linux-kernel - [PATCH 07/17] Enforce minimum alignment of 1 page on allocations. The efi_high_alloc() and efi_low_alloc() functions use the EFI_ALLOCATE_ADDRESS option to the EFI function allocate_pages(), which requires a minimum of page alignment, and rejects all other requests.

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Date:	Tue,  6 Aug 2013 20:45:03 -0700
From:	Roy Franz <roy.franz@...aro.org>
To:	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, matt.fleming@...el.com,
	linux@....linux.org.uk
Cc:	leif.lindholm@...aro.org, dave.martin@....com,
	Roy Franz <roy.franz@...aro.org>
Subject: [PATCH 07/17] Enforce minimum alignment of 1 page on allocations. The efi_high_alloc() and efi_low_alloc() functions use the EFI_ALLOCATE_ADDRESS option to the EFI function allocate_pages(), which requires a minimum of page alignment, and rejects all other requests.

The existing code could fail to allocate depending
on allocation size, as although repeated allocation
attempts were made, none were guaranteed to be page
aligned.



Signed-off-by: Roy Franz <roy.franz@...aro.org>
---
 drivers/firmware/efi/efi-stub-helper.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/firmware/efi/efi-stub-helper.c b/drivers/firmware/efi/efi-stub-helper.c
index cd7701f..8582650 100644
--- a/drivers/firmware/efi/efi-stub-helper.c
+++ b/drivers/firmware/efi/efi-stub-helper.c
@@ -105,6 +105,13 @@ static efi_status_t efi_high_alloc(efi_system_table_t *sys_table_arg,
 	if (status != EFI_SUCCESS)
 		goto fail;
 
+	/* Enforce minimum alignment that EFI requires when requesting
+	 * a specific address.  We are doing page-based allocations,
+	 * so we must be aligned to a page.
+	 */
+	if (align < EFI_PAGE_SIZE)
+		align = EFI_PAGE_SIZE;
+
 	nr_pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
 again:
 	for (i = 0; i < map_size / desc_size; i++) {
@@ -184,6 +191,13 @@ static efi_status_t efi_low_alloc(efi_system_table_t *sys_table_arg,
 	if (status != EFI_SUCCESS)
 		goto fail;
 
+	/* Enforce minimum alignment that EFI requires when requesting
+	 * a specific address.  We are doing page-based allocations,
+	 * so we must be aligned to a page.
+	 */
+	if (align < EFI_PAGE_SIZE)
+		align = EFI_PAGE_SIZE;
+
 	nr_pages = round_up(size, EFI_PAGE_SIZE) / EFI_PAGE_SIZE;
 	for (i = 0; i < map_size / desc_size; i++) {
 		efi_memory_desc_t *desc;
-- 
1.7.10.4

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