Re: [PATCH v9 02/11] powerpc: prepare string/mem functions for KASAN

Wed, 06 Mar 2019 13:54:56 -0800 



Le 04/03/2019 à 06:26, Daniel Axtens a écrit :

Hi Christophe,

diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h
new file mode 100644
index 000000000000..c3161b8fc017
--- /dev/null
+++ b/arch/powerpc/include/asm/kasan.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_KASAN_H
+#define __ASM_KASAN_H
+
+#ifdef CONFIG_KASAN
+#define _GLOBAL_KASAN(fn)      .weak fn ; _GLOBAL(__##fn) ; _GLOBAL(fn)
+#define _GLOBAL_TOC_KASAN(fn)  .weak fn ; _GLOBAL_TOC(__##fn) ; _GLOBAL_TOC(fn)
+#define EXPORT_SYMBOL_KASAN(fn)        EXPORT_SYMBOL(__##fn) ; 
EXPORT_SYMBOL(fn)


I'm having some trouble with this. I get warnings like this:


I don't have such problem, neither with ppc32 nor with ppc64e_defconfig.

What config are you using ?

Another (unrelated) question I have:

On the initial arm64 implementation (39d114ddc682 arm64: add KASAN 
support) they made KASAN implementation depend on SPARSEMEM_VMEMMAP 
(allthough they later removed that dependency with commit e17d8025f07e 
arm64/mm/kasan: don't use vmemmap_populate() to initialize shadow)


So I'm wondering why on your side, KASAN depends on !SPARSEMEM_VMEMMAP

Thanks
Christophe



WARNING: EXPORT symbol "__memcpy" [vmlinux] version generation failed, symbol 
will not be versioned.

It seems to be related to the export line, as if I swap the exports to
do fn before __##fn I get:

WARNING: EXPORT symbol "memset" [vmlinux] version generation failed, symbol 
will not be versioned.

I have narrowed this down to combining 2 EXPORT_SYMBOL()s on one line.
This works - no warning:

EXPORT_SYMBOL(memset)
EXPORT_SYMBOL(__memset)

This throws a warning:

EXPORT_SYMBOL(memset) ; EXPORT_SYMBOL(__memset)

I notice in looking at the diff of preprocessed source we end up
invoking an asm macro that doesn't seem to have a full final argument, I
wonder if that's relevant...

-___EXPORT_SYMBOL __memset, __memset, ; ___EXPORT_SYMBOL memset, memset,
+___EXPORT_SYMBOL __memset, __memset,
+___EXPORT_SYMBOL memset, memset,

I also notice that nowhere else in the source do people have multiple
EXPORT_SYMBOLs on the same line, and other arches seem to just
unconditionally export both symbols on multiple lines.

I have no idea how this works for you - maybe it's affected by something 32bit.

How would you feel about this approach instead? I'm not tied to any of
the names or anything.

diff --git a/arch/powerpc/include/asm/ppc_asm.h 
b/arch/powerpc/include/asm/ppc_asm.h
index e0637730a8e7..7b6a91b448dd 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -214,6 +214,9 @@ name: \

  
  #define DOTSYM(a)      a
  
+#define PROVIDE_WEAK_ALIAS(strongname, weakname) \

+       .weak weakname ; .set weakname, strongname ;
+
  #else

  
  #define XGLUE(a,b) a##b

@@ -236,6 +239,10 @@ GLUE(.,name):

  
  #define DOTSYM(a)      GLUE(.,a)
  
+#define PROVIDE_WEAK_ALIAS(strongname, weakname) \

+       .weak weakname ; .set weakname, strongname ; \
+       .weak DOTSYM(weakname) ; .set DOTSYM(weakname), DOTSYM(strongname) ;
+
  #endif

  
  #else /* 32-bit */

@@ -251,6 +258,9 @@ GLUE(.,name):

  
  #define _GLOBAL_TOC(name) _GLOBAL(name)
  
+#define PROVIDE_WEAK_ALIAS(strongname, weakname) \

+       .weak weakname ; .set weakname, strongname ;
+
  #endif

  
  /*

--- a/arch/powerpc/lib/mem_64.S
+++ b/arch/powerpc/lib/mem_64.S
@@ -33,7 +33,8 @@ EXPORT_SYMBOL(__memset32)
  EXPORT_SYMBOL(__memset64)
  #endif

