Merge tag 'mips_4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux

Pull MIPS updates from Paul Burton:
 "Here's the main MIPS pull for Linux 4.21. Core architecture changes
  include:

   - Syscall tables & definitions for unistd.h are now generated by
     scripts, providing greater consistency with other architectures &
     making it easier to add new syscalls.

   - Support for building kernels with no floating point support, upon
     which any userland attempting to use floating point instructions
     will receive a SIGILL. Mostly useful to shrink the kernel & as
     preparation for nanoMIPS support which does not yet include FP.

   - MIPS SIMD Architecture (MSA) vector register context is now exposed
     by ptrace via a new NT_MIPS_MSA regset.

   - ASIDs are now stored as 64b values even for MIPS32 kernels,
     expanding the ASID version field sufficiently that we don't need to
     worry about overflow & avoiding rare issues with reused ASIDs that
     have been observed in the wild.

   - The branch delay slot "emulation" page is now mapped without write
     permission for the user, preventing its use as a nice location for
     attacks to execute malicious code from.

   - Support for ioremap_prot(), primarily to allow gdb or other ptrace
     users the ability to view their tracee's memory using the same
     cache coherency attribute.

   - Optimizations to more cpu_has_* macros, allowing more to be
     compile-time constant where possible.

   - Enable building the whole kernel with UBSAN instrumentation.

   - Enable building the kernel with link-time dead code & data
     elimination.

  Platform specific changes include:

   - The Boston board gains a workaround for DMA prefetching issues with
     the EG20T Platform Controller Hub that it uses.

   - Cleanups to Cavium Octeon code removing about 20k lines of
     redundant code, mostly unused or duplicate register definitions in
     headers.

   - defconfig updates for the DECstation machines, including new
     defconfigs for r4k & 64b machines.

   - Further work on Loongson 3 support.

   - DMA fixes for SiByte machines"

* tag 'mips_4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: (95 commits)
  MIPS: math-emu: Write-protect delay slot emulation pages
  MIPS: Remove struct mm_context_t fp_mode_switching field
  mips: generate uapi header and system call table files
  mips: add system call table generation support
  mips: remove syscall table entries
  mips: add +1 to __NR_syscalls in uapi header
  mips: rename scall64-64.S to scall64-n64.S
  mips: remove unused macros
  mips: add __NR_syscalls along with __NR_Linux_syscalls
  MIPS: Expand MIPS32 ASIDs to 64 bits
  MIPS: OCTEON: delete redundant register definitions
  MIPS: OCTEON: cvmx_gmxx_inf_mode: use oldest forward compatible definition
  MIPS: OCTEON: cvmx_mio_fus_dat3: use oldest forward compatible definition
  MIPS: OCTEON: cvmx_pko_mem_debug8: use oldest forward compatible definition
  MIPS: OCTEON: octeon-usb: use common gpio_bit definition
  MIPS: OCTEON: enable all OCTEON drivers in defconfig
  mips: annotate implicit fall throughs
  MIPS: Hardcode cpu_has_mips* where target ISA allows
  MIPS: MT: Remove norps command line parameter
  MIPS: Only include mmzone.h when CONFIG_NEED_MULTIPLE_NODES=y
  ...

arch/mips/kernel/traps.c

@@ -50,6 +50,7 @@
 #include <asm/fpu.h>
 #include <asm/fpu_emulator.h>
 #include <asm/idle.h>
+#include <asm/isa-rev.h>
 #include <asm/mips-cps.h>
 #include <asm/mips-r2-to-r6-emul.h>
 #include <asm/mipsregs.h>
@@ -277,8 +278,10 @@ static void __show_regs(const struct pt_regs *regs)
 #ifdef CONFIG_CPU_HAS_SMARTMIPS
 	printk("Acx    : %0*lx\n", field, regs->acx);
 #endif
-	printk("Hi    : %0*lx\n", field, regs->hi);
-	printk("Lo    : %0*lx\n", field, regs->lo);
+	if (MIPS_ISA_REV < 6) {
+		printk("Hi    : %0*lx\n", field, regs->hi);
+		printk("Lo    : %0*lx\n", field, regs->lo);
+	}
 
 	/*
 	 * Saved cp0 registers
@@ -706,6 +709,8 @@ asmlinkage void do_ov(struct pt_regs *regs)
 	exception_exit(prev_state);
 }
 
+#ifdef CONFIG_MIPS_FP_SUPPORT
+
 /*
  * Send SIGFPE according to FCSR Cause bits, which must have already
  * been masked against Enable bits.  This is impotant as Inexact can
@@ -794,9 +799,6 @@ static int simulate_fp(struct pt_regs *regs, unsigned int opcode,
 	regs->cp0_epc = old_epc;
 	regs->regs[31] = old_ra;
 
-	/* Save the FP context to struct thread_struct */
-	lose_fpu(1);
-
 	/* Run the emulator */
 	sig = fpu_emulator_cop1Handler(regs, &current->thread.fpu, 1,
 				       &fault_addr);
@@ -848,8 +850,6 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
 		 * register operands before invoking the emulator, which seems
 		 * a bit extreme for what should be an infrequent event.
 		 */
-		/* Ensure 'resume' not overwrite saved fp context again. */
-		lose_fpu(1);
 
 		/* Run the emulator */
 		sig = fpu_emulator_cop1Handler(regs, &current->thread.fpu, 1,
@@ -876,6 +876,45 @@ out:
 	exception_exit(prev_state);
 }
 
