RISC-V Fixes for 5.12-rc6

I have a handful of fixes for 5.12:
 
 * A fix for a stack tracing regression related to "const register asm"
   variables, which have unexpected behavior.
 * A fix to put_user() that ensures the value to be written is evaluated
   before enabling access to userspace memory..
 * A fix to align the exception vector table correctly, so we don't rely
   on the firmware's handling of unaligned accesses.
 * A build fix to make NUMA depend on MMU, which triggers some
   randconfigs.
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Merge tag 'riscv-for-linus-5.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V fixes from Palmer Dabbelt:
 "A handful of fixes for 5.12:

   - fix a stack tracing regression related to "const register asm"
     variables, which have unexpected behavior.

   - ensure the value to be written by put_user() is evaluated before
     enabling access to userspace memory..

   - align the exception vector table correctly, so we don't rely on the
     firmware's handling of unaligned accesses.

   - build fix to make NUMA depend on MMU, which triggered on some
     randconfigs"

* tag 'riscv-for-linus-5.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: Make NUMA depend on MMU
  riscv: remove unneeded semicolon
  riscv,entry: fix misaligned base for excp_vect_table
  riscv: evaluate put_user() arg before enabling user access
  riscv: Drop const annotation for sp

arch/riscv/Kconfig

@@ -314,7 +314,7 @@ endchoice
 # Common NUMA Features
 config NUMA
 	bool "NUMA Memory Allocation and Scheduler Support"
-	depends on SMP
+	depends on SMP && MMU
 	select GENERIC_ARCH_NUMA
 	select OF_NUMA
 	select ARCH_SUPPORTS_NUMA_BALANCING

arch/riscv/include/asm/uaccess.h

@@ -306,7 +306,9 @@ do {								\
  * data types like structures or arrays.
  *
  * @ptr must have pointer-to-simple-variable type, and @x must be assignable
- * to the result of dereferencing @ptr.
+ * to the result of dereferencing @ptr. The value of @x is copied to avoid
+ * re-ordering where @x is evaluated inside the block that enables user-space
+ * access (thus bypassing user space protection if @x is a function).
  *
  * Caller must check the pointer with access_ok() before calling this
  * function.
@@ -316,12 +318,13 @@ do {								\
 #define __put_user(x, ptr)					\
 ({								\
 	__typeof__(*(ptr)) __user *__gu_ptr = (ptr);		\
+	__typeof__(*__gu_ptr) __val = (x);			\
 	long __pu_err = 0;					\
 								\
 	__chk_user_ptr(__gu_ptr);				\
 								\
 	__enable_user_access();					\
-	__put_user_nocheck(x, __gu_ptr, __pu_err);		\
+	__put_user_nocheck(__val, __gu_ptr, __pu_err);		\
 	__disable_user_access();				\
 								\
 	__pu_err;						\

arch/riscv/kernel/entry.S

@@ -447,6 +447,7 @@ ENDPROC(__switch_to)
 #endif
 
 	.section ".rodata"
+	.align LGREG
 	/* Exception vector table */
 ENTRY(excp_vect_table)
 	RISCV_PTR do_trap_insn_misaligned

arch/riscv/kernel/stacktrace.c

@@ -14,7 +14,7 @@
 
 #include <asm/stacktrace.h>
 
-register const unsigned long sp_in_global __asm__("sp");
+register unsigned long sp_in_global __asm__("sp");
 
 #ifdef CONFIG_FRAME_POINTER
 

arch/riscv/mm/kasan_init.c

@@ -216,7 +216,7 @@ void __init kasan_init(void)
 			break;
 
 		kasan_populate(kasan_mem_to_shadow(start), kasan_mem_to_shadow(end));
-	};
+	}
 
 	for (i = 0; i < PTRS_PER_PTE; i++)
 		set_pte(&kasan_early_shadow_pte[i],