powerpc fixes for 4.10 #3

The main change is we're reverting the initial stack protector support we
 merged this cycle. It turns out to not work on toolchains built with libc
 support, and fixing it will be need to wait for another release.
 
 And the rest are all fairly minor:
  - Some pasemi machines were not booting due to a missing error check in
    prom_find_boot_cpu().
  - In EEH we were checking a pointer rather than the bool it pointed to.
  - The clang build was broken by a BUILD_BUG_ON() we added.
  - The radix (Power9 only) version of map_kernel_page() was broken if our
    memory size was a multiple of 2MB, which it generally isn't.
 
 Thanks to:
   Darren Stevens, Gavin Shan, Reza Arbab.
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Merge tag 'powerpc-4.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:
 "The main change is we're reverting the initial stack protector support
  we merged this cycle. It turns out to not work on toolchains built
  with libc support, and fixing it will be need to wait for another
  release.

  And the rest are all fairly minor:

   - Some pasemi machines were not booting due to a missing error check
     in prom_find_boot_cpu()

   - In EEH we were checking a pointer rather than the bool it pointed
     to

   - The clang build was broken by a BUILD_BUG_ON() we added.

   - The radix (Power9 only) version of map_kernel_page() was broken if
     our memory size was a multiple of 2MB, which it generally isn't

  Thanks to: Darren Stevens, Gavin Shan, Reza Arbab"

* tag 'powerpc-4.10-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/mm: Use the correct pointer when setting a 2MB pte
  powerpc: Fix build failure with clang due to BUILD_BUG_ON()
  powerpc: Revert the initial stack protector support
  powerpc/eeh: Fix wrong flag passed to eeh_unfreeze_pe()
  powerpc: Add missing error check to prom_find_boot_cpu()

arch/powerpc/Kconfig

@@ -164,7 +164,6 @@ config PPC
 	select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE
 	select HAVE_ARCH_HARDENED_USERCOPY
 	select HAVE_KERNEL_GZIP
-	select HAVE_CC_STACKPROTECTOR
 
 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN

arch/powerpc/include/asm/cpu_has_feature.h

@@ -23,7 +23,9 @@ static __always_inline bool cpu_has_feature(unsigned long feature)
 {
 	int i;
 
+#ifndef __clang__ /* clang can't cope with this */
 	BUILD_BUG_ON(!__builtin_constant_p(feature));
+#endif
 
 #ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
 	if (!static_key_initialized) {

arch/powerpc/include/asm/mmu.h

@@ -160,7 +160,9 @@ static __always_inline bool mmu_has_feature(unsigned long feature)
 {
 	int i;
 
+#ifndef __clang__ /* clang can't cope with this */
 	BUILD_BUG_ON(!__builtin_constant_p(feature));
+#endif
 
 #ifdef CONFIG_JUMP_LABEL_FEATURE_CHECK_DEBUG
 	if (!static_key_initialized) {

arch/powerpc/include/asm/stackprotector.h

@@ -1,40 +0,0 @@
-/*
- * GCC stack protector support.
- *
- * Stack protector works by putting predefined pattern at the start of
- * the stack frame and verifying that it hasn't been overwritten when
- * returning from the function.  The pattern is called stack canary
- * and gcc expects it to be defined by a global variable called
- * "__stack_chk_guard" on PPC.  This unfortunately means that on SMP
- * we cannot have a different canary value per task.
- */
-
-#ifndef _ASM_STACKPROTECTOR_H
-#define _ASM_STACKPROTECTOR_H
-
-#include <linux/random.h>
-#include <linux/version.h>
-#include <asm/reg.h>
-
-extern unsigned long __stack_chk_guard;
-
-/*
- * Initialize the stackprotector canary value.
- *
- * NOTE: this must only be called from functions that never return,
- * and it must always be inlined.
- */
-static __always_inline void boot_init_stack_canary(void)
-{
-	unsigned long canary;
-
-	/* Try to get a semi random initial value. */
-	get_random_bytes(&canary, sizeof(canary));
-	canary ^= mftb();
-	canary ^= LINUX_VERSION_CODE;
-
-	current->stack_canary = canary;
-	__stack_chk_guard = current->stack_canary;
-}
-
-#endif	/* _ASM_STACKPROTECTOR_H */

arch/powerpc/kernel/Makefile

@@ -19,10 +19,6 @@ CFLAGS_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
 CFLAGS_btext.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
 CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
 
