2 files changed, 139 insertions, 3 deletions

diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h
index 3f881548fb61..0e29ccf903d0 100644
--- a/arch/powerpc/include/asm/code-patching.h
+++ b/arch/powerpc/include/asm/code-patching.h
@@ -74,6 +74,7 @@ int create_cond_branch(ppc_inst_t *instr, const u32 *addr,
 int patch_branch(u32 *addr, unsigned long target, int flags);
 int patch_instruction(u32 *addr, ppc_inst_t instr);
 int raw_patch_instruction(u32 *addr, ppc_inst_t instr);
+int patch_instructions(u32 *addr, u32 *code, size_t len, bool repeat_instr);
 
 static inline unsigned long patch_site_addr(s32 *site)
 {
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 7a47a871e6b8..c6ab46156cda 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -205,9 +205,6 @@ void __init poking_init(void)
 {
 	int ret;
 
-	if (!IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
-		return;
-
 	if (mm_patch_enabled())
 		ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
 					"powerpc/text_poke_mm:online",
@@ -375,6 +372,144 @@ int patch_instruction(u32 *addr, ppc_inst_t instr)
 }
 NOKPROBE_SYMBOL(patch_instruction);
 
+static int __patch_instructions(u32 *patch_addr, u32 *code, size_t len, bool repeat_instr)
+{
+	unsigned long start = (unsigned long)patch_addr;
+
+	/* Repeat instruction */
+	if (repeat_instr) {
+		ppc_inst_t instr = ppc_inst_read(code);
+
+		if (ppc_inst_prefixed(instr)) {
+			u64 val = ppc_inst_as_ulong(instr);
+
+			memset64((u64 *)patch_addr, val, len / 8);
+		} else {
+			u32 val = ppc_inst_val(instr);
+
+			memset32(patch_addr, val, len / 4);
+		}
+	} else {
+		memcpy(patch_addr, code, len);
+	}
+
+	smp_wmb();	/* smp write barrier */
+	flush_icache_range(start, start + len);
+	return 0;
+}
+
+/*
+ * A page is mapped and instructions that fit the page are patched.
+ * Assumes 'len' to be (PAGE_SIZE - offset_in_page(addr)) or below.
+ */
+static int __do_patch_instructions_mm(u32 *addr, u32 *code, size_t len, bool repeat_instr)
+{
+	struct mm_struct *patching_mm, *orig_mm;
+	unsigned long pfn = get_patch_pfn(addr);
+	unsigned long text_poke_addr;
+	spinlock_t *ptl;
+	u32 *patch_addr;
+	pte_t *pte;
+	int err;
+
+	patching_mm = __this_cpu_read(cpu_patching_context.mm);
+	text_poke_addr = __this_cpu_read(cpu_patching_context.addr);
+	patch_addr = (u32 *)(text_poke_addr + offset_in_page(addr));
+
+	pte = get_locked_pte(patching_mm, text_poke_addr, &ptl);
+	if (!pte)
+		return -ENOMEM;
+
+	__set_pte_at(patching_mm, text_poke_addr, pte, pfn_pte(pfn, PAGE_KERNEL), 0);
+
+	/* order PTE update before use, also serves as the hwsync */
+	asm volatile("ptesync" ::: "memory");
+
+	/* order context switch after arbitrary prior code */
+	isync();
+
+	orig_mm = start_using_temp_mm(patching_mm);
+
+	err = __patch_instructions(patch_addr, code, len, repeat_instr);
+
+	/* context synchronisation performed by __patch_instructions */
+	stop_using_temp_mm(patching_mm, orig_mm);
+
+	pte_clear(patching_mm, text_poke_addr, pte);
+	/*
+	 * ptesync to order PTE update before TLB invalidation done
+	 * by radix__local_flush_tlb_page_psize (in _tlbiel_va)
+	 */
+	local_flush_tlb_page_psize(patching_mm, text_poke_addr, mmu_virtual_psize);
+
+	pte_unmap_unlock(pte, ptl);
+
+	return err;
+}
+
+/*
+ * A page is mapped and instructions that fit the page are patched.
+ * Assumes 'len' to be (PAGE_SIZE - offset_in_page(addr)) or below.
+ */
+static int __do_patch_instructions(u32 *addr, u32 *code, size_t len, bool repeat_instr)
+{
+	unsigned long pfn = get_patch_pfn(addr);
+	unsigned long text_poke_addr;
+	u32 *patch_addr;
+	pte_t *pte;
+	int err;
+
+	text_poke_addr = (unsigned long)__this_cpu_read(cpu_patching_context.addr) & PAGE_MASK;
+	patch_addr = (u32 *)(text_poke_addr + offset_in_page(addr));
+
+	pte = __this_cpu_read(cpu_patching_context.pte);
+	__set_pte_at(&init_mm, text_poke_addr, pte, pfn_pte(pfn, PAGE_KERNEL), 0);
+	/* See ptesync comment in radix__set_pte_at() */
+	if (radix_enabled())
+		asm volatile("ptesync" ::: "memory");
+
+	err = __patch_instructions(patch_addr, code, len, repeat_instr);
+
+	pte_clear(&init_mm, text_poke_addr, pte);
+	flush_tlb_kernel_range(text_poke_addr, text_poke_addr + PAGE_SIZE);
+
+	return err;
+}
+
+/*
+ * Patch 'addr' with 'len' bytes of instructions from 'code'.
+ *
+ * If repeat_instr is true, the same instruction is filled for
+ * 'len' bytes.
+ */
+int patch_instructions(u32 *addr, u32 *code, size_t len, bool repeat_instr)
+{
+	while (len > 0) {
+		unsigned long flags;
+		size_t plen;
+		int err;
+
+		plen = min_t(size_t, PAGE_SIZE - offset_in_page(addr), len);
+
+		local_irq_save(flags);
+		if (mm_patch_enabled())
+			err = __do_patch_instructions_mm(addr, code, plen, repeat_instr);
+		else
+			err = __do_patch_instructions(addr, code, plen, repeat_instr);
+		local_irq_restore(flags);
+		if (err)
+			return err;
+
+		len -= plen;
+		addr = (u32 *)((unsigned long)addr + plen);
+		if (!repeat_instr)
+			code = (u32 *)((unsigned long)code + plen);
+	}
+
+	return 0;
+}
+NOKPROBE_SYMBOL(patch_instructions);
+
 int patch_branch(u32 *addr, unsigned long target, int flags)
 {
 	ppc_inst_t instr;