powerpc/32s: Fix segments setup when TASK_SIZE is not a multiple of 256M

For book3s/32 it is assumed that TASK_SIZE is a multiple of 256 Mbytes,
but Kconfig allows any value for TASK_SIZE.

In all relevant calculations, align TASK_SIZE to the upper 256 Mbytes
boundary.

Also use ASM_CONST() in the definition of TASK_SIZE to ensure it is
seen as an unsigned constant.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/8928d906079e156c59794c41e826a684eaaaebb4.1766574657.git.chleroy@kernel.org

Author: chleroy

arch/powerpc/include/asm/book3s/32/mmu-hash.h

@@ -192,12 +192,15 @@ extern s32 patch__hash_page_B, patch__hash_page_C;
 extern s32 patch__flush_hash_A0, patch__flush_hash_A1, patch__flush_hash_A2;
 extern s32 patch__flush_hash_B;
 
+#include <linux/sizes.h>
+#include <linux/align.h>
+
 #include <asm/reg.h>
 #include <asm/task_size_32.h>
 
 static __always_inline void update_user_segment(u32 n, u32 val)
 {
-	if (n << 28 < TASK_SIZE)
+	if (n << 28 < ALIGN(TASK_SIZE, SZ_256M))
 		mtsr(val + n * 0x111, n << 28);
 }
 

arch/powerpc/include/asm/task_size_32.h

@@ -6,7 +6,7 @@
 #error User TASK_SIZE overlaps with KERNEL_START address
 #endif
 
-#define TASK_SIZE (CONFIG_TASK_SIZE)
+#define TASK_SIZE ASM_CONST(CONFIG_TASK_SIZE)
 
 /*
  * This decides where the kernel will search for a free chunk of vm space during

arch/powerpc/kernel/asm-offsets.c

@@ -331,7 +331,7 @@ int main(void)
 
 #ifndef CONFIG_PPC64
 	DEFINE(TASK_SIZE, TASK_SIZE);
-	DEFINE(NUM_USER_SEGMENTS, TASK_SIZE>>28);
+	DEFINE(NUM_USER_SEGMENTS, ALIGN(TASK_SIZE, SZ_256M) >> 28);
 #endif /* ! CONFIG_PPC64 */
 
 	/* datapage offsets for use by vdso */

arch/powerpc/kernel/head_book3s_32.S

@@ -420,7 +420,7 @@ InstructionTLBMiss:
 	lwz	r2,0(r2)		/* get pmd entry */
 #ifdef CONFIG_EXECMEM
 	rlwinm	r3, r0, 4, 0xf
-	subi	r3, r3, (TASK_SIZE >> 28) & 0xf
+	subi	r3, r3, NUM_USER_SEGMENTS
 #endif
 	rlwinm.	r2,r2,0,0,19		/* extract address of pte page */
 	beq-	InstructionAddressInvalid	/* return if no mapping */
@@ -475,7 +475,7 @@ DataLoadTLBMiss:
 	lwz	r2,0(r1)		/* get pmd entry */
 	rlwinm	r3, r0, 4, 0xf
 	rlwinm.	r2,r2,0,0,19		/* extract address of pte page */
-	subi	r3, r3, (TASK_SIZE >> 28) & 0xf
+	subi	r3, r3, NUM_USER_SEGMENTS
 	beq-	2f			/* bail if no mapping */
 1:	rlwimi	r2,r0,22,20,29		/* insert next 10 bits of address */
 	lwz	r2,0(r2)		/* get linux-style pte */
@@ -554,7 +554,7 @@ DataStoreTLBMiss:
 	lwz	r2,0(r1)		/* get pmd entry */
 	rlwinm	r3, r0, 4, 0xf
 	rlwinm.	r2,r2,0,0,19		/* extract address of pte page */
-	subi	r3, r3, (TASK_SIZE >> 28) & 0xf
+	subi	r3, r3, NUM_USER_SEGMENTS
 	beq-	2f			/* bail if no mapping */
 1:
 	rlwimi	r2,r0,22,20,29		/* insert next 10 bits of address */

arch/powerpc/mm/book3s32/mmu.c

@@ -225,7 +225,7 @@ int mmu_mark_initmem_nx(void)
 
 	BUILD_BUG_ON(ALIGN_DOWN(MODULES_VADDR, SZ_256M) < TASK_SIZE);
 
-	for (i = TASK_SIZE >> 28; i < 16; i++) {
+	for (i = ALIGN(TASK_SIZE, SZ_256M) >> 28; i < 16; i++) {
 		/* Do not set NX on VM space for modules */
 		if (is_module_segment(i << 28))
 			continue;

arch/powerpc/mm/ptdump/segment_regs.c

@@ -31,7 +31,7 @@ static int sr_show(struct seq_file *m, void *v)
 	int i;
 
 	seq_puts(m, "---[ User Segments ]---\n");
-	for (i = 0; i < TASK_SIZE >> 28; i++)
+	for (i = 0; i < ALIGN(TASK_SIZE, SZ_256M) >> 28; i++)
 		seg_show(m, i);
 
 	seq_puts(m, "\n---[ Kernel Segments ]---\n");