ARM: 8914/1: NOMMU: Fix exc_ret for XIP

It was reported that 72cd4064fcca "NOMMU: Toggle only bits in
EXC_RETURN we are really care of" breaks NOMMU+XIP combination.
It happens because saved EXC_RETURN gets overwritten when data
section is relocated.

The fix is to propagate EXC_RETURN via register and let relocation
code to commit that value into memory.

Fixes: 72cd4064fcca ("ARM: 8830/1: NOMMU: Toggle only bits in EXC_RETURN we are really care of")
Reported-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Tested-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

diff --git a/arch/arm/kernel/head-common.S b/arch/arm/kernel/head-common.S
index a7810be..4a39828 100644 (file)
--- a/arch/arm/kernel/head-common.S
+++ b/arch/arm/kernel/head-common.S
@@ -68,7 +68,7 @@ ENDPROC(__vet_atags)
  * The following fragment of code is executed with the MMU on in MMU mode,
  * and uses absolute addresses; this is not position independent.
  *
- *  r0  = cp#15 control register
+ *  r0  = cp#15 control register (exc_ret for M-class)
  *  r1  = machine ID
  *  r2  = atags/dtb pointer
  *  r9  = processor ID
@@ -137,7 +137,8 @@ __mmap_switched_data:
 #ifdef CONFIG_CPU_CP15
        .long   cr_alignment                    @ r3
 #else
-       .long   0                               @ r3
+M_CLASS(.long  exc_ret)                        @ r3
+AR_CLASS(.long 0)                              @ r3
 #endif
        .size   __mmap_switched_data, . - __mmap_switched_data
 

diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S
index afa350f..0fc814b 100644 (file)
--- a/arch/arm/kernel/head-nommu.S
+++ b/arch/arm/kernel/head-nommu.S
@@ -201,6 +201,8 @@ M_CLASS(streq       r3, [r12, #PMSAv8_MAIR1])
        bic     r0, r0, #V7M_SCB_CCR_IC
 #endif
        str     r0, [r12, V7M_SCB_CCR]
+       /* Pass exc_ret to __mmap_switched */
+       mov     r0, r10
 #endif /* CONFIG_CPU_CP15 elif CONFIG_CPU_V7M */
        ret     lr
 ENDPROC(__after_proc_init)

diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S
index 1448f14..efebf41 100644 (file)
--- a/arch/arm/mm/proc-v7m.S
+++ b/arch/arm/mm/proc-v7m.S
@@ -136,9 +136,8 @@ __v7m_setup_cont:
        cpsie   i
        svc     #0
 1:     cpsid   i
-       ldr     r0, =exc_ret
-       orr     lr, lr, #EXC_RET_THREADMODE_PROCESSSTACK
-       str     lr, [r0]
+       /* Calculate exc_ret */
+       orr     r10, lr, #EXC_RET_THREADMODE_PROCESSSTACK
        ldmia   sp, {r0-r3, r12}
        str     r5, [r12, #11 * 4]      @ restore the original SVC vector entry
        mov     lr, r6                  @ restore LR