  
-_GLOBAL_KASAN(memset)

+PROVIDE_WEAK_ALIAS(__memset,memset)
+_GLOBAL(__memset)
         neg     r0,r3
         rlwimi  r4,r4,8,16,23
         andi.   r0,r0,7                 /* # bytes to be 8-byte aligned */
@@ -98,9 +99,11 @@ _GLOBAL_KASAN(memset)
  10:    bflr    31
         stb     r4,0(r6)
         blr
-EXPORT_SYMBOL_KASAN(memset)
+EXPORT_SYMBOL(memset)
+EXPORT_SYMBOL(__memset)

  
-_GLOBAL_TOC_KASAN(memmove)

+PROVIDE_WEAK_ALIAS(__memmove,memove)
+_GLOBAL_TOC(__memmove)
         cmplw   0,r3,r4
         bgt     backwards_memcpy
         b       memcpy
@@ -141,4 +144,5 @@ _GLOBAL(backwards_memcpy)
         beq     2b
         mtctr   r7
         b       1b
-EXPORT_SYMBOL_KASAN(memmove)
+EXPORT_SYMBOL(memmove)
+EXPORT_SYMBOL(__memmove)
diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
index 862b515b8868..7c1b09556cad 100644
--- a/arch/powerpc/lib/memcpy_64.S
+++ b/arch/powerpc/lib/memcpy_64.S
@@ -19,7 +19,8 @@
  #endif

  
         .align  7

-_GLOBAL_TOC_KASAN(memcpy)
+PROVIDE_WEAK_ALIAS(__memcpy,memcpy)
+_GLOBAL_TOC(__memcpy)
  BEGIN_FTR_SECTION
  #ifdef __LITTLE_ENDIAN__
         cmpdi   cr7,r5,0
@@ -230,4 +231,5 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_LD_STD)
  4:     ld      r3,-STACKFRAMESIZE+STK_REG(R31)(r1)     /* return dest pointer 
*/
         blr
  #endif
-EXPORT_SYMBOL_KASAN(memcpy)
+EXPORT_SYMBOL(__memcpy)
+EXPORT_SYMBOL(memcpy)


Regards,
Daniel



+#else
+#define _GLOBAL_KASAN(fn)      _GLOBAL(fn)
+#define _GLOBAL_TOC_KASAN(fn)  _GLOBAL_TOC(fn)
+#define EXPORT_SYMBOL_KASAN(fn)        EXPORT_SYMBOL(fn)
+#endif
+
+#endif
diff --git a/arch/powerpc/include/asm/string.h 
b/arch/powerpc/include/asm/string.h
index 1647de15a31e..9bf6dffb4090 100644
--- a/arch/powerpc/include/asm/string.h
+++ b/arch/powerpc/include/asm/string.h
@@ -4,14 +4,17 @@

  
  #ifdef __KERNEL__
  
+#ifndef CONFIG_KASAN

  #define __HAVE_ARCH_STRNCPY
  #define __HAVE_ARCH_STRNCMP
+#define __HAVE_ARCH_MEMCHR
+#define __HAVE_ARCH_MEMCMP
+#define __HAVE_ARCH_MEMSET16
+#endif
+
  #define __HAVE_ARCH_MEMSET
  #define __HAVE_ARCH_MEMCPY
  #define __HAVE_ARCH_MEMMOVE
-#define __HAVE_ARCH_MEMCMP
-#define __HAVE_ARCH_MEMCHR
-#define __HAVE_ARCH_MEMSET16
  #define __HAVE_ARCH_MEMCPY_FLUSHCACHE

  
  extern char * strcpy(char *,const char *);

@@ -27,7 +30,27 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
  extern void * memchr(const void *,int,__kernel_size_t);
  extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);

  
+void *__memset(void *s, int c, __kernel_size_t count);

+void *__memcpy(void *to, const void *from, __kernel_size_t n);
+void *__memmove(void *to, const void *from, __kernel_size_t n);
+
+#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
+/*
+ * For files that are not instrumented (e.g. mm/slub.c) we
+ * should use not instrumented version of mem* functions.
+ */
+#define memcpy(dst, src, len) __memcpy(dst, src, len)
+#define memmove(dst, src, len) __memmove(dst, src, len)
+#define memset(s, c, n) __memset(s, c, n)
+
+#ifndef __NO_FORTIFY
+#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
+#endif
+
+#endif
+
  #ifdef CONFIG_PPC64
+#ifndef CONFIG_KASAN
  #define __HAVE_ARCH_MEMSET32
  #define __HAVE_ARCH_MEMSET64

