[PATCH v2 0/9] Enable STRICT_KERNEL_RWX

Enable STRICT_KERNEL_RWX for PPC64/BOOK3S

These patches enable RX mappings of kernel text.
rodata is mapped RX as well as a trade-off, there
are more details in the patch description

As a prerequisite for R/O text, patch_instruction
is moved over to using a separate mapping that
allows write to kernel text. xmon/ftrace/kprobes
have been moved over to work with patch_instruction

There are a few bug fixes, the updatepp and updateboltedpp
did not use flags as described in PAPR and the ptdump
utility ignored the first PFN

TODOs:
	1. Radix support
	2. 32 bit support

For Radix support, it should be simple, we need to revisit
the way linear mapping is done for text, avoid any 1G
maps to make sure we use 2M and then protect at that
granularity. I will send a follow-up patch to this series
adding radix support

There are patches for 32 bit support from Christophe Leroy
at http://patchwork.ozlabs.org/patch/768257/. The patches
for map_page to map_kernel_page are a pre-requisite.
Another build failure was reported, because instead
of using ARCH_HAS_SET_MEMORY as a gate for set_memory.h
inclusion, some of the infrastructure in the core kernel
uses CONFIG_STRICT_KERNEL_RWX.


Balbir Singh (9):
  powerpc/lib/code-patching: Enhance code patching
  powerpc/kprobes: Move kprobes over to patch_instruction
  powerpc/kprobes/optprobes: Move over to patch_instruction
  powerpc/xmon: Add patch_instruction supporf for xmon
  powerpc/vmlinux.lds: Align __init_begin to 16M
  powerpc/platform/pseries/lpar: Fix updatepp and updateboltedpp
  powerpc/mm/hash: Implement mark_rodata_ro() for hash
  powerpc/Kconfig: Enable STRICT_KERNEL_RWX
  powerpc/mm/ptdump: Dump the first entry of the linear mapping as well

 arch/powerpc/Kconfig                       |   1 +
 arch/powerpc/include/asm/book3s/64/hash.h  |   3 +
 arch/powerpc/include/asm/book3s/64/radix.h |   4 +
 arch/powerpc/kernel/kprobes.c              |   4 +-
 arch/powerpc/kernel/optprobes.c            |  58 ++++++++-----
 arch/powerpc/kernel/vmlinux.lds.S          |  10 ++-
 arch/powerpc/lib/code-patching.c           | 127 ++++++++++++++++++++++++++++-
 arch/powerpc/mm/dump_hashpagetable.c       |   2 +-
 arch/powerpc/mm/pgtable-hash64.c           |  35 ++++++++
 arch/powerpc/mm/pgtable-radix.c            |   7 ++
 arch/powerpc/mm/pgtable_64.c               |   9 ++
 arch/powerpc/platforms/pseries/lpar.c      |  13 ++-
 arch/powerpc/xmon/xmon.c                   |   7 +-
 13 files changed, 246 insertions(+), 34 deletions(-)

-- 
2.9.3

Today our patching happens via direct copy and
patch_instruction. The patching code is well
contained in the sense that copying bits are limited.

While considering implementation of CONFIG_STRICT_RWX,
the first requirement is to a create another mapping
that will allow for patching. We create the window using
text_poke_area, allocated via get_vm_area(), which might
be an overkill. text_poke_area is per CPU to avoid locking
Other arches do similar things, but use fixmaps. The reason
for not using fixmaps is to make use of any randomization in
the future. The code also relies on set_pte_at and pte_clear
to do the appropriate tlb flushing.

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/lib/code-patching.c | 137 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 133 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 500b0f6..eb26b16 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c

@@ -12,23 +12,151 @@
 #include <linux/vmalloc.h>
 #include <linux/init.h>
 #include <linux/mm.h>
+#include <linux/cpuhotplug.h>
 #include <asm/page.h>
 #include <asm/code-patching.h>
 #include <linux/uaccess.h>
 #include <linux/kprobes.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
 
+static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
+static unsigned int text_area_patch_avail;
 
