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| author | Jan Beulich <jbeulich@suse.com> | 2021-04-26 10:41:35 +0200 |
|---|---|---|
| committer | Jan Beulich <jbeulich@suse.com> | 2021-04-26 10:41:35 +0200 |
| commit | a7664973b24a242cd9ea17deb5eaf503065fc0bd (patch) | |
| tree | 4022b58da916ab136085e8e19bbaf812e438a678 /ld/testsuite/ld-i386 | |
| parent | 8fb8824599f37a726685197a1728e92bc7a953e5 (diff) | |
| download | binutils-gdb-a7664973b24a242cd9ea17deb5eaf503065fc0bd.tar.gz | |
x86: correct overflow checking for 16-bit PC-relative relocs
The only insn requiring a truly 16-bit PC-relative relocation outside of
16-bit mode is XBEGIN (with an operand size override). For it, the
relocation generated should behave similar to 8- and (for 64-bit) 32-bit
PC-relatives ones, i.e. be checked for a signed value to fit the field.
This same mode is also correct for 16-bit code. Outside of 16-bit code,
branches with operand size overrides act in a truly PC-relative way only
when living in the low 32k of address space, as they truncate rIP to 16
bits. This can't be expressed by a PC-relative relocation.
Putting in place a new testcase, I'd like to note that the two existing
ones (pcrel16 and pcrel16abs) appear to be pretty pointless: They don't
expect any error despite supposedly checking for overflow, and in fact
there can't possibly be any error for the
- former since gas doesn't emit any relocation in the first place there,
- latter because the way the relocation gets expressed by gas doesn't
allow the linker to notice the overflow; it should be detected by gas
if at all, but see above (an error would be reported here for x86-64
afaict, but this test doesn't get re-used there).
Diffstat (limited to 'ld/testsuite/ld-i386')
| -rw-r--r-- | ld/testsuite/ld-i386/i386.exp | 1 | ||||
| -rw-r--r-- | ld/testsuite/ld-i386/pcrel16-2.d | 5 | ||||
| -rw-r--r-- | ld/testsuite/ld-i386/pcrel16-2.s | 12 |
3 files changed, 18 insertions, 0 deletions
diff --git a/ld/testsuite/ld-i386/i386.exp b/ld/testsuite/ld-i386/i386.exp index 6ad69a818f5..d0b3f69fb8d 100644 --- a/ld/testsuite/ld-i386/i386.exp +++ b/ld/testsuite/ld-i386/i386.exp @@ -297,6 +297,7 @@ run_dump_test "abs" run_dump_test "pcrel8" run_dump_test "pcrel16" run_dump_test "pcrel16abs" +run_dump_test "pcrel16-2" run_dump_test "alloc" run_dump_test "warn1" run_dump_test "tlsgd2" diff --git a/ld/testsuite/ld-i386/pcrel16-2.d b/ld/testsuite/ld-i386/pcrel16-2.d new file mode 100644 index 00000000000..c1c340fc75c --- /dev/null +++ b/ld/testsuite/ld-i386/pcrel16-2.d @@ -0,0 +1,5 @@ +#name: PCREL16 overflow (2) +#as: --32 +#ld: -melf_i386 +#error: .*relocation truncated to fit: R_386_PC16 .*t16.* +#error: .*relocation truncated to fit: R_386_PC16 .*_start.* diff --git a/ld/testsuite/ld-i386/pcrel16-2.s b/ld/testsuite/ld-i386/pcrel16-2.s new file mode 100644 index 00000000000..2e974175ae8 --- /dev/null +++ b/ld/testsuite/ld-i386/pcrel16-2.s @@ -0,0 +1,12 @@ + .text + .global _start +_start: + data16 xbegin t16 + ret + + .fill 0x8000,1,0xcc + + .global t16 +t16: + data16 xbegin _start + ret |