  
@@ -49,8 +72,11 @@ static inline void *memset64(uint64_t *p, uint64_t v, __kernel_size_t n)

  {
        return __memset64(p, v, n * 8);
  }
+#endif
  #else
+#ifndef CONFIG_KASAN
  #define __HAVE_ARCH_STRLEN
+#endif

  
  extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);

  #endif
diff --git a/arch/powerpc/kernel/prom_init_check.sh 
b/arch/powerpc/kernel/prom_init_check.sh
index 667df97d2595..181fd10008ef 100644
--- a/arch/powerpc/kernel/prom_init_check.sh
+++ b/arch/powerpc/kernel/prom_init_check.sh
@@ -16,8 +16,16 @@
  # If you really need to reference something from prom_init.o add
  # it to the list below:

  
+grep "^CONFIG_KASAN=y$" .config >/dev/null

+if [ $? -eq 0 ]
+then
+       MEM_FUNCS="__memcpy __memset"
+else
+       MEM_FUNCS="memcpy memset"
+fi
+
  WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
-_end enter_prom memcpy memset reloc_offset __secondary_hold
+_end enter_prom $MEM_FUNCS reloc_offset __secondary_hold
  __secondary_hold_acknowledge __secondary_hold_spinloop __start
  strcmp strcpy strlcpy strlen strncmp strstr kstrtobool logo_linux_clut224
  reloc_got2 kernstart_addr memstart_addr linux_banner _stext
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 79396e184bca..47a4de434c22 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -8,9 +8,14 @@ ccflags-$(CONFIG_PPC64)        := $(NO_MINIMAL_TOC)
  CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
  CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)

  
-obj-y += string.o alloc.o code-patching.o feature-fixups.o

+obj-y += alloc.o code-patching.o feature-fixups.o

  
-obj-$(CONFIG_PPC32)	+= div64.o copy_32.o crtsavres.o strlen_32.o

+ifndef CONFIG_KASAN
+obj-y  +=      string.o memcmp_$(BITS).o
+obj-$(CONFIG_PPC32)    += strlen_32.o
+endif
+
+obj-$(CONFIG_PPC32)    += div64.o copy_32.o crtsavres.o

  
  obj-$(CONFIG_FUNCTION_ERROR_INJECTION)	+= error-inject.o
  
@@ -34,7 +39,7 @@ obj64-$(CONFIG_KPROBES_SANITY_TEST)	+= test_emulate_step.o \

                                           test_emulate_step_exec_instr.o

  
  obj-y			+= checksum_$(BITS).o checksum_wrappers.o \

-                          string_$(BITS).o memcmp_$(BITS).o
+                          string_$(BITS).o

  
  obj-y			+= sstep.o ldstfp.o quad.o

  obj64-y                       += quad.o
diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index ba66846fe973..fc4fa7246200 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -14,6 +14,7 @@
  #include <asm/ppc_asm.h>
  #include <asm/export.h>
  #include <asm/code-patching-asm.h>
+#include <asm/kasan.h>

  
  #define COPY_16_BYTES		\

        lwz     r7,4(r4);       \
@@ -68,6 +69,7 @@ CACHELINE_BYTES = L1_CACHE_BYTES
  LG_CACHELINE_BYTES = L1_CACHE_SHIFT
  CACHELINE_MASK = (L1_CACHE_BYTES-1)

  
+#ifndef CONFIG_KASAN

  _GLOBAL(memset16)
        rlwinm. r0 ,r5, 31, 1, 31
        addi    r6, r3, -4
@@ -81,6 +83,7 @@ _GLOBAL(memset16)
        sth     r4, 4(r6)
        blr
  EXPORT_SYMBOL(memset16)
+#endif

  
  /*

   * Use dcbz on the complete cache lines in the destination
@@ -91,7 +94,7 @@ EXPORT_SYMBOL(memset16)
   * We therefore skip the optimised bloc that uses dcbz. This jump is
   * replaced by a nop once cache is active. This is done in machine_init()
   */
-_GLOBAL(memset)
+_GLOBAL_KASAN(memset)
        cmplwi  0,r5,4
        blt     7f

  
@@ -150,7 +153,7 @@ _GLOBAL(memset)