-int patch_instruction(unsigned int *addr, unsigned int instr)
+static int text_area_cpu_up(unsigned int cpu)
+{
+	struct vm_struct *area;
+
+	area = get_vm_area(PAGE_SIZE, VM_ALLOC);
+	if (!area) {
+		WARN_ONCE(1, "Failed to create text area for cpu %d\n",
+			cpu);
+		return -1;
+	}
+	this_cpu_write(text_poke_area, area);
+	return 0;
+}
+
+static int text_area_cpu_down(unsigned int cpu)
+{
+	free_vm_area(this_cpu_read(text_poke_area));
+	return 0;
+}
+
+/*
+ * This is an early_initcall and early_initcalls happen at the right time
+ * for us, after slab is enabled and before we mark ro pages R/O. In the
+ * future if get_vm_area is randomized, this will be more flexible than
+ * fixmap
+ */
+static int __init setup_text_poke_area(void)
 {
+	struct vm_struct *area;
+	int cpu;
+
+	for_each_online_cpu(cpu) {
+		area = get_vm_area(PAGE_SIZE, VM_ALLOC);
+		if (!area) {
+			WARN_ONCE(1, "Failed to create text area for cpu %d\n",
+				cpu);
+			/* Should we disable strict rwx? */
+			continue;
+		}
+		this_cpu_write(text_poke_area, area);
+	}
+	cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
+		"powerpc/text_poke:online", text_area_cpu_up,
+		text_area_cpu_down);
+	text_area_patch_avail = 1;
+	/*
+	 * The barrier here ensures the write is visible to
+	 * patch_instruction()
+	 */
+	smp_wmb();
+	pr_info("text_poke area ready...\n");
+	return 0;
+}
+
+/*
+ * This can be called for kernel text or a module.
+ */
+static int kernel_map_addr(void *addr)
+{
+	unsigned long pfn;
 	int err;
 
-	__put_user_size(instr, addr, 4, err);
+	if (is_vmalloc_addr(addr))
+		pfn = vmalloc_to_pfn(addr);
+	else
+		pfn = __pa_symbol(addr) >> PAGE_SHIFT;
+
+	err = map_kernel_page(
+			(unsigned long)__this_cpu_read(text_poke_area)->addr,
+			(pfn << PAGE_SHIFT), _PAGE_KERNEL_RW | _PAGE_PRESENT);
+	pr_devel("Mapped addr %p with pfn %lx\n",
+			__this_cpu_read(text_poke_area)->addr, pfn);
 	if (err)
-		return err;
-	asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" : : "r" (addr));
+		return -1;
 	return 0;
 }
 
+static inline void kernel_unmap_addr(void *addr)
+{
+	pte_t *pte;
+	unsigned long kaddr = (unsigned long)addr;
+
+	pte = pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(kaddr),
+				kaddr), kaddr), kaddr);
+	pr_devel("clearing mm %p, pte %p, kaddr %lx\n", &init_mm, pte, kaddr);
+	pte_clear(&init_mm, kaddr, pte);
+	flush_tlb_kernel_range(kaddr, kaddr + PAGE_SIZE);
+}
+
+int patch_instruction(unsigned int *addr, unsigned int instr)
+{
+	int err;
+	unsigned int *dest = NULL;
+	unsigned long flags;
+	unsigned long kaddr = (unsigned long)addr;
+
+	/*
+	 * Make sure we can see any write of text_area_patch_avail
+	 */
+	smp_rmb();
+
+	/*
+	 * During early early boot patch_instruction is called
+	 * when text_poke_area is not ready, but we still need
+	 * to allow patching. We just do the plain old patching
+	 * We use text_area_patch_avail, since per cpu read
+	 * via __this_cpu_read of text_poke_area might not
+	 * yet be available.
+	 * TODO: Make text_area_patch_avail per cpu?
+	 */
+	if (!text_area_patch_avail) {
+		__put_user_size(instr, addr, 4, err);
+		asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" :: "r" (addr));
+		return 0;
+	}
+
+	local_irq_save(flags);
+	if (kernel_map_addr(addr)) {
+		err = -1;
+		goto out;
+	}
+
+	dest = (unsigned int *)(__this_cpu_read(text_poke_area)->addr) +
+		((kaddr & ~PAGE_MASK) / sizeof(unsigned int));
+	__put_user_size(instr, dest, 4, err);
+	asm ("dcbst 0, %0; sync; icbi 0,%0; icbi 0,%1; sync; isync"
+		::"r" (dest), "r"(addr));
+	kernel_unmap_addr(__this_cpu_read(text_poke_area)->addr);
+out:
+	local_irq_restore(flags);
+	return err;
+}
+NOKPROBE_SYMBOL(patch_instruction);
+
 int patch_branch(unsigned int *addr, unsigned long target, int flags)
 {
 	return patch_instruction(addr, create_branch(addr, target, flags));

@@ -514,3 +642,4 @@ static int __init test_code_patching(void)
 late_initcall(test_code_patching);
 
 #endif /* CONFIG_CODE_PATCHING_SELFTEST */
+early_initcall(setup_text_poke_area);

-- 
2.9.3

arch_arm/disarm_probe use direct assignment for copying
instructions, replace them with patch_instruction

