https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98618
Bug ID: 98618
Summary: aarch64: oob adrp offset causes relocation truncated
to fit: R_AARCH64_ADR_PREL_PG_HI21
Product: gcc
Version: 8.4.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: nsz at gcc dot gnu.org
Target Milestone: ---
gcc-8 and earlier can generate adrp with out of bounds offset
for hidden and local symbols.
i haven't yet found the change that fixed this in gcc-9.
this affects glibc since
https://sourceware.org/git/?p=glibc.git;a=commit;h=2f056e8a5dd4dc0f075413f931e82cede37d1057
$ cat bug.c
long n;
struct s { long a[100]; };
extern struct s obj __attribute__((visibility("hidden")));
void foo()
{
long *a = obj.a;
a[n - 0x70000000 + 35] = n;
a[0x6ffffdff - n + 35 + 6 + 16 + 3] = n;
}
$ gcc -fPIC -O2 -c bug.c
$ objdump -rd bug.o
bug.o: file format elf64-littleaarch64
Disassembly of section .text:
0000000000000000 <foo>:
0: 90000000 adrp x0, 8 <foo+0x8>
0: R_AARCH64_ADR_GOT_PAGE n
4: 90000002 adrp x2, 0 <obj>
4: R_AARCH64_ADR_PREL_PG_HI21 obj-0x37ffffee8
8: 91000042 add x2, x2, #0x0
8: R_AARCH64_ADD_ABS_LO12_NC obj-0x37ffffee8
c: 90000001 adrp x1, 0 <obj>
c: R_AARCH64_ADR_PREL_PG_HI21 obj+0x37ffff1d8
10: f9400000 ldr x0, [x0]
10: R_AARCH64_LD64_GOT_LO12_NC n
14: 91000021 add x1, x1, #0x0
14: R_AARCH64_ADD_ABS_LO12_NC obj+0x37ffff1d8
18: f9400000 ldr x0, [x0]
1c: cb000fe3 neg x3, x0, lsl #3
20: f8207840 str x0, [x2, x0, lsl #3]
24: f8216860 str x0, [x3, x1]
28: d65f03c0 ret
$ gcc -shared bug.o obj.o
bug.o: In function `foo':
bug.c:(.text+0x4): relocation truncated to fit: R_AARCH64_ADR_PREL_PG_HI21
against symbol `obj' defined in .data section in obj.o
bug.c:(.text+0xc): relocation truncated to fit: R_AARCH64_ADR_PREL_PG_HI21
against symbol `obj' defined in .data section in obj.o
collect2: error: ld returned 1 exit status
