powerpc/32s: Define a MODULE area below kernel text all the time

On book3s/32, the segment below kernel text is used for module
allocation when CONFIG_STRICT_KERNEL_RWX is defined.

In order to benefit from the powerpc specific module_alloc()
function which allocate modules with 32 Mbytes from
end of kernel text, use that segment below PAGE_OFFSET at all time.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a46dcdd39a9e80b012d86c294c4e5cd8d31665f3.1617283827.git.christophe.leroy@csgroup.eu

arch/powerpc/Kconfig

@@ -1220,7 +1220,7 @@ config TASK_SIZE_BOOL
 config TASK_SIZE
 	hex "Size of user task space" if TASK_SIZE_BOOL
 	default "0x80000000" if PPC_8xx
-	default "0xb0000000" if PPC_BOOK3S_32 && STRICT_KERNEL_RWX
+	default "0xb0000000" if PPC_BOOK3S_32
 	default "0xc0000000"
 endmenu
 

arch/powerpc/include/asm/book3s/32/pgtable.h

@@ -194,10 +194,8 @@ int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
 #define VMALLOC_END	ioremap_bot
 #endif
 
-#ifdef CONFIG_STRICT_KERNEL_RWX
 #define MODULES_END	ALIGN_DOWN(PAGE_OFFSET, SZ_256M)
 #define MODULES_VADDR	(MODULES_END - SZ_256M)
-#endif
 
 #ifndef __ASSEMBLY__
 #include <linux/sched.h>

arch/powerpc/mm/book3s32/mmu.c

@@ -184,17 +184,10 @@ static bool is_module_segment(unsigned long addr)
 {
 	if (!IS_ENABLED(CONFIG_MODULES))
 		return false;
-#ifdef MODULES_VADDR
 	if (addr < ALIGN_DOWN(MODULES_VADDR, SZ_256M))
 		return false;
 	if (addr > ALIGN(MODULES_END, SZ_256M) - 1)
 		return false;
-#else
-	if (addr < ALIGN_DOWN(VMALLOC_START, SZ_256M))
-		return false;
-	if (addr > ALIGN(VMALLOC_END, SZ_256M) - 1)
-		return false;
-#endif
 	return true;
 }