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/kernel/kprobes.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index fc43435..b49f8f0 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c

@@ -158,7 +158,7 @@ NOKPROBE_SYMBOL(arch_prepare_kprobe);
 
 void arch_arm_kprobe(struct kprobe *p)
 {
-	*p->addr = BREAKPOINT_INSTRUCTION;
+	patch_instruction(p->addr, BREAKPOINT_INSTRUCTION);
 	flush_icache_range((unsigned long) p->addr,
 			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
 }

@@ -166,7 +166,7 @@ NOKPROBE_SYMBOL(arch_arm_kprobe);
 
 void arch_disarm_kprobe(struct kprobe *p)
 {
-	*p->addr = p->opcode;
+	patch_instruction(p->addr, p->opcode);
 	flush_icache_range((unsigned long) p->addr,
 			   (unsigned long) p->addr + sizeof(kprobe_opcode_t));
 }

-- 
2.9.3

With text moving to read-only migrate optprobes to using
the patch_instruction infrastructure. Without this optprobes
will fail and complain.

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/kernel/optprobes.c | 58 ++++++++++++++++++++++++++---------------
 1 file changed, 37 insertions(+), 21 deletions(-)

diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
index ec60ed0..1c7326c 100644
--- a/arch/powerpc/kernel/optprobes.c
+++ b/arch/powerpc/kernel/optprobes.c

@@ -158,12 +158,13 @@ void arch_remove_optimized_kprobe(struct optimized_kprobe *op)
 void patch_imm32_load_insns(unsigned int val, kprobe_opcode_t *addr)
 {
 	/* addis r4,0,(insn)@h */
-	*addr++ = PPC_INST_ADDIS | ___PPC_RT(4) |
-		  ((val >> 16) & 0xffff);
+	patch_instruction((unsigned int *)addr, PPC_INST_ADDIS | ___PPC_RT(4) |
+					((val >> 16) & 0xffff));
+	addr++;
 
 	/* ori r4,r4,(insn)@l */
-	*addr = PPC_INST_ORI | ___PPC_RA(4) | ___PPC_RS(4) |
-		(val & 0xffff);
+	patch_instruction((unsigned int *)addr, PPC_INST_ORI | ___PPC_RA(4) |
+					___PPC_RS(4) | (val & 0xffff));
 }
 
 /*

@@ -173,24 +174,28 @@ void patch_imm32_load_insns(unsigned int val, kprobe_opcode_t *addr)
 void patch_imm64_load_insns(unsigned long val, kprobe_opcode_t *addr)
 {
 	/* lis r3,(op)@highest */
-	*addr++ = PPC_INST_ADDIS | ___PPC_RT(3) |
-		  ((val >> 48) & 0xffff);
+	patch_instruction((unsigned int *)addr, PPC_INST_ADDIS | ___PPC_RT(3) |
+					((val >> 48) & 0xffff));
+	addr++;
 
 	/* ori r3,r3,(op)@higher */
-	*addr++ = PPC_INST_ORI | ___PPC_RA(3) | ___PPC_RS(3) |
-		  ((val >> 32) & 0xffff);
+	patch_instruction((unsigned int *)addr, PPC_INST_ORI | ___PPC_RA(3) |
+				___PPC_RS(3) | ((val >> 32) & 0xffff));
+	addr++;
 
 	/* rldicr r3,r3,32,31 */
-	*addr++ = PPC_INST_RLDICR | ___PPC_RA(3) | ___PPC_RS(3) |
-		  __PPC_SH64(32) | __PPC_ME64(31);
+	patch_instruction((unsigned int *)addr, PPC_INST_RLDICR | ___PPC_RA(3) |
+				___PPC_RS(3) | __PPC_SH64(32) | __PPC_ME64(31));
+	addr++;
 
 	/* oris r3,r3,(op)@h */
-	*addr++ = PPC_INST_ORIS | ___PPC_RA(3) | ___PPC_RS(3) |
-		  ((val >> 16) & 0xffff);
+	patch_instruction((unsigned int *)addr, PPC_INST_ORIS | ___PPC_RA(3) |
+					___PPC_RS(3) | ((val >> 16) & 0xffff));
+	addr++;
 
 	/* ori r3,r3,(op)@l */
-	*addr = PPC_INST_ORI | ___PPC_RA(3) | ___PPC_RS(3) |
-		(val & 0xffff);
+	patch_instruction((unsigned int *)addr, PPC_INST_ORI | ___PPC_RA(3) |
+				___PPC_RS(3) | (val & 0xffff));
 }
 
 int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)

