi_memory_desc_t *mem_map;
+ struct setup_data *e820ext;
+ __u32 e820ext_size;
+ __u32 nr_desc, prev_nr_desc;
+ efi_status_t status;
+ __u32 desc_version;
+ bool called_exit = false;
+ u8 nr_entries;
+ int i;
+
+ nr_desc = 0;
+ e820ext = NULL;
+ e820ext_size = 0;
+
+get_map:
+ status = efi_get_memory_map(sys_table, &mem_map, &map_sz, &desc_size,
+ &desc_version, &key);
+
+ if (status != EFI_SUCCESS)
+ return status;
+
+ prev_nr_desc = nr_desc;
+ nr_desc = map_sz / desc_size;
+ if (nr_desc > prev_nr_desc &&
+ nr_desc > ARRAY_SIZE(boot_params->e820_map)) {
+ u32 nr_e820ext = nr_desc - ARRAY_SIZE(boot_params->e820_map);
+
+ status = alloc_e820ext(nr_e820ext, &e820ext, &e820ext_size);
+ if (status != EFI_SUCCESS)
+ goto free_mem_map;
+
+ efi_call_phys1(sys_table->boottime->free_pool, mem_map);
+ goto get_map; /* Allocated memory, get map again */
+ }
+
+ memcpy(&efi->efi_loader_signature, EFI_LOADER_SIGNATURE, sizeof(__u32));
+ efi->efi_systab = (unsigned long)sys_table;
+ efi->efi_memdesc_size = desc_size;
+ efi->efi_memdesc_version = desc_version;
+ efi->efi_memmap = (unsigned long)mem_map;
+ efi->efi_memmap_size = map_sz;
+
+#ifdef CONFIG_X86_64
+ efi->efi_systab_hi = (unsigned long)sys_table >> 32;
+ efi->efi_memmap_hi = (unsigned long)mem_map >> 32;
+#endif
+
+ /* Might as well exit boot services now */
+ status = efi_call_phys2(sys_table->boottime->exit_boot_services,
+ handle, key);
+ if (status != EFI_SUCCESS) {
+ /*
+ * ExitBootServices() will fail if any of the event
+ * handlers change the memory map. In which case, we
+ * must be prepared to retry, but only once so that
+ * we're guaranteed to exit on repeated failures instead
+ * of spinning forever.
+ */
+ if (called_exit)
+ goto free_mem_map;
+
+ called_exit = true;
+ efi_call_phys1(sys_table->boottime->free_pool, mem_map);
+ goto get_map;
+ }
+
+ /* Historic? */
+ boot_params->alt_mem_k = 32 * 1024;
+
+ status = setup_e820(boot_params, e820ext, e820ext_size);

return EFI_SUCCESS;

--
1.8.1.4

--
Matt Fleming, Intel Open Source Technology Center


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