/*  powerpc64le-linux.elf-fold.S -- linkage to C code to process ELF binary
*
*  This file is part of the UPX executable compressor.
*
*  Copyright (C) Markus Franz Xaver Johannes Oberhumer
*  Copyright (C) Laszlo Molnar
*  Copyright (C) John F. Reiser
*  All Rights Reserved.
*
*  UPX and the UCL library are free software; you can redistribute them
*  and/or modify them under the terms of the GNU General Public License as
*  published by the Free Software Foundation; either version 2 of
*  the License, or (at your option) any later version.
*
*  This program is distributed in the hope that it will be useful,
*  but WITHOUT ANY WARRANTY; without even the implied warranty of
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*  GNU General Public License for more details.
*
*  You should have received a copy of the GNU General Public License
*  along with this program; see the file COPYING.
*  If not, write to the Free Software Foundation, Inc.,
*  59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*  Markus F.X.J. Oberhumer              Laszlo Molnar
*  <markus@oberhumer.com>               <ezerotven+github@gmail.com>
*
*  John F. Reiser
*  <jreiser@users.sourceforge.net>
*/

#if !defined(BIG_ENDIAN)
#error BIG_ENDIAN must be defined as 0 or 1
#endif
// check consistency of  BIG_ENDIAN:   IBM convention for calling external subroutine
#if    BIG_ENDIAN && (!defined(USE_TOC) || !USE_TOC)
#error BIG_ENDIAN && (!defined(USE_TOC) || !USE_TOC)
#endif
// check consistency of !BIG_ENDIAN: Linux convention for calling external subroutine
#if    !BIG_ENDIAN && defined(USE_TOC) && USE_TOC
#error !BIG_ENDIAN && defined(USE_TOC) && USE_TOC
#endif

NBPW= 8  //Number of Bytes Per Word
AL_STK= 0x10  // stack alignment
#include "arch/powerpc/64/ppc_regs.h"
#include "arch/powerpc/64/macros.S"

PATH_MAX= 4096  // /usr/include/linux/limits.h

szElf64_Ehdr= 0x40
szElf64_Phdr= 0x38
e_phnum= 56
AT_NULL= 0

sz_b_info= 12
  sz_unc= 0
  sz_cpr= 4

sz_l_info= 12
sz_p_info= 12

MAP_PRIVATE=   0x02
MAP_FIXED=     0x10

PROT_READ=     0x1

O_RDONLY=       0

OVERHEAD= 2048

// http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.html#REG
// r0        Volatile register used in function prologs
// r1        Stack frame pointer
// r2        TOC pointer
// r3        Volatile parameter and return value register
// r4-r10    Volatile registers used for function parameters
// r11       Volatile register used in calls by pointer and as an
//             environment pointer for languages which require one
// r12       Volatile register used for exception handling and glink code
// r13       Reserved for use as system thread ID
// r14-r31   Nonvolatile registers used for local variables
//
// CR0-CR1   Volatile condition code register fields (CR0 '.' int; CR1 '.' floating)
// CR2-CR4   Nonvolatile condition code register fields
// CR5-CR7   Volatile condition code register fields

// http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi.html#STACK
//SZ_LINK= 6*8  // (sp,cr,lr, tmp.xlc,tmp.ld,save.toc)
//SZ_PSAV= 8*8  // for arg9, arg10, ...; and for spilling a0-a7 if necessary
// The parameter save area shall be allocated by the caller.
// It shall be doubleword aligned, and shall be at least 8 doublewords in length.

// In:
r_exp=   31  // f_exp == &decompress
  r_buf=   30  // Local
r_ADRU=  29  // &base to unmap
r_LENU=  28  // length to unmap
r_fd=    27  // for fd of /proc/self/exe
r_auxv=  26
r_elfa=  25  // original &Elf64_Ehdr of stub
r_ADRX=  24  // compressed input
r_LENX=  23  // total size
r_FLD=   22  // &O_BINFO; overlaps r_pse
  r_PMASK= 20  // page_mask
// Local:
r_pse=   22  // &"/proc/self/exe"; overlaps r_FLD
av_hi=   21
// r_PMASK= 20
av_len=  19
cblk=    18

page_mask: .quad ~0<<16  // default
        .quad 0  // something else?
        b fold_begin

get_page_mask: .globl get_page_mask
        mflr r0  // retaddr
        call 0f; 0: mflr a0
        mtlr r0  // original retaddr
        ld a0,page_mask - 0b(a0)
        ret

