• Vincent Whitchurch's avatar
    ARM: 8781/1: Fix Thumb-2 syscall return for binutils 2.29+ · afc9f65e
    Vincent Whitchurch authored
    
    
    When building the kernel as Thumb-2 with binutils 2.29 or newer, if the
    assembler has seen the .type directive (via ENDPROC()) for a symbol, it
    automatically handles the setting of the lowest bit when the symbol is
    used with ADR.  The badr macro on the other hand handles this lowest bit
    manually.  This leads to a jump to a wrong address in the wrong state
    in the syscall return path:
    
     Internal error: Oops - undefined instruction: 0 [#2] SMP THUMB2
     Modules linked in:
     CPU: 0 PID: 652 Comm: modprobe Tainted: G      D           4.18.0-rc3+ #8
     PC is at ret_fast_syscall+0x4/0x62
     LR is at sys_brk+0x109/0x128
     pc : [<80101004>]    lr : [<801c8a35>]    psr: 60000013
     Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
     Control: 50c5387d  Table: 9e82006a  DAC: 00000051
     Process modprobe (pid: 652, stack limit = 0x(ptrval))
    
     80101000 <ret_fast_syscall>:
     80101000:       b672            cpsid   i
     80101002:       f8d9 2008       ldr.w   r2, [r9, #8]
     80101006:       f1b2 4ffe       cmp.w   r2, #2130706432 ; 0x7f000000
    
     80101184 <local_restart>:
     80101184:       f8d9 a000       ldr.w   sl, [r9]
     80101188:       e92d 0030       stmdb   sp!, {r4, r5}
     8010118c:       f01a 0ff0       tst.w   sl, #240        ; 0xf0
     80101190:       d117            bne.n   801011c2 <__sys_trace>
     80101192:       46ba            mov     sl, r7
     80101194:       f5ba 7fc8       cmp.w   sl, #400        ; 0x190
     80101198:       bf28            it      cs
     8010119a:       f04f 0a00       movcs.w sl, #0
     8010119e:       f3af 8014       nop.w   {20}
     801011a2:       f2af 1ea2       subw    lr, pc, #418    ; 0x1a2
    
    To fix this, add a new symbol name which doesn't have ENDPROC used on it
    and use that with badr.  We can't remove the badr usage since that would
    would cause breakage with older binutils.
    Signed-off-by: default avatarVincent Whitchurch <vincent.whitchurch@axis.com>
    Signed-off-by: default avatarRussell King <rmk+kernel@armlinux.org.uk>
    afc9f65e
entry-common.S 11.3 KB