powerpc/fsl_booke: Update of TLBCAMs after init

After init, set readonly memory as ROX and set readwrite
memory as RWX, if STRICT_KERNEL_RWX is enabled.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/66bef0b9c273e1121706883f3cf5ad0a053d863f.1634292136.git.christophe.leroy@csgroup.eu

arch/powerpc/mm/mmu_decl.h

@@ -168,7 +168,7 @@ static inline phys_addr_t v_block_mapped(unsigned long va) { return 0; }
 static inline unsigned long p_block_mapped(phys_addr_t pa) { return 0; }
 #endif
 
-#if defined(CONFIG_PPC_BOOK3S_32) || defined(CONFIG_PPC_8xx)
+#if defined(CONFIG_PPC_BOOK3S_32) || defined(CONFIG_PPC_8xx) || defined(CONFIG_PPC_FSL_BOOK3E)
 void mmu_mark_initmem_nx(void);
 void mmu_mark_rodata_ro(void);
 #else

arch/powerpc/mm/nohash/fsl_book3e.c

@@ -181,7 +181,7 @@ static unsigned long map_mem_in_cams_addr(phys_addr_t phys, unsigned long virt,
 	/* Calculate CAM values */
 	for (i = 0; boundary && i < max_cam_idx; i++) {
 		unsigned long cam_sz;
-		pgprot_t prot = PAGE_KERNEL_X;
+		pgprot_t prot = init ? PAGE_KERNEL_X : PAGE_KERNEL_ROX;
 
 		cam_sz = calc_cam_sz(boundary, virt, phys);
 		if (!dryrun)
@@ -194,7 +194,7 @@ static unsigned long map_mem_in_cams_addr(phys_addr_t phys, unsigned long virt,
 	}
 	for (ram -= amount_mapped; ram && i < max_cam_idx; i++) {
 		unsigned long cam_sz;
-		pgprot_t prot = PAGE_KERNEL_X;
+		pgprot_t prot = init ? PAGE_KERNEL_X : PAGE_KERNEL;
 
 		cam_sz = calc_cam_sz(ram, virt, phys);
 		if (!dryrun)
@@ -209,8 +209,13 @@ static unsigned long map_mem_in_cams_addr(phys_addr_t phys, unsigned long virt,
 	if (dryrun)
 		return amount_mapped;
 
+	if (init) {
 		loadcam_multi(0, i, max_cam_idx);
 		tlbcam_index = i;
+	} else {
+		loadcam_multi(0, i, 0);
+		WARN_ON(i > tlbcam_index);
+	}
 
 #ifdef CONFIG_PPC64
 	get_paca()->tcd.esel_next = i;
@@ -279,6 +284,25 @@ void __init adjust_total_lowmem(void)
 	memblock_set_current_limit(memstart_addr + __max_low_memory);
 }
 
+#ifdef CONFIG_STRICT_KERNEL_RWX
+void mmu_mark_rodata_ro(void)
+{
+	/* Everything is done in mmu_mark_initmem_nx() */
+}
+#endif
+
+void mmu_mark_initmem_nx(void)
+{
+	unsigned long remapped;
+
+	if (!strict_kernel_rwx_enabled())
+		return;
+
+	remapped = map_mem_in_cams(__max_low_memory, CONFIG_LOWMEM_CAM_NUM, false, false);
+
+	WARN_ON(__max_low_memory != remapped);
+}
+
 void setup_initial_memory_limit(phys_addr_t first_memblock_base,
 				phys_addr_t first_memblock_size)
 {