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From: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
To: ard.biesheuvel@linaro.org, mingo@kernel.org, kasong@redhat.com,
	hdegoede@redhat.com, matthewgarrett@google.com,
	linux-efi@vger.kernel.org
Subject: [PATCH 1/1] efi/libstub: Workaround for data abort on armv6z architecture
Date: Mon, 18 Nov 2019 19:42:52 +0200	[thread overview]
Message-ID: <20191118174252.26758-2-cristian.ciocaltea@gmail.com> (raw)
In-Reply-To: <20191118174252.26758-1-cristian.ciocaltea@gmail.com>

The armv6-eabihf toolchains generate some ldrd instructions
that trigger data abort on RaspberryPi Zero (ARM1176JZF-S CPU):

drivers/firmware/efi/libstub/efi-stub-helper.c:91
	*map->map_size =	*map->desc_size * 32;
    92c8:	e1c420d4 	ldrd	r2, [r4, #4]

This patch is a hack to instruct the compiler to avoid
using the problematic ldrd instructions.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
---
 drivers/firmware/efi/libstub/efi-stub-helper.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index 35dbc2791c97..8d7d27b8b9c2 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -86,9 +86,10 @@ efi_status_t efi_get_memory_map(efi_system_table_t *sys_table_arg,
 	efi_status_t status;
 	unsigned long key;
 	u32 desc_version;
+	unsigned long hack;
 
 	*map->desc_size =	sizeof(*m);
-	*map->map_size =	*map->desc_size * 32;
+	*map->map_size =	sizeof(*m) * 32;
 	*map->buff_size =	*map->map_size;
 again:
 	status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
@@ -111,7 +112,9 @@ efi_status_t efi_get_memory_map(efi_system_table_t *sys_table_arg,
 		 * exceed this headroom once we are ready to trigger
 		 * ExitBootServices()
 		 */
-		*map->map_size += *map->desc_size * EFI_MMAP_NR_SLACK_SLOTS;
+		hack = *map->desc_size * EFI_MMAP_NR_SLACK_SLOTS + 1;
+		*map->map_size += hack;
+		--(*map->map_size);
 		*map->buff_size = *map->map_size;
 		goto again;
 	}
-- 
2.17.1


  reply	other threads:[~2019-11-18 17:43 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-18 17:42 [PATCH 0/1] Temporary fix for data abort on armv6z EFI boot Cristian Ciocaltea
2019-11-18 17:42 ` Cristian Ciocaltea [this message]
2019-11-18 18:02 ` Ard Biesheuvel
2019-11-19  1:52   ` Heinrich Schuchardt
2019-11-18 18:10 ` Mark Rutland
2019-11-18 18:15   ` Ard Biesheuvel
2019-11-18 18:51     ` Mark Rutland
2019-11-18 19:41       ` Ard Biesheuvel
2019-11-19  3:15         ` Heinrich Schuchardt
2019-11-19  7:27           ` Guillaume Gardet

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