[coreboot-gerrit] Patch set updated for coreboot: b8eb94f libpayload: ARM: Don't leave alignment checking on after the exception test

Stefan Reinauer (stefan.reinauer@coreboot.org) gerrit at coreboot.org
Tue Nov 26 20:27:39 CET 2013

Stefan Reinauer (stefan.reinauer at coreboot.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/4255


commit b8eb94f8da6fa858f7bd9bdde56b4cf3f2eb603a
Author: Gabe Black <gabeblack at google.com>
Date:   Wed Jun 19 20:48:06 2013 -0700

    libpayload: ARM: Don't leave alignment checking on after the exception test
    Currently, the exception handling code on ARM in libpayload turns on alignment
    checks as an easy way to generate an exception for testing purposes. It was
    leaving it on which disabled unaligned accesses for other, unlreated code
    running later. This change adjusts the code so the original value of the
    alignment bit is restored after the test exception.
    Built and booted into depthcharge on pit with an unaligned accesses added
    after the call to exception_init in the depthcharge's main. Before this
    change, the access caused an exception. After this change, the access
    completed successfully.
    Change-Id: If92cab3cc8eabca7c5b0560ce88a8796a27fe3b2
    Signed-off-by: Gabe Black <gabeblack at google.com>
    Reviewed-on: https://gerrit.chromium.org/gerrit/59372
    Reviewed-by: Stefan Reinauer <reinauer at google.com>
    Commit-Queue: Gabe Black <gabeblack at chromium.org>
    Tested-by: Gabe Black <gabeblack at chromium.org>
 payloads/libpayload/arch/armv7/exception.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/payloads/libpayload/arch/armv7/exception.c b/payloads/libpayload/arch/armv7/exception.c
index 5e4e23d..9efc312 100644
--- a/payloads/libpayload/arch/armv7/exception.c
+++ b/payloads/libpayload/arch/armv7/exception.c
@@ -143,9 +143,8 @@ void exception_init(void)
 	sctlr &= ~sctlr_te;
 	/* Set V=0 in SCTLR so VBAR points to the exception vector table. */
 	sctlr &= ~sctlr_v;
-	/* Enforce alignment. */
-	sctlr |= sctlr_a;
-	set_sctlr(sctlr);
+	/* Enforce alignment temporarily. */
+	set_sctlr(sctlr | sctlr_a);
 	extern uint32_t exception_table[];
@@ -153,4 +152,7 @@ void exception_init(void)
 	test_abort = 1;
 	test_abort = 0;
+	/* Restore alignment settings. */
+	set_sctlr(sctlr);

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