ARM: 7174/1: Fix build error in kprobes test code on Thumb2 kernels

When compiling kprobes-test-thumb.c an error like below may occur:

/tmp/ccKcuJcG.s:19179: Error: offset out of range

This is caused by the compiler underestimating the size of the inline
assembler instructions containing ".space 0x1000" and failing to spill
the literal pool in time to prevent the generation of PC relative load
instruction with invalid offsets.

The fix implemented by this patch is to replace a single large .space
directive by a number of 4 byte .space's. This requires splitting the
macros which generate test cases for branch instructions into two forms:
one with, and one without support for inserting extra code between
branch and target.

Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Jon Medhurst <jon.medhurst@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

diff --git a/arch/arm/kernel/kprobes-test-thumb.c b/arch/arm/kernel/kprobes-test-thumb.c
index 5e726c31c45aef5084a7e7ddf07bb1762ed4c403..5d8b857922220b4be4e9babf6e050c94625a56eb 100644 (file)
--- a/arch/arm/kernel/kprobes-test-thumb.c
+++ b/arch/arm/kernel/kprobes-test-thumb.c
@@ -222,8 +222,8 @@ void kprobe_thumb16_test_cases(void)
 DONT_TEST_IN_ITBLOCK(
        TEST_BF_R(  "cbnz       r",0,0, ", 2f")
        TEST_BF_R(  "cbz        r",2,-1,", 2f")
-       TEST_BF_RX( "cbnz       r",4,1, ", 2f",0x20)
-       TEST_BF_RX( "cbz        r",7,0, ", 2f",0x40)
+       TEST_BF_RX( "cbnz       r",4,1, ", 2f", SPACE_0x20)
+       TEST_BF_RX( "cbz        r",7,0, ", 2f", SPACE_0x40)
 )
        TEST_R("sxth    r0, r",7, HH1,"")
        TEST_R("sxth    r7, r",0, HH2,"")
@@ -246,7 +246,7 @@ DONT_TEST_IN_ITBLOCK(
        TESTCASE_START(code)            \
        TEST_ARG_PTR(13, offset)        \
        TEST_ARG_END("")                \
-       TEST_BRANCH_F(code,0)           \
+       TEST_BRANCH_F(code)             \
        TESTCASE_END
 
        TEST("push      {r0}")
@@ -319,8 +319,8 @@ CONDITION_INSTRUCTIONS(8,
 
        TEST_BF(  "b    2f")
        TEST_BB(  "b    2b")
-       TEST_BF_X("b    2f", 0x400)
-       TEST_BB_X("b    2b", 0x400)
+       TEST_BF_X("b    2f", SPACE_0x400)
+       TEST_BB_X("b    2b", SPACE_0x400)
 
        TEST_GROUP("Testing instructions in IT blocks")
 
@@ -746,7 +746,7 @@ CONDITION_INSTRUCTIONS(22,
        TEST_BB("bne.w  2b")
        TEST_BF("bgt.w  2f")
        TEST_BB("blt.w  2b")
-       TEST_BF_X("bpl.w        2f",0x1000)
+       TEST_BF_X("bpl.w        2f", SPACE_0x1000)
 )
 
        TEST_UNSUPPORTED("msr   cpsr, r0")
@@ -786,11 +786,11 @@ CONDITION_INSTRUCTIONS(22,
 
        TEST_BF(  "b.w  2f")
        TEST_BB(  "b.w  2b")
-       TEST_BF_X("b.w  2f", 0x1000)
+       TEST_BF_X("b.w  2f", SPACE_0x1000)
 
        TEST_BF(  "bl.w 2f")
        TEST_BB(  "bl.w 2b")
-       TEST_BB_X("bl.w 2b", 0x1000)
+       TEST_BB_X("bl.w 2b", SPACE_0x1000)
 
        TEST_X( "blx    __dummy_arm_subroutine",
                ".arm                           \n\t"

diff --git a/arch/arm/kernel/kprobes-test.h b/arch/arm/kernel/kprobes-test.h
index 0dc5d77b9356bcd86b4b0c087bf642bc6396e06e..e28a869b1ae4b7be5abfb7d088c3214bfe2caab7 100644 (file)
--- a/arch/arm/kernel/kprobes-test.h
+++ b/arch/arm/kernel/kprobes-test.h
@@ -149,23 +149,31 @@ struct test_arg_end {
        "1:     "instruction"                           \n\t"   \
        "       nop                                     \n\t"
 
-#define TEST_BRANCH_F(instruction, xtra_dist)                  \
+#define TEST_BRANCH_F(instruction)                             \
        TEST_INSTRUCTION(instruction)                           \
-       ".if "#xtra_dist"                               \n\t"   \
        "       b       99f                             \n\t"   \
-       ".space "#xtra_dist"                            \n\t"   \
-       ".endif                                         \n\t"   \
+       "2:     nop                                     \n\t"
+
+#define TEST_BRANCH_B(instruction)                             \
+       "       b       50f                             \n\t"   \
+       "       b       99f                             \n\t"   \
+       "2:     nop                                     \n\t"   \
+       "       b       99f                             \n\t"   \
+       TEST_INSTRUCTION(instruction)
+
+#define TEST_BRANCH_FX(instruction, codex)                     \
+       TEST_INSTRUCTION(instruction)                           \
+       "       b       99f                             \n\t"   \
+       codex"                                          \n\t"   \
        "       b       99f                             \n\t"   \
        "2:     nop                                     \n\t"
 