Pprotect: .globl Pprotect
        mflr r0; bl 0f; 0: mflr r6; mtlr r0; ld r0,page_mask - 0b(r6)
        andc r0,a0,r0  // offset within page
        sub a0,a0,r0
        add a1,a1,r0
        b mprotect

Psync: .globl Psync  // (addr, len, flags)
        mflr r0; bl 0f; 0: mflr r6; mtlr r0; ld r0,page_mask - 0b(r6)
        andc r0,a0,r0  // offset within page
        sub a0,a0,r0
        add a1,a1,r0

// System calls write() and msync(,,MS_SYNC) should implicitly flush dcache
// over the covered region before doing the write().
// But strange errors were observed, so flush explicitly.
// Same code as for powerpc32, but with larger CACHELINE.
CACHELINE=128
sweep= a3  // temp addr
dlast= a4  // final addr
        add dlast,a0,a1  // addr + len
        addi dlast,dlast,-1  // highest covered addr
        ori sweep,a0,-1+ CACHELINE  // highest addr on initial cache line
fl_loop:
        dcbst  0,sweep  // initiate store (modified) cacheline to memory
        cmpl cr0,sweep,dlast  // did we cover the highest-addressed byte?
        icbi   0,sweep  // discard instructions from cacheline
        addi     sweep,sweep,CACHELINE  // highest addr on next line
        blt  cr0,fl_loop  // not done yet

        sync   // wait for all memory operations to finish
        isync  // discard prefetched instructions (if any)

        b msync

Pmap: .globl Pmap
        mflr r0; bl 0f; 0: mflr r6; mtlr r0; ld r0,page_mask - 0b(r6)
        andc r0,a0,r0  // offset within page
        sub a0,a0,r0
        add a1,a1,r0
        b mmap

Punmap: .globl Punmap
        mflr r0; bl 0f; 0: mflr r6; mtlr r0; ld r0,page_mask - 0b(r6)
        andc r0,a0,r0  // offset within page
        sub a0,a0,r0
        add a1,a1,r0
        b munmap

fold_begin:
////    teq r0,r0  // debugging
        mtctr r0  // # words before argc  FIXME: fragile
        lwz r0,0(r_FLD)  // O_BINFO | is_ptinterp | unmap_all_pages
// r_FLD dead
        slwi r0,r0,3*4
        mtcrf 0x8,r0  // cr4.eq = unmap_all_pages
        call L90
L90a:
L_PFX= 4  // strlen("   =")
L_pse= L90a + L_PFX
        .asciz "   =/proc/self/exe"
        .balign 4
L90:
        mflr r_pse; addi r_pse,r_pse,4  // L_pse
// slide {<<stuff>>,argc,argv,0,env,0,auxv} down with maximum room before strings
        la a1,-NBPW(sp)  // src ready for ldu
    beq cr4,no_buf
        li r0,L_PFX + PATH_MAX
        sub sp,sp,r0
        clrrdi sp,sp,4  // round down to multiple of (1<<4)
no_buf:

0: // copy stuff (upto auxv)
        la a0,-NBPW(sp)  // dst ready for stdu
        la r_auxv,-NBPW(r_auxv)  // &end ready for ldu
0: // copy upto auxv
        ldu  r0,NBPW(a1); cmpld cr7,a1,r_auxv
        stdu r0,NBPW(a0); blt cr7,0b
        la  r_auxv,2*NBPW(a0)  // new &auxv
        stdu r0,NBPW(a0)  // new  env_terminator
0: // copy auxv
        ld   r0,NBPW(a1); cmpldi cr7,r0,AT_NULL
        std  r0,NBPW(a0)
        ldu  r0,2*NBPW(a1)
        stdu r0,2*NBPW(a0); bne cr7,0b
        la av_hi,NBPW(a0)  // tmp end of auxv
    beq cr4,no_pse_env
        subf av_len,r_auxv,av_hi  // length of auxv