@@ -198,7 +203,8 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
 	kprobe_opcode_t *buff, branch_op_callback, branch_emulate_step;
 	kprobe_opcode_t *op_callback_addr, *emulate_step_addr;
 	long b_offset;
-	unsigned long nip;
+	unsigned long nip, size;
+	int rc, i;
 
 	kprobe_ppc_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
 

@@ -231,8 +237,15 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
 		goto error;
 
 	/* Setup template */
-	memcpy(buff, optprobe_template_entry,
-			TMPL_END_IDX * sizeof(kprobe_opcode_t));
+	/* We can optimize this via patch_instruction_window later */
+	size = (TMPL_END_IDX * sizeof(kprobe_opcode_t)) / sizeof(int);
+	pr_devel("Copying template to %p, size %lu\n", buff, size);
+	for (i = 0; i < size; i++) {
+		rc = patch_instruction((unsigned int *)buff + i,
+			*((unsigned int *)(optprobe_template_entry) + i));
+		if (rc < 0)
+			goto error;
+	}
 
 	/*
 	 * Fixup the template with instructions to:

@@ -261,8 +274,10 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
 	if (!branch_op_callback || !branch_emulate_step)
 		goto error;
 
-	buff[TMPL_CALL_HDLR_IDX] = branch_op_callback;
-	buff[TMPL_EMULATE_IDX] = branch_emulate_step;
+	patch_instruction((unsigned int *)buff + TMPL_CALL_HDLR_IDX,
+				branch_op_callback);
+	patch_instruction((unsigned int *)buff + TMPL_EMULATE_IDX,
+				branch_emulate_step);
 
 	/*
 	 * 3. load instruction to be emulated into relevant register, and

@@ -272,8 +287,9 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
 	/*
 	 * 4. branch back from trampoline
 	 */
-	buff[TMPL_RET_IDX] = create_branch((unsigned int *)buff + TMPL_RET_IDX,
-				(unsigned long)nip, 0);
+	patch_instruction((unsigned int *)buff + TMPL_RET_IDX,
+				create_branch((unsigned int *)buff +
+				TMPL_RET_IDX, (unsigned long)nip, 0));
 
 	flush_icache_range((unsigned long)buff,
 			   (unsigned long)(&buff[TMPL_END_IDX]));

-- 
2.9.3

Move from mwrite() to patch_instruction() for xmon for
breakpoint addition and removal.

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/xmon/xmon.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index a728e19..08e367e 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c

@@ -53,6 +53,7 @@
 #include <asm/xive.h>
 #include <asm/opal.h>
 #include <asm/firmware.h>
+#include <asm/code-patching.h>
 
 #ifdef CONFIG_PPC64
 #include <asm/hvcall.h>

@@ -837,7 +838,8 @@ static void insert_bpts(void)
 		store_inst(&bp->instr[0]);
 		if (bp->enabled & BP_CIABR)
 			continue;
-		if (mwrite(bp->address, &bpinstr, 4) != 4) {
+		if (patch_instruction((unsigned int *)bp->address,
+							bpinstr) != 0) {
 			printf("Couldn't write instruction at %lx, "
 			       "disabling breakpoint there\n", bp->address);
 			bp->enabled &= ~BP_TRAP;

@@ -874,7 +876,8 @@ static void remove_bpts(void)
 			continue;
 		if (mread(bp->address, &instr, 4) == 4
 		    && instr == bpinstr
-		    && mwrite(bp->address, &bp->instr, 4) != 4)
+		    && patch_instruction(
+			(unsigned int *)bp->address, bp->instr[0]) != 0)
 			printf("Couldn't remove breakpoint at %lx\n",
 			       bp->address);
 		else

-- 
2.9.3

For CONFIG_STRICT_KERNEL_RWX align __init_begin to 16M.
We use 16M since its the larger of 2M on radix and 16M
on hash for our linear mapping. The plan is to have
.text, .rodata and everything upto __init_begin marked
as RX. Note we still have executable read only data.
We could further align read only data to another 16M
boundary, but then the linker starts using stubs and
that breaks our assembler code in head_64.S

We don't use multi PT_LOAD in PHDRS because we are
not sure if all bootloaders support them

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/kernel/vmlinux.lds.S | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index ace6b65..b1a2505 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S

@@ -8,6 +8,12 @@
 #include <asm/cache.h>
 #include <asm/thread_info.h>
 
+#ifdef CONFIG_STRICT_KERNEL_RWX
+#define STRICT_ALIGN_SIZE	(1 << 24)
+#else
+#define STRICT_ALIGN_SIZE	PAGE_SIZE
+#endif
+
 ENTRY(_stext)
 