+/*
+ * MIPS MT processors may have fewer FPU contexts than CPU threads. If we've
+ * emulated more than some threshold number of instructions, force migration to
+ * a "CPU" that has FP support.
+ */
+static void mt_ase_fp_affinity(void)
+{
+#ifdef CONFIG_MIPS_MT_FPAFF
+	if (mt_fpemul_threshold > 0 &&
+	     ((current->thread.emulated_fp++ > mt_fpemul_threshold))) {
+		/*
+		 * If there's no FPU present, or if the application has already
+		 * restricted the allowed set to exclude any CPUs with FPUs,
+		 * we'll skip the procedure.
+		 */
+		if (cpumask_intersects(&current->cpus_allowed, &mt_fpu_cpumask)) {
+			cpumask_t tmask;
+
+			current->thread.user_cpus_allowed
+				= current->cpus_allowed;
+			cpumask_and(&tmask, &current->cpus_allowed,
+				    &mt_fpu_cpumask);
+			set_cpus_allowed_ptr(current, &tmask);
+			set_thread_flag(TIF_FPUBOUND);
+		}
+	}
+#endif /* CONFIG_MIPS_MT_FPAFF */
+}
+
+#else /* !CONFIG_MIPS_FP_SUPPORT */
+
+static int simulate_fp(struct pt_regs *regs, unsigned int opcode,
+		       unsigned long old_epc, unsigned long old_ra)
+{
+	return -1;
+}
+
+#endif /* !CONFIG_MIPS_FP_SUPPORT */
+
 void do_trap_or_bp(struct pt_regs *regs, unsigned int code, int si_code,
 	const char *str)
 {
@@ -1159,35 +1198,6 @@ out:
 	exception_exit(prev_state);
 }
 
-/*
- * MIPS MT processors may have fewer FPU contexts than CPU threads. If we've
- * emulated more than some threshold number of instructions, force migration to
- * a "CPU" that has FP support.
- */
-static void mt_ase_fp_affinity(void)
-{
-#ifdef CONFIG_MIPS_MT_FPAFF
-	if (mt_fpemul_threshold > 0 &&
-	     ((current->thread.emulated_fp++ > mt_fpemul_threshold))) {
-		/*
-		 * If there's no FPU present, or if the application has already
-		 * restricted the allowed set to exclude any CPUs with FPUs,
-		 * we'll skip the procedure.
-		 */
-		if (cpumask_intersects(&current->cpus_allowed, &mt_fpu_cpumask)) {
-			cpumask_t tmask;
-
-			current->thread.user_cpus_allowed
-				= current->cpus_allowed;
-			cpumask_and(&tmask, &current->cpus_allowed,
-				    &mt_fpu_cpumask);
-			set_cpus_allowed_ptr(current, &tmask);
-			set_thread_flag(TIF_FPUBOUND);
-		}
-	}
-#endif /* CONFIG_MIPS_MT_FPAFF */
-}
-
 /*
  * No lock; only written during early bootup by CPU 0.
  */
@@ -1215,23 +1225,25 @@ static int default_cu2_call(struct notifier_block *nfb, unsigned long action,
 	return NOTIFY_OK;
 }
 
+#ifdef CONFIG_MIPS_FP_SUPPORT
+
 static int enable_restore_fp_context(int msa)
 {
 	int err, was_fpu_owner, prior_msa;
+	bool first_fp;
 
-	if (!used_math()) {
-		/* First time FP context user. */
+	/* Initialize context if it hasn't been used already */
+	first_fp = init_fp_ctx(current);
+
+	if (first_fp) {
 		preempt_disable();
-		err = init_fpu();
+		err = own_fpu_inatomic(1);
 		if (msa && !err) {
 			enable_msa();
-			init_msa_upper();
 			set_thread_flag(TIF_USEDMSA);
 			set_thread_flag(TIF_MSA_CTX_LIVE);
 		}
 		preempt_enable();
-		if (!err)
-			set_used_math();
 		return err;
 	}
 
@@ -1322,17 +1334,23 @@ out:
 	return 0;
 }
 
+#else /* !CONFIG_MIPS_FP_SUPPORT */
+
+static int enable_restore_fp_context(int msa)
+{
+	return SIGILL;
+}
+
+#endif /* CONFIG_MIPS_FP_SUPPORT */
+
 asmlinkage void do_cpu(struct pt_regs *regs)
 {
 	enum ctx_state prev_state;
 	unsigned int __user *epc;
 	unsigned long old_epc, old31;
-	void __user *fault_addr;
 	unsigned int opcode;
-	unsigned long fcr31;
 	unsigned int cpid;
-	int status, err;
-	int sig;
+	int status;
 
 	prev_state = exception_enter();
 	cpid = (regs->cp0_cause >> CAUSEB_CE) & 3;
@@ -1370,6 +1388,7 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 
 		break;
 
+#ifdef CONFIG_MIPS_FP_SUPPORT
 	case 3:
 		/*
 		 * The COP3 opcode space and consequently the CP0.Status.CU3
@@ -1389,7 +1408,11 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 		}
 		/* Fall through.  */
 
-	case 1:
+	case 1: {
+		void __user *fault_addr;
+		unsigned long fcr31;
+		int err, sig;
+
 		err = enable_restore_fp_context(0);
 
 		if (raw_cpu_has_fpu && !err)
@@ -1410,6 +1433,13 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 			mt_ase_fp_affinity();
 
 		break;
+	}
+#else /* CONFIG_MIPS_FP_SUPPORT */
+	case 1:
+	case 3:
+		force_sig(SIGILL, current);
+		break;
+#endif /* CONFIG_MIPS_FP_SUPPORT */
 
 	case 2:
 		raw_notifier_call_chain(&cu2_chain, CU2_EXCEPTION, regs);