NonSFI mode: Make tests/common/register_set.h PIC-friendly.

tests/common/register_set.h

Index: tests/common/register_set.h
diff --git a/tests/common/register_set.h b/tests/common/register_set.h
index 5bb747d174b1c8fa1d02e322504c2c2d95fbf7ee..a6133804e7202abe9b6df0158bcee0753be54217 100644
--- a/tests/common/register_set.h
+++ b/tests/common/register_set.h
@@ -240,7 +240,7 @@ extern const uint8_t kX86FlagBits[5];
         #def_func ":\n" \
         /* Push most of "struct NaClSignalContext" in reverse order. */ \
         "push $0\n"  /* Leave space for flags */ \
-        "push $" #def_func "\n"  /* Fill out prog_ctr with known value */ \
+        "push $0 \n" /* Leave space for prog_ctr */ \
         "push %edi\n" \
         "push %esi\n" \
         "push %ebp\n" \
@@ -252,6 +252,12 @@ extern const uint8_t kX86FlagBits[5];
         /* Save flags. */ \
         SAVE_X86_FLAGS_INTO_REG("%eax") \
         "movl %eax, 0x24(%esp)\n" \
+        /* Obtain def_func from GOT to fill progg_ctr with known value. */ \
+        "call 0f\n" \
+        "0: popl %eax\n" \
+        "1: addl $_GLOBAL_OFFSET_TABLE_ + (1b - 0b), %eax\n" \
+        "movl " #def_func "@GOT(%eax), %eax\n" \
+        "movl %eax, 0x20(%esp)\n" \
         /* Adjust saved %esp value to account for preceding pushes. */ \
         "addl $5 * 4, 0x10(%esp)\n" \
         /* Save argument to callee_func() temporarily. */ \
@@ -335,8 +341,20 @@ extern const uint8_t kX86FlagBits[5];
         /* Save the rest of struct NaClSignalContext */ \
         "push {r0-r8}\n" \
         /* Now save a correct prog_ctr value */ \
-        "adr r0, " #def_func "\n" \
-        "str r0, [sp, #0x3c]\n" \
+        "ldr r2, 11f\n" \
+        "1:\n" \
+        "add r2, pc, r2\n"  /* obtain GLOBAL_OFFSET_TABLE */    \
+        "ldr r3, 12f\n" \
+        "add r2, r2, r3\n" \
+        "bic r2, r2, #0xc0000000\n" /* SFI constraint */ \
+        "ldr r3, [r2]\n" /* obtain def_func */ \
+        "str r3, [sp, #0x3c]\n" \
+        "b 2f\n" /* leave some space for PC-relative data. */ \
+        "11:\n" \
+        ".word _GLOBAL_OFFSET_TABLE_-(1b + 8)\n" \

[Junichi Uekawa, 2014/09/15 03:43:08]

hmmm,  pnacl-clang claims it doesn't know ".word " directive 

/ssd/nacl2/native_client/toolchain/linux_x86/pnacl_newlib/bin/pnacl-clang
-std=gnu99 -arch arm --pnacl-allow-native --pnacl-allow-translate -std=gnu99
-Wstrict-prototypes -O2 -g -fomit-frame-pointer -fasynchronous-unwind-tables
-Wall -Wundef -fdiagnostics-show-option -pedantic -Werror -Wno-variadic-macros
-Wno-extra-semi -Wno-unused-private-field --pnacl-arm-bias -DNACL_BUILD_ARCH=arm
-DNACL_BUILD_SUBARCH=32 -D__STDC_LIMIT_MACROS=1 -D__STDC_FORMAT_MACROS=1
-D_GNU_SOURCE=1 -D_DEFAULT_SOURCE=1 -D_BSD_SOURCE=1 -D_POSIX_C_SOURCE=199506
-D_XOPEN_SOURCE=600 -DDYNAMIC_ANNOTATIONS_ENABLED=1
-DDYNAMIC_ANNOTATIONS_PREFIX=NACL_ -DNACL_WINDOWS=0 -DNACL_OSX=0 -DNACL_LINUX=0
-DNACL_ANDROID=0 -Iscons-out/nacl-arm-pnacl-clang/include -I/ssd/nacl2 -c -o
scons-out/nacl-arm-pnacl-clang/obj/tests/exception_test/exception_test.o
tests/exception_test/exception_test.c                                           
                                                            

[Junichi Uekawa, 2014/09/15 12:36:51]

changing to .long made this pass, but clang-3.4 doesn't like function(GOT)
expression.
clang-3.5 seems to allow it.



On 2014/09/15 03:43:08, Junichi Uekawa wrote:

+        "12:\n" \
+        ".word " #def_func "(GOT)\n" \
+        "2:\n" \
         /* Save CPSR (flags) register, a.k.a. APSR for user mode */ \
         "mrs r0, apsr\n" \
         "str r0, [sp, #0x40]\n" \