RISC-V updates for v7.2-rc4

- Call flush_cache_vmap() after populating new vmemmap pages, on all
   architectures.  This avoids spurious faults on RISC-V
   microarchitectures that cache PTEs marked as non-present
 
 - Disable LTO for the vDSO to prevent the compiler from eliding
   functions that are used, but which don't appear to be
 
 - Fix an issue with libgcc's unwinder and signal handlers by dropping
   an unnecessary CFI landing pad instruction in __vdso_rt_sigreturn
   (similar to what was done on ARM64)
 
 - Avoid reading uninitialized memory under certain conditions in
   hwprobe_get_cpus()
 
 - Save some memory and I$ when CONFIG_DYNAMIC_FTRACE=n by avoiding
   our four-byte function alignment requirement in that case
 
 - Avoid clang warnings about null-pointer arithmetic in the I/O-port
   accessor macros (inb, outb, etc.) by ifdeffing them out when
   !CONFIG_HAS_IOPORT
 
 - Make the build of the lazy TLB flushing code in the vmalloc path
   depend on CONFIG_64BIT and CONFIG_MMU (since those platforms are the
   only ones that use it)
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Merge tag 'riscv-for-linus-7.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V fixes from Paul Walmsley:

 - Call flush_cache_vmap() after populating new vmemmap pages, on all
   architectures. This avoids spurious faults on RISC-V
   microarchitectures that cache PTEs marked as non-present

 - Disable LTO for the vDSO to prevent the compiler from eliding
   functions that are used, but which don't appear to be

 - Fix an issue with libgcc's unwinder and signal handlers by dropping
   an unnecessary CFI landing pad instruction in __vdso_rt_sigreturn
   (similar to what was done on ARM64)

 - Avoid reading uninitialized memory under certain conditions in
   hwprobe_get_cpus()

 - Save some memory and I$ when CONFIG_DYNAMIC_FTRACE=n by avoiding our
   four-byte function alignment requirement in that case

 - Avoid clang warnings about null-pointer arithmetic in the I/O-port
   accessor macros (inb, outb, etc.) by ifdeffing them out when
   !CONFIG_HAS_IOPORT

 - Make the build of the lazy TLB flushing code in the vmalloc path
   depend on CONFIG_64BIT and CONFIG_MMU (since those platforms are the
   only ones that use it)

* tag 'riscv-for-linus-7.2-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  riscv: hwprobe: Avoid uninitialized read in hwprobe_get_cpus()
  arch/riscv: vdso: remove CFI landing pad from rt_sigreturn
  riscv: vdso: Do not use LTO for the vDSO
  riscv: io: avoid null-pointer arithmetic in PIO helpers
  riscv: Gate FUNCTION_ALIGNMENT_4B on DYNAMIC_FTRACE
  mm/sparse-vmemmap: flush_cache_vmap() after hotplugging vmemmap
  riscv: mm: Make mark_new_valid_map() stuff depend on 64BIT && MMU

arch/riscv/Kconfig

@@ -157,7 +157,7 @@ config RISCV
 	select HAVE_DEBUG_KMEMLEAK
 	select HAVE_DMA_CONTIGUOUS if MMU
 	select HAVE_DYNAMIC_FTRACE if MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE)
-	select FUNCTION_ALIGNMENT_4B if HAVE_DYNAMIC_FTRACE && RISCV_ISA_C
+	select FUNCTION_ALIGNMENT_4B if DYNAMIC_FTRACE && RISCV_ISA_C
 	select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS if HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS
 	select HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS if (DYNAMIC_FTRACE_WITH_ARGS && !CFI)
 	select HAVE_DYNAMIC_FTRACE_WITH_ARGS if HAVE_DYNAMIC_FTRACE

arch/riscv/include/asm/cacheflush.h

@@ -40,7 +40,7 @@ do {							\
 		flush_icache_mm(vma->vm_mm, 0);		\
 } while (0)
 
-#ifdef CONFIG_64BIT
+#if defined(CONFIG_64BIT) && defined(CONFIG_MMU)
 /* This is accessed in assembly code. cpumask_var_t would be too complex. */
 extern DECLARE_BITMAP(new_valid_map_cpus, NR_CPUS);
 extern char _end[];
@@ -56,7 +56,8 @@ static inline void mark_new_valid_map(void)
 #define flush_cache_vmap flush_cache_vmap
 static inline void flush_cache_vmap(unsigned long start, unsigned long end)
 {
-	if (is_vmalloc_or_module_addr((void *)start))
+	if (is_vmalloc_or_module_addr((void *)start) ||
+	    (start >= VMEMMAP_START && end <= VMEMMAP_END))
 		mark_new_valid_map();
 }
 #define flush_cache_vmap_early(start, end)	local_flush_tlb_kernel_range(start, end)

arch/riscv/include/asm/io.h

@@ -102,12 +102,14 @@ __io_reads_ins(reads, u32, l, __io_br(), __io_ar(addr))
 #define readsw(addr, buffer, count) __readsw(addr, buffer, count)
 #define readsl(addr, buffer, count) __readsl(addr, buffer, count)
 
+#ifdef CONFIG_HAS_IOPORT
 __io_reads_ins(ins,  u8, b, __io_pbr(), __io_par(addr))
 __io_reads_ins(ins, u16, w, __io_pbr(), __io_par(addr))
 __io_reads_ins(ins, u32, l, __io_pbr(), __io_par(addr))
 #define insb(addr, buffer, count) __insb(PCI_IOBASE + (addr), buffer, count)
 #define insw(addr, buffer, count) __insw(PCI_IOBASE + (addr), buffer, count)
 #define insl(addr, buffer, count) __insl(PCI_IOBASE + (addr), buffer, count)
+#endif
 