 PHDRS {

@@ -123,7 +129,7 @@ SECTIONS
 	PROVIDE32 (etext = .);
 
 	/* Read-only data */
-	RODATA
+	RO_DATA(PAGE_SIZE)
 
 	EXCEPTION_TABLE(0)
 

@@ -140,7 +146,7 @@ SECTIONS
 /*
  * Init sections discarded at runtime
  */
-	. = ALIGN(PAGE_SIZE);
+	. = ALIGN(STRICT_ALIGN_SIZE);
 	__init_begin = .;
 	INIT_TEXT_SECTION(PAGE_SIZE) :kernel
 

-- 
2.9.3

PAPR has pp0 in bit 55, currently we assumed that bit
pp0 is bit 0 (all bits in IBM order). This patch fixes
the pp0 bits for both these routines that use H_PROTECT

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/platforms/pseries/lpar.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 6541d0b..83db643 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c

@@ -301,7 +301,7 @@ static long pSeries_lpar_hpte_updatepp(unsigned long slot,
 				       int ssize, unsigned long inv_flags)
 {
 	unsigned long lpar_rc;
-	unsigned long flags = (newpp & 7) | H_AVPN;
+	unsigned long flags;
 	unsigned long want_v;
 
 	want_v = hpte_encode_avpn(vpn, psize, ssize);

@@ -309,6 +309,11 @@ static long pSeries_lpar_hpte_updatepp(unsigned long slot,
 	pr_devel("    update: avpnv=%016lx, hash=%016lx, f=%lx, psize: %d ...",
 		 want_v, slot, flags, psize);
 
+	/*
+	 * Move pp0 and set the mask, pp0 is bit 55
+	 * We ignore the keys for now.
+	 */
+	flags = ((newpp & HPTE_R_PP0) >> 55) | (newpp & 7) | H_AVPN;
 	lpar_rc = plpar_pte_protect(flags, slot, want_v);
 
 	if (lpar_rc == H_NOT_FOUND) {

@@ -379,7 +384,11 @@ static void pSeries_lpar_hpte_updateboltedpp(unsigned long newpp,
 	slot = pSeries_lpar_hpte_find(vpn, psize, ssize);
 	BUG_ON(slot == -1);
 
-	flags = newpp & 7;
+	/*
+	 * Move pp0 and set the mask, pp0 is bit 55
+	 * We ignore the keys for now.
+	 */
+	flags = ((newpp & HPTE_R_PP0) >> 55) | (newpp & 7);
 	lpar_rc = plpar_pte_protect(flags, slot, 0);
 
 	BUG_ON(lpar_rc != H_SUCCESS);

-- 
2.9.3

With hash we update the bolted pte to mark it read-only. We rely
on the MMU_FTR_KERNEL_RO to generate the correct permissions
for read-only text. The radix implementation just prints a warning
in this implementation

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/include/asm/book3s/64/hash.h  |  3 +++
 arch/powerpc/include/asm/book3s/64/radix.h |  4 ++++
 arch/powerpc/mm/pgtable-hash64.c           | 35 ++++++++++++++++++++++++++++++
 arch/powerpc/mm/pgtable-radix.c            |  7 ++++++
 arch/powerpc/mm/pgtable_64.c               |  9 ++++++++
 5 files changed, 58 insertions(+)

diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index 4e957b0..0ce513f 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h

@@ -89,6 +89,9 @@ static inline int hash__pgd_bad(pgd_t pgd)
 {
 	return (pgd_val(pgd) == 0);
 }
+#ifdef CONFIG_STRICT_KERNEL_RWX
+extern void hash__mark_rodata_ro(void);
+#endif
 
 extern void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
 			    pte_t *ptep, unsigned long pte, int huge);

diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
index ac16d19..368cb54 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h

@@ -116,6 +116,10 @@
 #define RADIX_PUD_TABLE_SIZE	(sizeof(pud_t) << RADIX_PUD_INDEX_SIZE)
 #define RADIX_PGD_TABLE_SIZE	(sizeof(pgd_t) << RADIX_PGD_INDEX_SIZE)
 
+#ifdef CONFIG_STRICT_KERNEL_RWX
+extern void radix__mark_rodata_ro(void);
+#endif
+
 static inline unsigned long __radix_pte_update(pte_t *ptep, unsigned long clr,
 					       unsigned long set)
 {

diff --git a/arch/powerpc/mm/pgtable-hash64.c b/arch/powerpc/mm/pgtable-hash64.c
index 8b85a14..dda808b 100644
--- a/arch/powerpc/mm/pgtable-hash64.c
+++ b/arch/powerpc/mm/pgtable-hash64.c

