@@ -42,6 +42,8 @@
#define vectors_high() (0)
#endif
+#ifdef CONFIG_CPU_CP15
+
extern unsigned long cr_no_alignment; /* defined in entry-armv.S */
extern unsigned long cr_alignment; /* defined in entry-armv.S */
@@ -82,6 +84,13 @@ static inline void set_copro_access(unsigned int val)
isb();
}
-#endif
+#else /* ifdef CONFIG_CPU_CP15 */
+
+#define cr_no_alignment UL(0)
+#define cr_alignment UL(0)
+
+#endif /* ifdef CONFIG_CPU_CP15 / else */
+
+#endif /* ifndef __ASSEMBLY__ */
#endif
@@ -98,8 +98,9 @@ __mmap_switched:
str r9, [r4] @ Save processor ID
str r1, [r5] @ Save machine type
str r2, [r6] @ Save atags pointer
- bic r4, r0, #CR_A @ Clear 'A' bit
- stmia r7, {r0, r4} @ Save control register values
+ cmp r7, #0
+ bicne r4, r0, #CR_A @ Clear 'A' bit
+ stmneia r7, {r0, r4} @ Save control register values
b start_kernel
ENDPROC(__mmap_switched)
@@ -113,7 +114,11 @@ __mmap_switched_data:
.long processor_id @ r4
.long __machine_arch_type @ r5
.long __atags_pointer @ r6
+#ifdef CONFIG_CPU_CP15
.long cr_alignment @ r7
+#else
+ .long 0
+#endif
.long init_thread_union + THREAD_START_SP @ sp
.size __mmap_switched_data, . - __mmap_switched_data
@@ -962,12 +962,14 @@ static int __init alignment_init(void)
return -ENOMEM;
#endif
+#ifdef CONFIG_CPU_CP15
if (cpu_is_v6_unaligned()) {
cr_alignment &= ~CR_A;
cr_no_alignment &= ~CR_A;
set_cr(cr_alignment);
ai_usermode = safe_usermode(ai_usermode, false);
}
+#endif
hook_fault_code(FAULT_CODE_ALIGNMENT, do_alignment, SIGBUS, BUS_ADRALN,
"alignment exception");
@@ -96,6 +96,7 @@ static struct cachepolicy cache_policies[] __initdata = {
}
};
+#ifdef CONFIG_CPU_CP15
/*
* These are useful for identifying cache coherency
* problems by allowing the cache or the cache and
@@ -194,6 +195,22 @@ void adjust_cr(unsigned long mask, unsigned long set)
}
#endif
+#else
+
+static int __init early_cachepolicy(char *p)
+{
+ pr_warning("cachepolicy kernel parameter not supported without cp15\n");
+}
+early_param("cachepolicy", early_cachepolicy);
+
+static int __init noalign_setup(char *__unused)
+{
+ pr_warning("noalign kernel parameter not supported without cp15\n");
+}
+__setup("noalign", noalign_setup);
+
+#endif
+
#define PROT_PTE_DEVICE L_PTE_PRESENT|L_PTE_YOUNG|L_PTE_DIRTY|L_PTE_XN
#define PROT_SECT_DEVICE PMD_TYPE_SECT|PMD_SECT_AP_WRITE
This makes cr_alignment a constant 0 to break code that tries to modify the value as it's likely that it's built on wrong assumption when CONFIG_CPU_CP15 isn't defined. For code that is only reading the value 0 is more or less a fine value to report. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- Hello, in the v3 series this patch was titled "ARM: protect usage of cr_alignment by #ifdef CONFIG_CPU_CP15". In response to Nicolas' review cr_alignment was made a #define and only the code modifying it was patched. Moreover I patched the cachepolicy and noalign kernel parameter handling to just print a warning that these are unimplemented without cp15. Best regards Uwe arch/arm/include/asm/cp15.h | 11 ++++++++++- arch/arm/kernel/head-common.S | 9 +++++++-- arch/arm/mm/alignment.c | 2 ++ arch/arm/mm/mmu.c | 17 +++++++++++++++++ 4 files changed, 36 insertions(+), 3 deletions(-)