Merge tag 'powerpc-5.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:
 "A pretty small batch for us, and apologies for it being a bit late, I
  wanted to sneak Christophe's user_access_begin() series in.

  Summary:

   - Implement user_access_begin() and friends for our platforms that
     support controlling kernel access to userspace.

   - Enable CONFIG_VMAP_STACK on 32-bit Book3S and 8xx.

   - Some tweaks to our pseries IOMMU code to allow SVMs ("secure"
     virtual machines) to use the IOMMU.

   - Add support for CLOCK_{REALTIME/MONOTONIC}_COARSE to the 32-bit
     VDSO, and some other improvements.

   - A series to use the PCI hotplug framework to control opencapi
     card's so that they can be reset and re-read after flashing a new
     FPGA image.

  As well as other minor fixes and improvements as usual.

  Thanks to: Alastair D'Silva, Alexandre Ghiti, Alexey Kardashevskiy,
  Andrew Donnellan, Aneesh Kumar K.V, Anju T Sudhakar, Bai Yingjie, Chen
  Zhou, Christophe Leroy, Frederic Barrat, Greg Kurz, Jason A.
  Donenfeld, Joel Stanley, Jordan Niethe, Julia Lawall, Krzysztof
  Kozlowski, Laurent Dufour, Laurentiu Tudor, Linus Walleij, Michael
  Bringmann, Nathan Chancellor, Nicholas Piggin, Nick Desaulniers,
  Oliver O'Halloran, Peter Ujfalusi, Pingfan Liu, Ram Pai, Randy Dunlap,
  Russell Currey, Sam Bobroff, Sebastian Andrzej Siewior, Shawn
  Anastasio, Stephen Rothwell, Steve Best, Sukadev Bhattiprolu, Thiago
  Jung Bauermann, Tyrel Datwyler, Vaibhav Jain"

* tag 'powerpc-5.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (131 commits)
  powerpc: configs: Cleanup old Kconfig options
  powerpc/configs/skiroot: Enable some more hardening options
  powerpc/configs/skiroot: Disable xmon default & enable reboot on panic
  powerpc/configs/skiroot: Enable security features
  powerpc/configs/skiroot: Update for symbol movement only
  powerpc/configs/skiroot: Drop default n CONFIG_CRYPTO_ECHAINIV
  powerpc/configs/skiroot: Drop HID_LOGITECH
  powerpc/configs: Drop NET_VENDOR_HP which moved to staging
  powerpc/configs: NET_CADENCE became NET_VENDOR_CADENCE
  powerpc/configs: Drop CONFIG_QLGE which moved to staging
  powerpc: Do not consider weak unresolved symbol relocations as bad
  powerpc/32s: Fix kasan_early_hash_table() for CONFIG_VMAP_STACK
  powerpc: indent to improve Kconfig readability
  powerpc: Provide initial documentation for PAPR hcalls
  powerpc: Implement user_access_save() and user_access_restore()
  powerpc: Implement user_access_begin and friends
  powerpc/32s: Prepare prevent_user_access() for user_access_end()
  powerpc/32s: Drop NULL addr verification
  powerpc/kuap: Fix set direction in allow/prevent_user_access()
  powerpc/32s: Fix bad_kuap_fault()
  ...

2 files changed, 64 insertions, 9 deletions

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index f9dc597b0b86..3c0ba22dc360 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -102,41 +102,91 @@ static inline void kuap_update_sr(u32 sr, u32 addr, u32 end)
 	isync();	/* Context sync required after mtsrin() */
 }
 
-static inline void allow_user_access(void __user *to, const void __user *from, u32 size)
+static __always_inline void allow_user_access(void __user *to, const void __user *from,
+					      u32 size, unsigned long dir)
 {
 	u32 addr, end;
 
-	if (__builtin_constant_p(to) && to == NULL)
+	BUILD_BUG_ON(!__builtin_constant_p(dir));
+	BUILD_BUG_ON(dir == KUAP_CURRENT);
+
+	if (!(dir & KUAP_WRITE))
 		return;
 
 	addr = (__force u32)to;
 
-	if (!addr || addr >= TASK_SIZE || !size)
+	if (unlikely(addr >= TASK_SIZE || !size))
 		return;
 
 	end = min(addr + size, TASK_SIZE);
+
 	current->thread.kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) & 0xf);
 	kuap_update_sr(mfsrin(addr) & ~SR_KS, addr, end);	/* Clear Ks */
 }
 
-static inline void prevent_user_access(void __user *to, const void __user *from, u32 size)
+static __always_inline void prevent_user_access(void __user *to, const void __user *from,
+						u32 size, unsigned long dir)
 {
-	u32 addr = (__force u32)to;
-	u32 end = min(addr + size, TASK_SIZE);
+	u32 addr, end;
+
+	BUILD_BUG_ON(!__builtin_constant_p(dir));
+
+	if (dir == KUAP_CURRENT) {
+		u32 kuap = current->thread.kuap;
 
-	if (!addr || addr >= TASK_SIZE || !size)
+		if (unlikely(!kuap))
+			return;
+
+		addr = kuap & 0xf0000000;
+		end = kuap << 28;
+	} else if (dir & KUAP_WRITE) {
+		addr = (__force u32)to;
+		end = min(addr + size, TASK_SIZE);
+
+		if (unlikely(addr >= TASK_SIZE || !size))
+			return;
+	} else {
 		return;
+	}
 
 	current->thread.kuap = 0;
 	kuap_update_sr(mfsrin(addr) | SR_KS, addr, end);	/* set Ks */
 }
 
-static inline bool bad_kuap_fault(struct pt_regs *regs, bool is_write)
+static inline unsigned long prevent_user_access_return(void)
+{
+	unsigned long flags = current->thread.kuap;
+	unsigned long addr = flags & 0xf0000000;
+	unsigned long end = flags << 28;
+	void __user *to = (__force void __user *)addr;
+
+	if (flags)
+		prevent_user_access(to, to, end - addr, KUAP_READ_WRITE);
+
+	return flags;
+}
+
+static inline void restore_user_access(unsigned long flags)
 {
+	unsigned long addr = flags & 0xf0000000;
+	unsigned long end = flags << 28;
+	void __user *to = (__force void __user *)addr;
+
+	if (flags)
+		allow_user_access(to, to, end - addr, KUAP_READ_WRITE);
+}
+
+static inline bool
+bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
+{
+	unsigned long begin = regs->kuap & 0xf0000000;
+	unsigned long end = regs->kuap << 28;
+
 	if (!is_write)
 		return false;
 
-	return WARN(!regs->kuap, "Bug: write fault blocked by segment registers !");
+	return WARN(address < begin || address >= end,
+		    "Bug: write fault blocked by segment registers !");
 }
 
 #endif /* CONFIG_PPC_KUAP */
diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 0796533d37dd..5b39c11e884a 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -193,7 +193,12 @@ int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
 #else
 #define VMALLOC_START ((((long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)))
 #endif
+
+#ifdef CONFIG_KASAN_VMALLOC
+#define VMALLOC_END	_ALIGN_DOWN(ioremap_bot, PAGE_SIZE << KASAN_SHADOW_SCALE_SHIFT)
+#else
 #define VMALLOC_END	ioremap_bot
+#endif
 
 #ifndef __ASSEMBLY__
 #include <linux/sched.h>