        lwz  r0,L90a - L_pse(r_pse)  // "    ="
        la cblk,NBPW(a1)  // original &strings
        stwu r0,NBPW(a0)
        la  r_buf,L_PFX(a0)  // buffer
// r_fd = open("/proc/self/exe", O_RDONLY)
        li a1,O_RDONLY
        mr a0,r_pse  //     "/proc/self/exe"
        call open; mr r_fd,a0
// readlink("/proc/self/exe", buffer, -1+ PATH_MAX)
        li a2,-1+ PATH_MAX
        movr a1,r_buf  // buffer
        movr a0,r_pse  //     "/proc/self/exe"
        call readlink; la a2,-L_PFX(r_buf)  // a0= len; a2= buffer
// r_buf dead
        cmpdi a0,0; bgt 0f  // success
        la a2,L90a - L_pse(r_pse)  // "   =/proc/self/exe"
// r_pse dead
        li a0,L90  - (NBPW+ L90a)  // round_up(NBPW, strlen("/proc/self/exe"))
0:
        addi a0,a0,L_PFX  // len += strlen("   =");
        add a1,a2,a0  // beyond end of path
        mtctr a0
        movr a0,cblk  // old &strings
// cblk dead
        li a2,0
        stbu a2,-1(a0)  // NUL terminate
0: // slide path up
        lbzu r0,-1(a1)
        stbu r0,-1(a0); bdnz 0b
        std a0,-2*NBPW(r_auxv)  // &"   =<<path>>" for env

        clrrdi a0,a0,3  // word align
        xor r0,sp,a1  // parity of length
        xor r0,r0,a0  // length vs destination
        clrldi r0,r0,-4+ 8*NBPW  // keep bottom 4 bits
        sub a0,a0,r0

// slide the rest of the stack up; leave room for fake TOC of .e_entry
        movr a1,av_hi
        li r0,0; stdu r0,-NBPW(a0); stdu r0,-NBPW(a0)
        movr av_hi,a0  // remember location
        sub r_auxv,a0,av_len
0:
        ldu  r0,-NBPW(a1); cmpld cr7,a1,sp
        stdu r0,-NBPW(a0); bgt+ cr7,0b
        movr sp,a0  // FR_02

no_pse_env:
r_reloc= 32 - 1  # used slot in register save area
        la a6,SZ_FRAME + r_reloc*NBPW(sp)  // &reloc [adjacent to argc]
        std r_elfa,0(a6)  // elfaddr

        stdu sp,-(SZ_FRAME+OVERHEAD)(sp)  // FR_01  allocate this frame
        mr a0,r_ADRX  // &b_info
        mr a1,r_LENX  // total_size
        la a2,SZ_FRAME(sp)  // &Elf64_Ehdr temporary space
        mr a3,r_auxv  // &Elf64_auxv_t
        la a4,SZ_FRAME+OVERHEAD + SZ_FRAME+(r_reloc * NBPW)(sp)  // &p_reloc
        std r_elfa,0(a4)
        call upx_main2  // Out: a0= entry
// entry= upx_main2(b_info *a0, total_size a1, Elf64_Ehdr *a2, ELf32_auxv_t *a3,
//      Elf64_Addr *p_reloc)
        la  sp,SZ_FRAME+OVERHEAD(sp)  // FR_01  deallocate this frame
#if USE_TOC  //{
// Sometimes the "entry TOC" is not a TOC, particularly with musl.
        movr r2,av_hi  // default fake TOC
        andi. r0,a0,7; bne cr0,noTOC  // align(TOC) < 8;  [heuristic]
        lwz r0,0(a0); cmplwi r0,0; bne noTOC  // 4GiB <= .func;  an instruction?