@@ -11,8 +11,12 @@
 
 #include <linux/sched.h>
 #include <linux/mm_types.h>
+#include <linux/mm.h>
 
 #include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+#include <asm/sections.h>
+#include <asm/mmu.h>
 #include <asm/tlb.h>
 
 #include "mmu_decl.h"

@@ -342,3 +346,34 @@ int hash__has_transparent_hugepage(void)
 	return 1;
 }
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
+#ifdef CONFIG_STRICT_KERNEL_RWX
+void hash__mark_rodata_ro(void)
+{
+	unsigned long start = (unsigned long)_stext;
+	unsigned long end = (unsigned long)__init_begin;
+	unsigned long idx;
+	unsigned int step, shift;
+	unsigned long newpp = PP_RXXX;
+
+	if (!mmu_has_feature(MMU_FTR_KERNEL_RO)) {
+		pr_info("R/O rodata not supported\n");
+		return;
+	}
+
+	shift = mmu_psize_defs[mmu_linear_psize].shift;
+	step = 1 << shift;
+
+	start = ((start + step - 1) >> shift) << shift;
+	end = (end >> shift) << shift;
+
+	pr_devel("marking ro start %lx, end %lx, step %x\n",
+			start, end, step);
+
+	for (idx = start; idx < end; idx += step)
+		/* Not sure if we can do much with the return value */
+		mmu_hash_ops.hpte_updateboltedpp(newpp, idx, mmu_linear_psize,
+							mmu_kernel_ssize);
+
+}
+#endif

diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c
index c28165d..8f42309 100644
--- a/arch/powerpc/mm/pgtable-radix.c
+++ b/arch/powerpc/mm/pgtable-radix.c

@@ -108,6 +108,13 @@ int radix__map_kernel_page(unsigned long ea, unsigned long pa,
 	return 0;
 }
 
+#ifdef CONFIG_STRICT_KERNEL_RWX
+void radix__mark_rodata_ro(void)
+{
+	pr_warn("Not yet implemented for radix\n");
+}
+#endif
+
 static inline void __meminit print_mapping(unsigned long start,
 					   unsigned long end,
 					   unsigned long size)

diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index db93cf7..a769e4f 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c

@@ -479,3 +479,12 @@ void mmu_partition_table_set_entry(unsigned int lpid, unsigned long dw0,
 }
 EXPORT_SYMBOL_GPL(mmu_partition_table_set_entry);
 #endif /* CONFIG_PPC_BOOK3S_64 */
+
+#ifdef CONFIG_STRICT_KERNEL_RWX
+void mark_rodata_ro(void)
+{
+	if (radix_enabled())
+		return radix__mark_rodata_ro();
+	return hash__mark_rodata_ro();
+}
+#endif

-- 
2.9.3

We have the basic support in the form of patching R/O
text sections, linker scripts for extending alignment
of text data. We've also got mark_rodata_ro()

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 0153275..ce68c1a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -171,6 +171,7 @@ config PPC
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if COMPAT
 	select HAVE_ARCH_SECCOMP_FILTER
 	select HAVE_ARCH_TRACEHOOK
+	select ARCH_HAS_STRICT_KERNEL_RWX	if PPC64 && PPC_BOOK3S
 	select HAVE_CBPF_JIT			if !PPC64
 	select HAVE_CONTEXT_TRACKING		if PPC64
 	select HAVE_DEBUG_KMEMLEAK

-- 
2.9.3

The check in hpte_find() should be < and not <= for PAGE_OFFSET

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
---
 arch/powerpc/mm/dump_hashpagetable.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/dump_hashpagetable.c b/arch/powerpc/mm/dump_hashpagetable.c
index c6b900f..b1c144b 100644
--- a/arch/powerpc/mm/dump_hashpagetable.c
+++ b/arch/powerpc/mm/dump_hashpagetable.c

@@ -335,7 +335,7 @@ static unsigned long hpte_find(struct pg_state *st, unsigned long ea, int psize)
 	unsigned long rpn, lp_bits;
 	int base_psize = 0, actual_psize = 0;
 
-	if (ea <= PAGE_OFFSET)
+	if (ea < PAGE_OFFSET)
 		return -1;
 
 	/* Look in primary table */

-- 
2.9.3

Hi Balbir,

[auto build test ERROR on powerpc/next]
[also build test ERROR on v4.12-rc3 next-20170602]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Balbir-Singh/Enable-STRICT_KERNEL_RWX/20170603-161759
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-kilauea_defconfig (attached as .config)
compiler: powerpc-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
        wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=powerpc 

