Arm: Fix out of range conditional branch (PR/24991)
The fix for PR12848 introduced an off by one error in the mask, this corrected the negative overflows but not the positive overflows. As a result the conditional branch instructions accepted a too wide positive immediate which resulted in it corrupting the instruction during encoding. The relocation I believe has been incorrectly named, to be consistent with the other relocations it should have been named BRANCH21 which is why the masks for it are confusing. I've replaced the masks with a function out_of_range_p which should make it harder to make such mistakes. The mask for BL/BLX on Armv6t+ is also wrong, the extended range is 25-bits and so the mask should be checking for 24-bits for positive overflow. gas/ChangeLog: PR gas/24991 * config/tc-arm.c (out_of_range_p): New. (md_apply_fix): Use it in BFD_RELOC_THUMB_PCREL_BRANCH9, BFD_RELOC_THUMB_PCREL_BRANCH12, BFD_RELOC_THUMB_PCREL_BRANCH20, BFD_RELOC_THUMB_PCREL_BRANCH23, BFD_RELOC_THUMB_PCREL_BRANCH25 * testsuite/gas/arm/pr24991.d: New test. * testsuite/gas/arm/pr24991.l: New test. * testsuite/gas/arm/pr24991.s: New test.
This commit is contained in:
Tamar Christina
parent
352f6bc3e5
commit
e8f8842d90
5 changed files with 38 additions and 7 deletions
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@ -1,3 +1,14 @@
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2019-09-24 Tamar Christina <tamar.christina@arm.com>
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PR gas/24991
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* config/tc-arm.c (out_of_range_p): New.
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(md_apply_fix): Use it in BFD_RELOC_THUMB_PCREL_BRANCH9,
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BFD_RELOC_THUMB_PCREL_BRANCH12, BFD_RELOC_THUMB_PCREL_BRANCH20,
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BFD_RELOC_THUMB_PCREL_BRANCH23, BFD_RELOC_THUMB_PCREL_BRANCH25
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* testsuite/gas/arm/pr24991.d: New test.
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* testsuite/gas/arm/pr24991.l: New test.
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* testsuite/gas/arm/pr24991.s: New test.
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2019-09-23 Alan Modra <amodra@gmail.com>
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* config/obj-ecoff.c: Include ecoff-bfd.h.
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@ -107,6 +107,15 @@ enum arm_float_abi
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should define CPU_DEFAULT here. */
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#endif
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/* Perform range checks on positive and negative overflows by checking if the
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VALUE given fits within the range of an BITS sized immediate. */
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static bfd_boolean out_of_range_p (offsetT value, offsetT bits)
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{
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gas_assert (bits < (offsetT)(sizeof (value) * 8));
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return (value & ~((1 << bits)-1))
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&& ((value & ~((1 << bits)-1)) != ~((1 << bits)-1));
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}
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#ifndef FPU_DEFAULT
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# ifdef TE_LINUX
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# define FPU_DEFAULT FPU_ARCH_FPA
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@ -28089,7 +28098,7 @@ md_apply_fix (fixS * fixP,
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break;
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case BFD_RELOC_THUMB_PCREL_BRANCH9: /* Conditional branch. */
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if ((value & ~0xff) && ((value & ~0xff) != ~0xff))
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if (out_of_range_p (value, 8))
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as_bad_where (fixP->fx_file, fixP->fx_line, BAD_RANGE);
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if (fixP->fx_done || !seg->use_rela_p)
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@ -28101,7 +28110,7 @@ md_apply_fix (fixS * fixP,
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break;
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case BFD_RELOC_THUMB_PCREL_BRANCH12: /* Unconditional branch. */
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if ((value & ~0x7ff) && ((value & ~0x7ff) != ~0x7ff))
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if (out_of_range_p (value, 11))
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as_bad_where (fixP->fx_file, fixP->fx_line, BAD_RANGE);
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if (fixP->fx_done || !seg->use_rela_p)
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@ -28112,6 +28121,7 @@ md_apply_fix (fixS * fixP,
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}
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break;
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/* This relocation is misnamed, it should be BRANCH21. */
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case BFD_RELOC_THUMB_PCREL_BRANCH20:
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if (fixP->fx_addsy
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&& (S_GET_SEGMENT (fixP->fx_addsy) == seg)
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@ -28122,7 +28132,7 @@ md_apply_fix (fixS * fixP,
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/* Force a relocation for a branch 20 bits wide. */
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fixP->fx_done = 0;
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}
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if ((value & ~0x1fffff) && ((value & ~0x0fffff) != ~0x0fffff))
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if (out_of_range_p (value, 20))
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as_bad_where (fixP->fx_file, fixP->fx_line,
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_("conditional branch out of range"));
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@ -28201,12 +28211,11 @@ md_apply_fix (fixS * fixP,
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fixP->fx_r_type = BFD_RELOC_THUMB_PCREL_BRANCH23;
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#endif
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if ((value & ~0x3fffff) && ((value & ~0x3fffff) != ~0x3fffff))
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if (out_of_range_p (value, 22))
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{
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if (!(ARM_CPU_HAS_FEATURE (cpu_variant, arm_ext_v6t2)))
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as_bad_where (fixP->fx_file, fixP->fx_line, BAD_RANGE);
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else if ((value & ~0x1ffffff)
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&& ((value & ~0x1ffffff) != ~0x1ffffff))
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else if (out_of_range_p (value, 24))
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as_bad_where (fixP->fx_file, fixP->fx_line,
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_("Thumb2 branch out of range"));
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}
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@ -28217,7 +28226,7 @@ md_apply_fix (fixS * fixP,
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break;
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case BFD_RELOC_THUMB_PCREL_BRANCH25:
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if ((value & ~0x0ffffff) && ((value & ~0x0ffffff) != ~0x0ffffff))
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if (out_of_range_p (value, 24))
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as_bad_where (fixP->fx_file, fixP->fx_line, BAD_RANGE);
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if (fixP->fx_done || !seg->use_rela_p)
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4
gas/testsuite/gas/arm/pr24991.d
Normal file
4
gas/testsuite/gas/arm/pr24991.d
Normal file
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@ -0,0 +1,4 @@
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#as: -march=armv7-a
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#source: pr24991.s
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#error_output: pr24991.l
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2
gas/testsuite/gas/arm/pr24991.l
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2
gas/testsuite/gas/arm/pr24991.l
Normal file
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@ -0,0 +1,2 @@
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[^:]*: Assembler messages:
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[^:]*:4: Error: conditional branch out of range
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5
gas/testsuite/gas/arm/pr24991.s
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5
gas/testsuite/gas/arm/pr24991.s
Normal file
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@ -0,0 +1,5 @@
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.arch armv7-a
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.syntax unified
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.thumb
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beq .+ 0x124f80
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