 __io_writes_outs(writes,  u8, b, __io_bw(), __io_aw())
 __io_writes_outs(writes, u16, w, __io_bw(), __io_aw())
@@ -116,26 +118,32 @@ __io_writes_outs(writes, u32, l, __io_bw(), __io_aw())
 #define writesw(addr, buffer, count) __writesw(addr, buffer, count)
 #define writesl(addr, buffer, count) __writesl(addr, buffer, count)
 
+#ifdef CONFIG_HAS_IOPORT
 __io_writes_outs(outs,  u8, b, __io_pbw(), __io_paw())
 __io_writes_outs(outs, u16, w, __io_pbw(), __io_paw())
 __io_writes_outs(outs, u32, l, __io_pbw(), __io_paw())
 #define outsb(addr, buffer, count) __outsb(PCI_IOBASE + (addr), buffer, count)
 #define outsw(addr, buffer, count) __outsw(PCI_IOBASE + (addr), buffer, count)
 #define outsl(addr, buffer, count) __outsl(PCI_IOBASE + (addr), buffer, count)
+#endif
 
 #ifdef CONFIG_64BIT
 __io_reads_ins(reads, u64, q, __io_br(), __io_ar(addr))
 #define readsq(addr, buffer, count) __readsq(addr, buffer, count)
 
+#ifdef CONFIG_HAS_IOPORT
 __io_reads_ins(ins, u64, q, __io_pbr(), __io_par(addr))
 #define insq(addr, buffer, count) __insq(PCI_IOBASE + (addr), buffer, count)
+#endif
 
 __io_writes_outs(writes, u64, q, __io_bw(), __io_aw())
 #define writesq(addr, buffer, count) __writesq(addr, buffer, count)
 
+#ifdef CONFIG_HAS_IOPORT
 __io_writes_outs(outs, u64, q, __io_pbr(), __io_paw())
 #define outsq(addr, buffer, count) __outsq(PCI_IOBASE + (addr), buffer, count)
 #endif
+#endif
 
 #include <asm-generic/io.h>
 

arch/riscv/kernel/entry.S

@@ -137,7 +137,7 @@ SYM_CODE_START(handle_exception)
 .Lrestore_kernel_tpsp:
 	csrr tp, CSR_SCRATCH
 
-#ifdef CONFIG_64BIT
+#if defined(CONFIG_64BIT) && defined(CONFIG_MMU)
 	/*
 	 * The RISC-V kernel does not flush TLBs on all CPUS after each new
 	 * vmalloc mapping or kfence_unprotect(), which may result in

arch/riscv/kernel/sys_hwprobe.c

@@ -450,6 +450,7 @@ static int hwprobe_get_cpus(struct riscv_hwprobe __user *pairs,
 	if (cpusetsize > cpumask_size())
 		cpusetsize = cpumask_size();
 
+	cpumask_clear(&cpus);
 	ret = copy_from_user(&cpus, cpus_user, cpusetsize);
 	if (ret)
 		return -EFAULT;

arch/riscv/kernel/vdso/Makefile

@@ -69,9 +69,9 @@ CPPFLAGS_$(vdso_lds) += -DHAS_VGETTIMEOFDAY
 endif
 
 # Disable -pg to prevent insert call site
-CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)
-CFLAGS_REMOVE_getrandom.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)
-CFLAGS_REMOVE_hwprobe.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS)
+CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_LTO)
+CFLAGS_REMOVE_getrandom.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_LTO)
+CFLAGS_REMOVE_hwprobe.o = $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_LTO)
 
 # Force dependency
 $(obj)/$(vdso_o): $(obj)/$(vdso_so)

arch/riscv/kernel/vdso/rt_sigreturn.S

@@ -7,11 +7,19 @@
 #include <asm/unistd.h>
 #include <asm/assembler.h>
 
+/*
+ * WARNING: Do NOT add a CFI landing pad at the start of this function.
+ * Unwinders such as libgcc identify the sigreturn trampoline by matching the
+ * instruction sequence. Adding a landing pad here would break unwinding from
+ * signal handlers.
+ *
+ * This trampoline is used only for signal return and not via an indirect
+ * call/jump from userspace, so adding CFI landing pad is unnecessary.
+ */
 	.text
 SYM_FUNC_START(__vdso_rt_sigreturn)
 	.cfi_startproc
 	.cfi_signal_frame
-	vdso_lpad
 	li a7, __NR_rt_sigreturn
 	ecall
 	.cfi_endproc

arch/riscv/mm/init.c

@@ -37,7 +37,9 @@
 
 #include "../kernel/head.h"
 
+#if defined(CONFIG_64BIT) && defined(CONFIG_MMU)
 DECLARE_BITMAP(new_valid_map_cpus, NR_CPUS);
+#endif
 
 struct kernel_mapping kernel_map __ro_after_init;
 EXPORT_SYMBOL(kernel_map);

mm/sparse-vmemmap.c

@@ -564,6 +564,8 @@ struct page * __meminit __populate_section_memmap(unsigned long pfn,
 	if (r < 0)
 		return NULL;
 
+	flush_cache_vmap(start, end);
+
 	return pfn_to_page(pfn);
 }