Aurelio Bernal
eaf88aca2a
* test(ghidra): require pending multi-HI16 coverage in the real MIPS relocatable lane Post-merge review on #1950: the relocation oracle exposes coverage.multiple_hi16, but the real-Ghidra lane never required it, and Clang's C output never produces a LO16 that resolves several pending HI16s. Ghidra's loader could therefore mishandle that stream while the lane still passed, although most GCC-built kernel modules checked contain it. The relocatable fixture adds an assembly block with two lui %hi(rea_mips_rel_carry); LLVM's relocation sort then leaves one HI16 pending until a later LO16 that resolves it together with another HI16, including the carry. The lane now requires multiple_hi16: false on the previous fixture, true for all three variants (LE, BE, soft-float module) on real Ghidra 12.1.4. * test(ghidra): make the MIPS multi-HI16 fixture independent of relocation sorting Review on #1974: the block used two %lo of rea_mips_rel_carry, a symbol with other %lo uses, so the relocation stream depended on the assembler's HI16/LO16 sort. Clang 21 happened to leave a HI16 pending; Clang 17 (per review) and GNU as 2.45 (checked here: HI@4 LO@8 HI@0 LO@10) pair each HI16 with its own LO16, so multiple_hi16 stays false and the lane fails. Use a dedicated symbol with two %hi and exactly one %lo. Any assembler that orders each HI16 before a matching LO16 must then emit both HI16s ahead of that single LO16: Clang 21 gives HI@0 HI@4 LO@8, GNU as 2.45 gives HI@4 HI@0 LO@8. The real-Ghidra lane passes for LE, BE and the soft-float module variant with multiple_hi16 true.
77 lines
2.8 KiB
C
77 lines
2.8 KiB
C
/* Relocatable (ET_REL) static-analysis fixture, built with -c -G0 and never
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* executed or linked by REA. It exercises the relocations Linux MIPS kernel
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* modules use: R_MIPS_26 calls, HI16/LO16 address pairs (one HI16 shared by
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* several LO16s, two HI16s resolved by one LO16, and a LO16 >= 0x8000 that
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* forces a HI16 carry), R_MIPS_32
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* data words, and undefined external code and data symbols. powf is an
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* external whose float prototype Ghidra's C library archive supplies by name,
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* so soft-float builds must give it the soft-float prototype too.
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*/
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extern int rea_mips_rel_external(int value);
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extern int rea_mips_rel_external_data;
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extern float powf(float base, float exponent);
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struct rea_mips_rel_pair {
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int first;
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int second;
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};
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struct rea_mips_rel_pair rea_mips_rel_pair = { 0x1111, 0x2222 };
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/* Places rea_mips_rel_carry past a signed 16-bit low-half boundary. */
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char rea_mips_rel_padding[0x8000] = { 1 };
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int rea_mips_rel_carry = 0x3333;
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/* Referenced only by rea_mips_rel_highs, so its single LO16 stays unique. */
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int rea_mips_rel_highs_target = 0x4444;
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static const char rea_mips_rel_marker[] = "rea-mips-relocatable-fixture";
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__attribute__((noinline)) int rea_mips_rel_leaf(int value)
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{
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return value * 3 + rea_mips_rel_pair.first + rea_mips_rel_pair.second;
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}
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__attribute__((noinline, long_call)) int rea_mips_rel_far(int value);
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int rea_mips_rel_far(int value)
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{
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return value + rea_mips_rel_marker[value & 7] + rea_mips_rel_carry;
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}
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int (*const rea_mips_rel_table[])(int) = {
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rea_mips_rel_leaf,
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rea_mips_rel_far,
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rea_mips_rel_external,
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};
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__attribute__((noinline)) int rea_mips_rel_scaled(int value)
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{
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float scaled = powf(1.5f, 2.5f);
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return value ^ *(int *)&scaled;
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}
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/* Most GCC-built kernel modules checked contain LO16s that resolve several
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* pending HI16s; Clang does not produce that from C. Two %hi and exactly one
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* %lo of a symbol nothing else references: any assembler that orders each
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* HI16 before a matching LO16 (GNU as, every LLVM version) must emit both
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* HI16s ahead of that single LO16, which therefore resolves both.
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*/
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__asm__(".text\n"
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".globl rea_mips_rel_highs\n"
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".type rea_mips_rel_highs, @function\n"
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".set push\n"
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".set noreorder\n"
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"rea_mips_rel_highs:\n"
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" lui $2, %hi(rea_mips_rel_highs_target)\n"
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" lui $3, %hi(rea_mips_rel_highs_target)\n"
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" addiu $2, $2, %lo(rea_mips_rel_highs_target)\n"
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" jr $31\n"
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" move $3, $2\n"
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".set pop\n"
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".size rea_mips_rel_highs, .-rea_mips_rel_highs\n");
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int rea_mips_rel_entry(int value)
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{
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return rea_mips_rel_leaf(value) + rea_mips_rel_far(value) +
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rea_mips_rel_external(value) + rea_mips_rel_external_data +
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rea_mips_rel_table[value & 1](value) + rea_mips_rel_scaled(value);
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}
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