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ARM: use aliases for registers in entry-common

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Use aliases for the saved (and preserved) PSR and PC values so that we
can control which registers are used.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Russell King 2017-03-24 16:15:45 +00:00
parent fed3c15531
commit 309ee04257
1 changed files with 14 additions and 10 deletions
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24
arch/arm/kernel/entry-common.S
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@ -27,6 +27,8 @@
#include "entry-header.S"
saved_psr .req r8
saved_pc .req lr
.align 5
#if !(IS_ENABLED(CONFIG_TRACE_IRQFLAGS) || IS_ENABLED(CONFIG_CONTEXT_TRACKING))
@ -141,9 +143,9 @@ ENTRY(vector_swi)
ARM( stmdb r8, {sp, lr}^ ) @ Calling sp, lr
THUMB( mov r8, sp )
THUMB( store_user_sp_lr r8, r10, S_SP ) @ calling sp, lr
mrs r8, spsr @ called from non-FIQ mode, so ok.
str lr, [sp, #S_PC] @ Save calling PC
str r8, [sp, #S_PSR] @ Save CPSR
mrs saved_psr, spsr @ called from non-FIQ mode, so ok.
str saved_pc, [sp, #S_PC] @ Save calling PC
str saved_psr, [sp, #S_PSR] @ Save CPSR
str r0, [sp, #S_OLD_R0] @ Save OLD_R0
#endif
zero_fp
@ -163,11 +165,11 @@ ENTRY(vector_swi)
* value to determine if it is an EABI or an old ABI call.
*/
#ifdef CONFIG_ARM_THUMB
tst r8, #PSR_T_BIT
tst saved_psr, #PSR_T_BIT
movne r10, #0 @ no thumb OABI emulation
USER( ldreq r10, [lr, #-4] ) @ get SWI instruction
USER( ldreq r10, [saved_pc, #-4] ) @ get SWI instruction
#else
USER( ldr r10, [lr, #-4] ) @ get SWI instruction
USER( ldr r10, [saved_pc, #-4] ) @ get SWI instruction
#endif
ARM_BE8(rev r10, r10) @ little endian instruction
@ -178,15 +180,17 @@ ENTRY(vector_swi)
*/
#elif defined(CONFIG_ARM_THUMB)
/* Legacy ABI only, possibly thumb mode. */
tst r8, #PSR_T_BIT @ this is SPSR from save_user_regs
tst saved_psr, #PSR_T_BIT @ this is SPSR from save_user_regs
addne scno, r7, #__NR_SYSCALL_BASE @ put OS number in
USER( ldreq scno, [lr, #-4] )
USER( ldreq scno, [saved_pc, #-4] )
#else
/* Legacy ABI only. */
USER( ldr scno, [lr, #-4] ) @ get SWI instruction
USER( ldr scno, [saved_pc, #-4] ) @ get SWI instruction
#endif
/* saved_psr and saved_pc are now dead */
uaccess_disable tbl
adr tbl, sys_call_table @ load syscall table pointer
@ -234,7 +238,7 @@ local_restart:
* current task.
*/
9001:
sub lr, lr, #4
sub lr, saved_pc, #4
str lr, [sp, #S_PC]
b ret_fast_syscall
#endif