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author | Alan Modra <amodra@gmail.com> | 2005-12-08 11:05:36 +0000 |
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committer | Alan Modra <amodra@gmail.com> | 2005-12-08 11:05:36 +0000 |
commit | a7985d7382642610f87799e271e3854079eba6b2 (patch) | |
tree | 04d12b0edad4524aa7e49174df28bf32e14670d5 /bfd/reloc.c | |
parent | 3950dc3f514d6a60c003565e610c925bc7cf4abf (diff) | |
download | gdb-a7985d7382642610f87799e271e3854079eba6b2.zip gdb-a7985d7382642610f87799e271e3854079eba6b2.tar.gz gdb-a7985d7382642610f87799e271e3854079eba6b2.tar.bz2 |
* reloc.c (enum complain_overflow): Correct comments.
(bfd_check_overflow): Combine complain_overflow_bitfield and
complain_overflow_signed code.
(_bfd_relocate_contents): Likewise.
(bfd_howto_32): Use complain_overflow_dont.
* elf32-d10v.c (elf_d10v_howto_table): Revert 2002-06-17 change.
* bfd-in2.h: Regenerate.
Diffstat (limited to 'bfd/reloc.c')
-rw-r--r-- | bfd/reloc.c | 109 |
1 files changed, 39 insertions, 70 deletions
diff --git a/bfd/reloc.c b/bfd/reloc.c index d964f16..d5277c0 100644 --- a/bfd/reloc.c +++ b/bfd/reloc.c @@ -255,11 +255,12 @@ CODE_FRAGMENT . {* Do not complain on overflow. *} . complain_overflow_dont, . -. {* Complain if the bitfield overflows, whether it is considered -. as signed or unsigned. *} +. {* Complain if the value overflows when considered as a signed +. number one bit larger than the field. ie. A bitfield of N bits +. is allowed to represent -2**n to 2**n-1. *} . complain_overflow_bitfield, . -. {* Complain if the value overflows when considered as signed +. {* Complain if the value overflows when considered as a signed . number. *} . complain_overflow_signed, . @@ -496,14 +497,14 @@ bfd_check_overflow (enum complain_overflow how, bfd_vma fieldmask, addrmask, signmask, ss, a; bfd_reloc_status_type flag = bfd_reloc_ok; - a = relocation; - /* Note: BITSIZE should always be <= ADDRSIZE, but in case it's not, we'll be permissive: extra bits in the field mask will automatically extend the address mask for purposes of the overflow check. */ fieldmask = N_ONES (bitsize); + signmask = ~fieldmask; addrmask = N_ONES (addrsize) | fieldmask; + a = (relocation & addrmask) >> rightshift;; switch (how) { @@ -513,19 +514,8 @@ bfd_check_overflow (enum complain_overflow how, case complain_overflow_signed: /* If any sign bits are set, all sign bits must be set. That is, A must be a valid negative address after shifting. */ - a = (a & addrmask) >> rightshift; signmask = ~ (fieldmask >> 1); - ss = a & signmask; - if (ss != 0 && ss != ((addrmask >> rightshift) & signmask)) - flag = bfd_reloc_overflow; - break; - - case complain_overflow_unsigned: - /* We have an overflow if the address does not fit in the field. */ - a = (a & addrmask) >> rightshift; - if ((a & ~ fieldmask) != 0) - flag = bfd_reloc_overflow; - break; + /* Fall thru */ case complain_overflow_bitfield: /* Bitfields are sometimes signed, sometimes unsigned. We @@ -533,9 +523,14 @@ bfd_check_overflow (enum complain_overflow how, of n bits is allowed to store -2**n to 2**n-1. Thus overflow if the value has some, but not all, bits set outside the field. */ - a >>= rightshift; - ss = a & ~ fieldmask; - if (ss != 0 && ss != (((bfd_vma) -1 >> rightshift) & ~ fieldmask)) + ss = a & signmask; + if (ss != 0 && ss != ((addrmask >> rightshift) & signmask)) + flag = bfd_reloc_overflow; + break; + + case complain_overflow_unsigned: + /* We have an overflow if the address does not fit in the field. */ + if ((a & signmask) != 0) flag = bfd_reloc_overflow; break; @@ -1437,19 +1432,26 @@ _bfd_relocate_contents (reloc_howto_type *howto, the size of an address. For bitfields, all the bits matter. See also bfd_check_overflow. */ fieldmask = N_ONES (howto->bitsize); + signmask = ~fieldmask; addrmask = N_ONES (bfd_arch_bits_per_address (input_bfd)) | fieldmask; - a = relocation; - b = x & howto->src_mask; + a = (relocation & addrmask) >> rightshift; + b = (x & howto->src_mask & addrmask) >> bitpos; switch (howto->complain_on_overflow) { case complain_overflow_signed: - a = (a & addrmask) >> rightshift; - /* If any sign bits are set, all sign bits must be set. That is, A must be a valid negative address after shifting. */ - signmask = ~ (fieldmask >> 1); + signmask = ~(fieldmask >> 1); + /* Fall thru */ + + case complain_overflow_bitfield: + /* Much like the signed check, but for a field one bit + wider. We allow a bitfield to represent numbers in the + range -2**n to 2**n-1, where n is the number of bits in the + field. Note that when bfd_vma is 32 bits, a 32-bit reloc + can't overflow, which is exactly what we want. */ ss = a & signmask; if (ss != 0 && ss != ((addrmask >> rightshift) & signmask)) flag = bfd_reloc_overflow; @@ -1460,12 +1462,11 @@ _bfd_relocate_contents (reloc_howto_type *howto, SRC_MASK has more bits than BITSIZE, we can get into trouble; we would need to verify that B is in range, as we do for A above. */ - signmask = ((~ howto->src_mask) >> 1) & howto->src_mask; + ss = ((~howto->src_mask) >> 1) & howto->src_mask; + ss >>= bitpos; /* Set all the bits above the sign bit. */ - b = (b ^ signmask) - signmask; - - b = (b & addrmask) >> bitpos; + b = (b ^ ss) - ss; /* Now we can do the addition. */ sum = a + b; @@ -1477,11 +1478,14 @@ _bfd_relocate_contents (reloc_howto_type *howto, positive inputs. The test below looks only at the sign bits, and it really just SIGN (A) == SIGN (B) && SIGN (A) != SIGN (SUM) - */ - signmask = (fieldmask >> 1) + 1; - if (((~ (a ^ b)) & (a ^ sum)) & signmask) - flag = bfd_reloc_overflow; + We mask with addrmask here to explicitly allow an address + wrap-around. The Linux kernel relies on it, and it is + the only way to write assembler code which can run when + loaded at a location 0x80000000 away from the location at + which it is linked. */ + if (((~(a ^ b)) & (a ^ sum)) & signmask & addrmask) + flag = bfd_reloc_overflow; break; case complain_overflow_unsigned: @@ -1496,44 +1500,9 @@ _bfd_relocate_contents (reloc_howto_type *howto, separate test, we can check for this by or-ing in the operands when testing for the sum overflowing its final field. */ - a = (a & addrmask) >> rightshift; - b = (b & addrmask) >> bitpos; sum = (a + b) & addrmask; - if ((a | b | sum) & ~ fieldmask) - flag = bfd_reloc_overflow; - - break; - - case complain_overflow_bitfield: - /* Much like the signed check, but for a field one bit - wider, and no trimming inputs with addrmask. We allow a - bitfield to represent numbers in the range -2**n to - 2**n-1, where n is the number of bits in the field. - Note that when bfd_vma is 32 bits, a 32-bit reloc can't - overflow, which is exactly what we want. */ - a >>= rightshift; - - signmask = ~ fieldmask; - ss = a & signmask; - if (ss != 0 && ss != (((bfd_vma) -1 >> rightshift) & signmask)) + if ((a | b | sum) & signmask) flag = bfd_reloc_overflow; - - signmask = ((~ howto->src_mask) >> 1) & howto->src_mask; - b = (b ^ signmask) - signmask; - - b >>= bitpos; - - sum = a + b; - - /* We mask with addrmask here to explicitly allow an address - wrap-around. The Linux kernel relies on it, and it is - the only way to write assembler code which can run when - loaded at a location 0x80000000 away from the location at - which it is linked. */ - signmask = fieldmask + 1; - if (((~ (a ^ b)) & (a ^ sum)) & signmask & addrmask) - flag = bfd_reloc_overflow; - break; default: @@ -4625,7 +4594,7 @@ bfd_reloc_type_lookup (bfd *abfd, bfd_reloc_code_real_type code) } static reloc_howto_type bfd_howto_32 = -HOWTO (0, 00, 2, 32, FALSE, 0, complain_overflow_bitfield, 0, "VRT32", FALSE, 0xffffffff, 0xffffffff, TRUE); +HOWTO (0, 00, 2, 32, FALSE, 0, complain_overflow_dont, 0, "VRT32", FALSE, 0xffffffff, 0xffffffff, TRUE); /* INTERNAL_FUNCTION |