        ld r0, SZ_FRAME+(r_reloc * NBPW)(sp)  // base for TOC (incl. PT_INTERP)
        ld r2,NBPW(r3); add r2,r2,r0  // toc
        ld r3,   0(r3); add r3,r3,r0  // .func   NOTE: r3 === a0
noTOC:
        std r3,0(av_hi)  // .func for .e_entry
#endif  //}
        mr r_exp,a0  // save &entry (.entry when BIG_ENDIAN)

p_memsz= 4+4+ 4*NBPW
// Discard pages of compressed data (includes [ADRX,+LENX) )
        //lhz r0,e_type(r_elfa); cmpwi r0,ET_EXEC; bne 1f  // only ET_EXEC
        movr a0,r_elfa; call brk  // also set the brk
1:
        ld a1,p_memsz+szElf64_Phdr+szElf64_Ehdr(r_elfa)  // Phdr[C_TEXT= 1].p_memsz
        movr a0,r_elfa; call munmap  # discard C_TEXT compressed data

    beq cr4,no_map_pse
// first page of /proc/self/exe, to preserve it despite munmap(ADRU, LENU)
        li a5,0  // offset
        movr a4,r_fd
        cmpwi a4,0; blt no_map_pse
        li a3,MAP_PRIVATE
        li a2,PROT_READ
        neg a1,r_PMASK  // PAGE_SIZE
        li a0,0  // kernel chooses where
        call mmap
// close /proc/self/exe
        movr a0,r_fd
        call close
no_map_pse:

AT_NULL= 0  // <elf.h>
a_type= 0
a_val= NBPW
sz_auxv= 2*NBPW

        ld r0,-NBPW(av_hi)  // &hatch
        mtctr r0
        std r_exp,SZ_FRAME + (-1+ 31)*NBPW(sp)  // hatch: "movr r12,r31" for musl 1.1.16

        mr a0,r_ADRU
        mr a1,r_LENU
        li r0,SYS_munmap
        mtlr r_exp  // entry address

//    BIG_ENDIAN: r2 (TOC) already is live (set after return from upx_main2)
// LITTLE_ENDIAN: r2 never is touched
//      ld   2,SZ_FRAME + (-1+  2)*NBPW(sp)
// r3,r4 are a0,a1 which are parameters to munmap()
//      ld  3,SZ_FRAME + (-1+  3)*NBPW(sp)
//      ld  4,SZ_FRAME + (-1+  4)*NBPW(sp)
        ld  5,SZ_FRAME + (-1+  5)*NBPW(sp)
        ld  6,SZ_FRAME + (-1+  6)*NBPW(sp)
        ld  7,SZ_FRAME + (-1+  7)*NBPW(sp)
        ld  8,SZ_FRAME + (-1+  8)*NBPW(sp)
        ld  9,SZ_FRAME + (-1+  9)*NBPW(sp)
        ld 10,SZ_FRAME + (-1+ 10)*NBPW(sp)
        ld 11,SZ_FRAME + (-1+ 11)*NBPW(sp)
        ld 12,SZ_FRAME + (-1+ 12)*NBPW(sp)
        ld 13,SZ_FRAME + (-1+ 13)*NBPW(sp)
        ld 14,SZ_FRAME + (-1+ 14)*NBPW(sp)
        ld 15,SZ_FRAME + (-1+ 15)*NBPW(sp)
        ld 16,SZ_FRAME + (-1+ 16)*NBPW(sp)
        ld 17,SZ_FRAME + (-1+ 17)*NBPW(sp)
        ld 18,SZ_FRAME + (-1+ 18)*NBPW(sp)
        ld 19,SZ_FRAME + (-1+ 19)*NBPW(sp)
        ld 20,SZ_FRAME + (-1+ 20)*NBPW(sp)
        ld 21,SZ_FRAME + (-1+ 21)*NBPW(sp)
        ld 22,SZ_FRAME + (-1+ 22)*NBPW(sp)
        ld 23,SZ_FRAME + (-1+ 23)*NBPW(sp)
        ld 24,SZ_FRAME + (-1+ 24)*NBPW(sp)
        ld 25,SZ_FRAME + (-1+ 25)*NBPW(sp)
        ld 26,SZ_FRAME + (-1+ 26)*NBPW(sp)
        ld 27,SZ_FRAME + (-1+ 27)*NBPW(sp)
        ld 28,SZ_FRAME + (-1+ 28)*NBPW(sp)
        ld 29,SZ_FRAME + (-1+ 29)*NBPW(sp)
        ld 30,SZ_FRAME + (-1+ 30)*NBPW(sp)
        ld 31,SZ_FRAME + (-1+ 31)*NBPW(sp)
        la sp,SZ_FRAME +      32 *NBPW(sp)  // FR_00  deallocate outer frame

        bctr  // goto escape hatch

  section SYSCALLS
    li r0,0x999; teq r0,r0  // detect fall-through into this seciion

