On 5/8/22 8:55 PM, Dave Marchevsky wrote: > On 5/1/22 3:00 PM, Yonghong Song wrote: >> Currently, the 64bit relocation value in the instruction >> is computed as follows: >> __u64 imm = insn[0].imm + ((__u64)insn[1].imm << 32) >> >> Suppose insn[0].imm = -1 (0xffffffff) and insn[1].imm = 1. >> With the above computation, insn[0].imm will first sign-extend >> to 64bit -1 (0xffffffffFFFFFFFF) and then add 0x1FFFFFFFF, >> producing incorrect value 0xFFFFFFFF. The correct value >> should be 0x1FFFFFFFF. >> >> Changing insn[0].imm to __u32 first will prevent 64bit sign >> extension and fix the issue. >> >> Signed-off-by: Yonghong Song <yhs@xxxxxx> >> --- >> tools/lib/bpf/relo_core.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> > > Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx> > Whoops, meant: Acked-by: Dave Marchevsky <davemarchevsky@xxxxxx>