All errors (new ones prefixed by >>):

   arch/powerpc/lib/code-patching.c: In function 'kernel_map_addr':

quoted

arch/powerpc/lib/code-patching.c:93:8: error: implicit declaration of function 'map_kernel_page' [-Werror=implicit-function-declaration]

     err = map_kernel_page(
           ^~~~~~~~~~~~~~~
   cc1: all warnings being treated as errors

vim +/map_kernel_page +93 arch/powerpc/lib/code-patching.c

    87	
    88		if (is_vmalloc_addr(addr))
    89			pfn = vmalloc_to_pfn(addr);
    90		else
    91			pfn = __pa_symbol(addr) >> PAGE_SHIFT;
    92	
  > 93		err = map_kernel_page(
    94				(unsigned long)__this_cpu_read(text_poke_area)->addr,
    95				(pfn << PAGE_SHIFT), _PAGE_KERNEL_RW | _PAGE_PRESENT);
    96		pr_devel("Mapped addr %p with pfn %lx\n",

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

On Sat,  3 Jun 2017 17:18:39 +1000
Balbir Singh [off-list ref] wrote:

For CONFIG_STRICT_KERNEL_RWX align __init_begin to 16M.
We use 16M since its the larger of 2M on radix and 16M
on hash for our linear mapping. The plan is to have
.text, .rodata and everything upto __init_begin marked
as RX. Note we still have executable read only data.
We could further align read only data to another 16M
boundary, but then the linker starts using stubs and
that breaks our assembler code in head_64.S

Is this still the case with powerpc next?

Thanks,
Nick

On Sun, Jun 4, 2017 at 2:22 PM, Nicholas Piggin [off-list ref] wrote:

On Sat,  3 Jun 2017 17:18:39 +1000
Balbir Singh [off-list ref] wrote:

quoted

For CONFIG_STRICT_KERNEL_RWX align __init_begin to 16M.
We use 16M since its the larger of 2M on radix and 16M
on hash for our linear mapping. The plan is to have
.text, .rodata and everything upto __init_begin marked
as RX. Note we still have executable read only data.
We could further align read only data to another 16M
boundary, but then the linker starts using stubs and
that breaks our assembler code in head_64.S

Is this still the case with powerpc next?

Sorry, no, I was on linux-next for testing, but I think your linker
stub patches went in very recently. I'll rebase on top and test,
but I am not sure if I want two 16M alignments and bloat the size
of vmlinux. But I'll double check what happens

Balbir Singh.

On Mon, 5 Jun 2017 08:42:40 +1000
Balbir Singh [off-list ref] wrote:

On Sun, Jun 4, 2017 at 2:22 PM, Nicholas Piggin [off-list ref] wrote:

quoted

On Sat,  3 Jun 2017 17:18:39 +1000
Balbir Singh [off-list ref] wrote:
 

quoted

For CONFIG_STRICT_KERNEL_RWX align __init_begin to 16M.
We use 16M since its the larger of 2M on radix and 16M
on hash for our linear mapping. The plan is to have
.text, .rodata and everything upto __init_begin marked
as RX. Note we still have executable read only data.
We could further align read only data to another 16M
boundary, but then the linker starts using stubs and
that breaks our assembler code in head_64.S  

Is this still the case with powerpc next?
 

Sorry, no, I was on linux-next for testing, but I think your linker
stub patches went in very recently. I'll rebase on top and test,

That would be good. I'd like to make sure the linker stub workaround
does work for your case.

but I am not sure if I want two 16M alignments and bloat the size
of vmlinux. But I'll double check what happens

Maybe it could be an option.

Thanks,
Nick

Hi Balbir

Le 04/06/2017 à 01:45, kbuild test robot a écrit :

Hi Balbir,

[auto build test ERROR on powerpc/next]
[also build test ERROR on v4.12-rc3 next-20170602]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Balbir-Singh/Enable-STRICT_KERNEL_RWX/20170603-161759
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-kilauea_defconfig (attached as .config)
compiler: powerpc-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
         wget https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
         chmod +x ~/bin/make.cross
         # save the attached .config to linux build tree
         make.cross ARCH=powerpc

All errors (new ones prefixed by >>):

    arch/powerpc/lib/code-patching.c: In function 'kernel_map_addr':

quoted

quoted

arch/powerpc/lib/code-patching.c:93:8: error: implicit declaration of function 'map_kernel_page' [-Werror=implicit-function-declaration]

      err = map_kernel_page(
            ^~~~~~~~~~~~~~~
    cc1: all warnings being treated as errors

You should probably include my patch (the one renaming map_page() to 
map_kernel_page() ) in as first patch in your serie in order to get a 
clean serie and avoid such reports from the robot.