SYS_exit=  1
SYS_fork=  2
SYS_read=  3
SYS_write= 4
SYS_open=  5
SYS_close= 6

SYS_brk=       45
SYS_readlink=  85
SYS_mmap=      90
SYS_munmap=    91
SYS_ftruncate= 93
SYS_mprotect= 125
SYS_msync=    144
SYS_openat=   286
SYS_memfd_create= 360

mmap: .globl mmap
        clrldi  a4,a4,32  // truncate fd to 32 bits; kernel is picky?
        li 0,SYS_mmap
sysgo:
        sc
        bns+ no_fail  // 'bns': branch if No Summary[Overflow]
        neg a0,a0  // failure: return -errno (always >[unsigned] PAGE_MASK)
no_fail:
        ret

munmap: .globl munmap
        li 0,SYS_munmap; 5: b 5f
mprotect: .globl mprotect
        li 0,SYS_mprotect; 5: b 5f
msync: .globl msync
        li 0,SYS_msync; 5: b 5f
ftruncate: .globl ftruncate
        li r0,SYS_ftruncate;5: b 5f
exit: .globl exit
        li r0,SYS_exit;     5: b 5f
brk: .globl brk
        li r0,SYS_brk;      5: b 5f
readlink: .globl readlink
        li r0,SYS_readlink; 5: b 5f
write: .globl write
        li r0,SYS_write;    5: b 5f
read: .globl read
        li r0,SYS_read;     5: b 5f
open: .globl open
        li r0,SYS_open;     5: b 5f
openat64: .globl openat64  // alias of openat because this is 64-bit already
openat: .globl openat
        li r0,SYS_openat;   5: b 5f
close: .globl close
        li r0,SYS_close;    5: b sysgo

upxfd_create: .globl upxfd_create // (char *tag, unsigned flags)
        stdu a0,-AL_STK(sp)  // push tag onto aligned stack
0: // try memfd_create
        ld a0,0(sp)  // get tag
        li r0,SYS_memfd_create; sc; bns+ ok_memfd
        // failed syscall returns errno in a0
        cmpwi a0,EINVAL; bne 8f  // unexpected error number
        cmpwi a1,0; beq no_memfd  // memfd_create failed twice
        li a1,0; b 0b  // try again without MFD_EXEC
no_memfd:  // so try /dev/shm
O_RDWR= 2
O_DIRECTORY= 040000  // 0x4000
O_TMPFILE= 020000000  // 0x400000
        mflr r6
               bl 0f; .asciz "/dev/shm"; .balign 4
            0: mflr a0
        mtlr r6
        li a2,0700  // mode
        lis a1,O_TMPFILE>>16
        ori a1,a1,O_RDWR | O_DIRECTORY
        li r0,SYS_open; sc; bns+ ok_memfd  // name, flags, mode
8:
        teq r0,r0  // unexpected errno
ok_memfd:
        addi sp,sp,AL_STK  // toss tag
        ret

__NR_memfd_create= 360
MFD_EXEC= 0x10
EINVAL= 22

memfd_create: .globl memfd_create
        mflr a3
        li a1,MFD_EXEC  // modern clue
mfd_try:
        call 0f; .asciz "upx"; 0:
        mflr a0
SYS_memfd_create= __NR_memfd_create
        li r0,SYS_memfd_create; sc; bns+ 0f  // success
        cmpi cr7,a1,0; bne cr7,1f  // not 2nd time
8:
        teq r0,r0  // 2nd error, or unexpected 1st error
1:
        cmpi cr7,a0,EINVAL; bne cr7,8b  // unexpected 1st error
        li a1,0; b mfd_try  // 2nd attempt
0:
        mtlr a3
        ret

memcpy: .globl memcpy  // (dst, src, n)
        cmpwi a2,0; beq- 9f
        mtctr a2
        subi a3,a0,1
        subi a1,a1,1
0:
        lbzu r0,1(a1)
        stbu r0,1(a3)
        bdnz 0b
9:
        blr  // return original dst

my_bkpt: .globl my_bkpt
        teq r0,r0  // my_bkpt
        blr

/* vim:set ts=8 sw=8 et: */