-#define TEST_BRANCH_B(instruction, xtra_dist)                  \
+#define TEST_BRANCH_BX(instruction, codex)                     \
        "       b       50f                             \n\t"   \
        "       b       99f                             \n\t"   \
        "2:     nop                                     \n\t"   \
        "       b       99f                             \n\t"   \
-       ".if "#xtra_dist"                               \n\t"   \
-       ".space "#xtra_dist"                            \n\t"   \
-       ".endif                                         \n\t"   \
+       codex"                                          \n\t"   \
        TEST_INSTRUCTION(instruction)
 
 #define TESTCASE_END                                           \
@@ -301,47 +309,60 @@ struct test_arg_end {
        TESTCASE_START(code1 #reg1 code2)       \
        TEST_ARG_PTR(reg1, val1)                \
        TEST_ARG_END("")                        \
-       TEST_BRANCH_F(code1 #reg1 code2, 0)     \
+       TEST_BRANCH_F(code1 #reg1 code2)        \
        TESTCASE_END
 
-#define TEST_BF_X(code, xtra_dist)             \
+#define TEST_BF(code)                          \
        TESTCASE_START(code)                    \
        TEST_ARG_END("")                        \
-       TEST_BRANCH_F(code, xtra_dist)          \
+       TEST_BRANCH_F(code)                     \
        TESTCASE_END
 
-#define TEST_BB_X(code, xtra_dist)             \
+#define TEST_BB(code)                          \
        TESTCASE_START(code)                    \
        TEST_ARG_END("")                        \
-       TEST_BRANCH_B(code, xtra_dist)          \
+       TEST_BRANCH_B(code)                     \
        TESTCASE_END
 
-#define TEST_BF_RX(code1, reg, val, code2, xtra_dist)  \
-       TESTCASE_START(code1 #reg code2)                \
-       TEST_ARG_REG(reg, val)                          \
-       TEST_ARG_END("")                                \
-       TEST_BRANCH_F(code1 #reg code2, xtra_dist)      \
+#define TEST_BF_R(code1, reg, val, code2)      \
+       TESTCASE_START(code1 #reg code2)        \
+       TEST_ARG_REG(reg, val)                  \
+       TEST_ARG_END("")                        \
+       TEST_BRANCH_F(code1 #reg code2)         \
        TESTCASE_END
 
-#define TEST_BB_RX(code1, reg, val, code2, xtra_dist)  \
-       TESTCASE_START(code1 #reg code2)                \
-       TEST_ARG_REG(reg, val)                          \
-       TEST_ARG_END("")                                \
-       TEST_BRANCH_B(code1 #reg code2, xtra_dist)      \
+#define TEST_BB_R(code1, reg, val, code2)      \
+       TESTCASE_START(code1 #reg code2)        \
+       TEST_ARG_REG(reg, val)                  \
+       TEST_ARG_END("")                        \
+       TEST_BRANCH_B(code1 #reg code2)         \
        TESTCASE_END
 
-#define TEST_BF(code)  TEST_BF_X(code, 0)
-#define TEST_BB(code)  TEST_BB_X(code, 0)
-
-#define TEST_BF_R(code1, reg, val, code2) TEST_BF_RX(code1, reg, val, code2, 0)
-#define TEST_BB_R(code1, reg, val, code2) TEST_BB_RX(code1, reg, val, code2, 0)
-
 #define TEST_BF_RR(code1, reg1, val1, code2, reg2, val2, code3)        \
        TESTCASE_START(code1 #reg1 code2 #reg2 code3)           \
        TEST_ARG_REG(reg1, val1)                                \
        TEST_ARG_REG(reg2, val2)                                \
        TEST_ARG_END("")                                        \
-       TEST_BRANCH_F(code1 #reg1 code2 #reg2 code3, 0)         \
+       TEST_BRANCH_F(code1 #reg1 code2 #reg2 code3)            \
+       TESTCASE_END
+
+#define TEST_BF_X(code, codex)                 \
+       TESTCASE_START(code)                    \
+       TEST_ARG_END("")                        \
+       TEST_BRANCH_FX(code, codex)             \
+       TESTCASE_END
+
+#define TEST_BB_X(code, codex)                 \
+       TESTCASE_START(code)                    \
+       TEST_ARG_END("")                        \
+       TEST_BRANCH_BX(code, codex)             \
+       TESTCASE_END
+
+#define TEST_BF_RX(code1, reg, val, code2, codex)      \
+       TESTCASE_START(code1 #reg code2)                \
+       TEST_ARG_REG(reg, val)                          \
+       TEST_ARG_END("")                                \
+       TEST_BRANCH_FX(code1 #reg code2, codex)         \
        TESTCASE_END
 
 #define TEST_X(code, codex)                    \
@@ -372,6 +393,25 @@ struct test_arg_end {
        TESTCASE_END
 
 
+/*
+ * Macros for defining space directives spread over multiple lines.
+ * These are required so the compiler guesses better the length of inline asm
+ * code and will spill the literal pool early enough to avoid generating PC
+ * relative loads with out of range offsets.
+ */
+#define TWICE(x)       x x
+#define SPACE_0x8      TWICE(".space 4\n\t")
+#define SPACE_0x10     TWICE(SPACE_0x8)
+#define SPACE_0x20     TWICE(SPACE_0x10)
+#define SPACE_0x40     TWICE(SPACE_0x20)
+#define SPACE_0x80     TWICE(SPACE_0x40)
+#define SPACE_0x100    TWICE(SPACE_0x80)
+#define SPACE_0x200    TWICE(SPACE_0x100)
+#define SPACE_0x400    TWICE(SPACE_0x200)
+#define SPACE_0x800    TWICE(SPACE_0x400)
+#define SPACE_0x1000   TWICE(SPACE_0x800)
+
+
 /* Various values used in test cases... */
 #define N(val) (val ^ 0xffffffff)
 #define VAL1   0x12345678