-# -fstack-protector triggers protection checks in this code,
-# but it is being used too early to link to meaningful stack_chk logic.
-CFLAGS_prom_init.o += $(call cc-option, -fno-stack-protector)
-
 ifdef CONFIG_FUNCTION_TRACER
 # Do not trace early boot code
 CFLAGS_REMOVE_cputable.o = -mno-sched-epilog $(CC_FLAGS_FTRACE)

arch/powerpc/kernel/asm-offsets.c

@@ -91,9 +91,6 @@ int main(void)
 	DEFINE(TI_livepatch_sp, offsetof(struct thread_info, livepatch_sp));
 #endif
 
-#ifdef CONFIG_CC_STACKPROTECTOR
-	DEFINE(TSK_STACK_CANARY, offsetof(struct task_struct, stack_canary));
-#endif
 	DEFINE(KSP, offsetof(struct thread_struct, ksp));
 	DEFINE(PT_REGS, offsetof(struct thread_struct, regs));
 #ifdef CONFIG_BOOKE

arch/powerpc/kernel/eeh_driver.c

@@ -545,7 +545,7 @@ static void *eeh_pe_detach_dev(void *data, void *userdata)
 static void *__eeh_clear_pe_frozen_state(void *data, void *flag)
 {
 	struct eeh_pe *pe = (struct eeh_pe *)data;
-	bool *clear_sw_state = flag;
+	bool clear_sw_state = *(bool *)flag;
 	int i, rc = 1;
 
 	for (i = 0; rc && i < 3; i++)

arch/powerpc/kernel/entry_32.S

@@ -674,11 +674,7 @@ BEGIN_FTR_SECTION
 	mtspr	SPRN_SPEFSCR,r0		/* restore SPEFSCR reg */
 END_FTR_SECTION_IFSET(CPU_FTR_SPE)
 #endif /* CONFIG_SPE */
-#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP)
-	lwz	r0,TSK_STACK_CANARY(r2)
-	lis	r4,__stack_chk_guard@ha
-	stw	r0,__stack_chk_guard@l(r4)
-#endif
+
 	lwz	r0,_CCR(r1)
 	mtcrf	0xFF,r0
 	/* r3-r12 are destroyed -- Cort */

arch/powerpc/kernel/process.c

@@ -64,12 +64,6 @@
 #include <linux/kprobes.h>
 #include <linux/kdebug.h>
 
-#ifdef CONFIG_CC_STACKPROTECTOR
-#include <linux/stackprotector.h>
-unsigned long __stack_chk_guard __read_mostly;
-EXPORT_SYMBOL(__stack_chk_guard);
-#endif
-
 /* Transactional Memory debug */
 #ifdef TM_DEBUG_SW
 #define TM_DEBUG(x...) printk(KERN_INFO x)

arch/powerpc/kernel/prom_init.c

@@ -2834,6 +2834,9 @@ static void __init prom_find_boot_cpu(void)
 
 	cpu_pkg = call_prom("instance-to-package", 1, 1, prom_cpu);
 
+	if (!PHANDLE_VALID(cpu_pkg))
+		return;
+
 	prom_getprop(cpu_pkg, "reg", &rval, sizeof(rval));
 	prom.cpu = be32_to_cpu(rval);
 

arch/powerpc/mm/pgtable-radix.c

@@ -65,7 +65,7 @@ int radix__map_kernel_page(unsigned long ea, unsigned long pa,
 		if (!pmdp)
 			return -ENOMEM;
 		if (map_page_size == PMD_SIZE) {
-			ptep = (pte_t *)pudp;
+			ptep = pmdp_ptep(pmdp);
 			goto set_the_pte;
 		}
 		ptep = pte_alloc_kernel(pmdp, ea);
@@ -90,7 +90,7 @@ int radix__map_kernel_page(unsigned long ea, unsigned long pa,
 		}
 		pmdp = pmd_offset(pudp, ea);
 		if (map_page_size == PMD_SIZE) {
-			ptep = (pte_t *)pudp;
+			ptep = pmdp_ptep(pmdp);
 			goto set_the_pte;
 		}
 		if (!pmd_present(*pmdp)) {