Christophe

vim +/map_kernel_page +93 arch/powerpc/lib/code-patching.c

     87	
     88		if (is_vmalloc_addr(addr))
     89			pfn = vmalloc_to_pfn(addr);
     90		else
     91			pfn = __pa_symbol(addr) >> PAGE_SHIFT;
     92	
   > 93		err = map_kernel_page(
     94				(unsigned long)__this_cpu_read(text_poke_area)->addr,
     95				(pfn << PAGE_SHIFT), _PAGE_KERNEL_RW | _PAGE_PRESENT);
     96		pr_devel("Mapped addr %p with pfn %lx\n",

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

On Wed, Jun 7, 2017 at 8:25 PM, Christophe LEROY
[off-list ref] wrote:

Hi Balbir

Le 04/06/2017 =C3=A0 01:45, kbuild test robot a =C3=A9crit :

quoted

Hi Balbir,

[auto build test ERROR on powerpc/next]
[also build test ERROR on v4.12-rc3 next-20170602]
[if your patch is applied to the wrong git tree, please drop us a note t=

o

quoted

help improve the system]

url:
https://github.com/0day-ci/linux/commits/Balbir-Singh/Enable-STRICT_KERN=

EL_RWX/20170603-161759

quoted

base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.gi=

t

quoted

next
config: powerpc-kilauea_defconfig (attached as .config)
compiler: powerpc-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
         wget
https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cross=

 -O

quoted

~/bin/make.cross
         chmod +x ~/bin/make.cross
         # save the attached .config to linux build tree
         make.cross ARCH=3Dpowerpc

All errors (new ones prefixed by >>):

    arch/powerpc/lib/code-patching.c: In function 'kernel_map_addr':

quoted

quoted

arch/powerpc/lib/code-patching.c:93:8: error: implicit declaration of
function 'map_kernel_page' [-Werror=3Dimplicit-function-declaration]

      err =3D map_kernel_page(
            ^~~~~~~~~~~~~~~
    cc1: all warnings being treated as errors

You should probably include my patch (the one renaming map_page() to
map_kernel_page() ) in as first patch in your serie in order to get a cle=

an

serie and avoid such reports from the robot.

Christophe

Thanks for the suggestion, I did in my cover letter mention the
pre-requisite is your patch. I'll keep that in mind if there is a v4,
otherwise, we'll need to pull in your patch first and then apply this
series.

Balbir Singh.

Balbir Singh [off-list ref] writes:

On Wed, Jun 7, 2017 at 8:25 PM, Christophe LEROY
[off-list ref] wrote:

quoted

Le 04/06/2017 =C3=A0 01:45, kbuild test robot a =C3=A9crit :

quoted

[auto build test ERROR on powerpc/next]
[also build test ERROR on v4.12-rc3 next-20170602]
[if your patch is applied to the wrong git tree, please drop us a note =

to

quoted

quoted

help improve the system]

url:
https://github.com/0day-ci/linux/commits/Balbir-Singh/Enable-STRICT_KER=

NEL_RWX/20170603-161759

quoted

quoted

base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.g=

it

quoted

quoted

next
config: powerpc-kilauea_defconfig (attached as .config)
compiler: powerpc-linux-gnu-gcc (Debian 6.1.1-9) 6.1.1 20160705
reproduce:
         wget
https://raw.githubusercontent.com/01org/lkp-tests/master/sbin/make.cros=

s -O

quoted

quoted

~/bin/make.cross
         chmod +x ~/bin/make.cross
         # save the attached .config to linux build tree
         make.cross ARCH=3Dpowerpc

All errors (new ones prefixed by >>):

    arch/powerpc/lib/code-patching.c: In function 'kernel_map_addr':

quoted

quoted

arch/powerpc/lib/code-patching.c:93:8: error: implicit declaration of
function 'map_kernel_page' [-Werror=3Dimplicit-function-declaration]

      err =3D map_kernel_page(
            ^~~~~~~~~~~~~~~
    cc1: all warnings being treated as errors

You should probably include my patch (the one renaming map_page() to
map_kernel_page() ) in as first patch in your serie in order to get a cl=

ean

quoted

serie and avoid such reports from the robot.

Thanks for the suggestion, I did in my cover letter mention the
pre-requisite is your patch.

The kbuild robot can't read cover letters :)

I'll keep that in mind if there is a v4,
otherwise, we'll need to pull in your patch first and then apply this
series.

It'll probably be in my next tomorrow anyway.

cheers