UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

ARM: 7880/1: Clear the IT state independent of the Thumb-2 mode 

The ARM architecture reference specifies that the IT state bits in the
PSR must be all zeros in ARM mode or behavior is unspecified.  On the
Qualcomm Snapdragon S4/Krait architecture CPUs the processor continues
to consider the IT state bits while in ARM mode.  This makes it so
that some instructions are skipped by the CPU.

Signed-off-by: T.J. Purtell <tj@mobisocial.us>
[rmk+kernel@arm.linux.org.uk: fixed whitespace formatting in patch]
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
T.J. Purtell 2013-11-06 18:38:05 +01:00 committed by Russell King
parent e16b31bf47
commit 6ecf830e50
1 changed files with 10 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
arch/arm/kernel/signal.c
View File

@ -375,12 +375,18 @@ setup_return(struct pt_regs *regs, struct ksignal *ksig,
*/
thumb = handler & 1;
#if __LINUX_ARM_ARCH__ >= 7
/*
* Clear the If-Then Thumb-2 execution state
* ARM spec requires this to be all 000s in ARM mode
* Snapdragon S4/Krait misbehaves on a Thumb=>ARM
* signal transition without this.
*/
cpsr &= ~PSR_IT_MASK;
#endif
if (thumb) {
cpsr |= PSR_T_BIT;
#if __LINUX_ARM_ARCH__ >= 7
/* clear the If-Then Thumb-2 execution state */
cpsr &= ~PSR_IT_MASK;
#endif
} else
cpsr &= ~PSR_T_BIT;
}