  9:    stbu    r4,1(r6)
        bdnz    9b
        blr
-EXPORT_SYMBOL(memset)
+EXPORT_SYMBOL_KASAN(memset)

  
  /*

   * This version uses dcbz on the complete cache lines in the
@@ -163,12 +166,12 @@ EXPORT_SYMBOL(memset)
   * We therefore jump to generic_memcpy which doesn't use dcbz. This jump is
   * replaced by a nop once cache is active. This is done in machine_init()
   */
-_GLOBAL(memmove)
+_GLOBAL_KASAN(memmove)
        cmplw   0,r3,r4
        bgt     backwards_memcpy
        /* fall through */

  
-_GLOBAL(memcpy)

+_GLOBAL_KASAN(memcpy)
  1:    b       generic_memcpy
        patch_site      1b, patch__memcpy_nocache

  
@@ -242,8 +245,8 @@ _GLOBAL(memcpy)

        stbu    r0,1(r6)
        bdnz    40b
  65:   blr
-EXPORT_SYMBOL(memcpy)
-EXPORT_SYMBOL(memmove)
+EXPORT_SYMBOL_KASAN(memcpy)
+EXPORT_SYMBOL_KASAN(memmove)

  
  generic_memcpy:

        srwi.   r7,r5,3
diff --git a/arch/powerpc/lib/mem_64.S b/arch/powerpc/lib/mem_64.S
index 3c3be02f33b7..7cd6cf6822a2 100644
--- a/arch/powerpc/lib/mem_64.S
+++ b/arch/powerpc/lib/mem_64.S
@@ -12,7 +12,9 @@
  #include <asm/errno.h>
  #include <asm/ppc_asm.h>
  #include <asm/export.h>
+#include <asm/kasan.h>

  
+#ifndef CONFIG_KASAN

  _GLOBAL(__memset16)
        rlwimi  r4,r4,16,0,15
        /* fall through */
@@ -29,8 +31,9 @@ _GLOBAL(__memset64)
  EXPORT_SYMBOL(__memset16)
  EXPORT_SYMBOL(__memset32)
  EXPORT_SYMBOL(__memset64)
+#endif

  
-_GLOBAL(memset)

+_GLOBAL_KASAN(memset)
        neg     r0,r3
        rlwimi  r4,r4,8,16,23
        andi.   r0,r0,7                 /* # bytes to be 8-byte aligned */
@@ -95,9 +98,9 @@ _GLOBAL(memset)
  10:   bflr    31
        stb     r4,0(r6)
        blr
-EXPORT_SYMBOL(memset)
+EXPORT_SYMBOL_KASAN(memset)

  
-_GLOBAL_TOC(memmove)

+_GLOBAL_TOC_KASAN(memmove)
        cmplw   0,r3,r4
        bgt     backwards_memcpy
        b       memcpy
@@ -138,4 +141,4 @@ _GLOBAL(backwards_memcpy)
        beq     2b
        mtctr   r7
        b       1b
-EXPORT_SYMBOL(memmove)
+EXPORT_SYMBOL_KASAN(memmove)
diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
index 273ea67e60a1..862b515b8868 100644
--- a/arch/powerpc/lib/memcpy_64.S
+++ b/arch/powerpc/lib/memcpy_64.S
@@ -11,6 +11,7 @@
  #include <asm/export.h>
  #include <asm/asm-compat.h>
  #include <asm/feature-fixups.h>
+#include <asm/kasan.h>

  
  #ifndef SELFTEST_CASE

  /* For big-endian, 0 == most CPUs, 1 == POWER6, 2 == Cell */
@@ -18,7 +19,7 @@
  #endif

  
  	.align	7

-_GLOBAL_TOC(memcpy)
+_GLOBAL_TOC_KASAN(memcpy)
  BEGIN_FTR_SECTION
  #ifdef __LITTLE_ENDIAN__
        cmpdi   cr7,r5,0
@@ -229,4 +230,4 @@ END_FTR_SECTION_IFCLR(CPU_FTR_UNALIGNED_LD_STD)
  4:    ld      r3,-STACKFRAMESIZE+STK_REG(R31)(r1)     /* return dest pointer 
*/
        blr
  #endif
-EXPORT_SYMBOL(memcpy)
+EXPORT_SYMBOL_KASAN(memcpy)
--
2.13.3






















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