Use saved registers for parameters to 'fold'; lzma can clobber others

modified:   arm64-linux.elf-entry.S
	modified:   arm64-linux.elf-fold.S

src/stub/src/arm64-linux.elf-entry.S

@@ -41,6 +41,7 @@ sz_b_info= 12
   b_method= 8
 sz_l_info= 12
 sz_p_info= 12
+sz_o_binfo= 4
 
 PROT_READ=  1
 PROT_WRITE= 2
@@ -70,7 +71,6 @@ mflg:
         .long MFLG  // MAP_{PRIVATE|ANONYMOUS}  // QNX vs linux
         .xword ADRM  // dst  for map
 _start: .globl _start
-    brk #0
 /* Get some pages: enough
    to duplicate the entire compressed PT_LOAD, plus 1 page, located just after
    the brk() of the _un_compressed program.  The address is pre-calculated
@@ -88,23 +88,22 @@ _start: .globl _start
 #endif  /*}*/
 
         adr x12,start_params -4  // &sz_pack2
-        ldp w1,w10,[x12]  // w1= sz_pack2; w10= LENF
+        ldp w26,w10,[x12]  // w1= sz_pack2; w10= LENF
         ldp w11,w13,[x12,#2*4]  // w11= CPRO; w13= MFLG
         add x11,x11,x12  // cpr0
         add x10,x10,x12  // end_decompress
         ldr w3,[x11,# sz_unc]
-        sub x9,x12,x1  // &our_Elf64_Ehdr
+        sub x9,x12,x26  // &our_Elf64_Ehdr
-        add w1,w1,w3  // sz_pack2 + cpr0.sz_unc
+        add w26,w26,w3  // sz_pack2 + cpr0.sz_unc
+        ldr w27,[x11,#o_binfo - cpr0]
+        add x27,x27,x9  // &b_info for Elf64_Ehdr
         ldr x0,[x12,#4*4]  // ADRM
-        add x1,x1,# PAGE_SIZE
+        add w26,w26,# PAGE_SIZE
-  section LUNMP000
-        // unused
-  section LUNMP001
-        // unused
   section ELFMAINXu
-        PUSH4(x0,x1,x2,x13)  // ADRU, LENU, space for sz_unc, MFLG
+        PUSH4(x0,x26,x2,x13)  // ADRU, LENU, space for sz_unc, MFLG
 SP_MFLG= 4*8
 D_sz_unc=2*8  // stack displacement to sz_unc
+        mov w1,w26  // length
         mov w2,#PROT_READ | PROT_WRITE | PROT_EXEC
         orr w3,w13,#MAP_FIXED  // MFLG: MAP_{PRIVATE|ANON}
         mov x5,#0  // offset= 0
@@ -130,18 +129,13 @@ copy_cl:  // copy decompressor and folded code
           sub x5,x9,#64; // FIXME(memcheck) dc cvau,x5  // clean 64-byte line
         blo copy_cl  // all source lines
 
-        sub x4,x0,x9  // relocation amount
         ldr w1,[sp,#SP_MFLG]
-        adr x15,f_decompress
+        sub x4,x0,x9  // relocation amount
         str w1,[x0],#4  // MFLG at -4+ fold_begin
         mov lr,x0  // dst for unfolded code
-        add x15,x15,x4  // relocated f_decompress
+        adr x28,f_decompress
-
+        add x28,x28,x4  // relocated f_decompress
-        ldr w7,o_binfo
+        add x27,x27,x4  // relocated &b_info
-        ldr w9,[x12]  // sz_pack2
-        sub w9,w9,w7
-        sub x10,x12,x9  // &b_info
-        add x10,x10,x4  // relocated &b_info
 
         ldr w4,[x11,# b_method]  // 5th param (whole word: endian issues!)
 D_stm1=0*8
@@ -154,7 +148,7 @@ D_stm1=0*8
 #if DEBUG  /*{*/
         stmdb sp!,{TRACE_REGS}; mov r0,#3; bl trace
 #endif  /*}*/
-        br x15  // decompress folded code, return to *lr
+        br x28  // decompress folded code, return to *lr
 
 #if DEBUG  /*{*/
 TRACE_BUFLEN=512

src/stub/src/arm64-linux.elf-fold.S

@@ -50,6 +50,7 @@ AT_FDCWD= -100
 
 PAGE_SHIFT= 12
 PAGE_SIZE = -(~0<<PAGE_SHIFT)
+PATHMAX= 4096
 
 #ifndef DEBUG  /*{*/
 #define DEBUG 0
@@ -63,9 +64,9 @@ PAGE_SIZE = -(~0<<PAGE_SHIFT)
 
 fold_begin:
 /* In:
-   r15= f_decompress
+   x28= f_decompress
-   r10= &b_info of first compressed block (after move)
+   x27= &b_info of first compressed block (after move)
-    r9= total size of compressed data
+   w26= total size of compressed data
     sp/ ADRU,LENU,sz_unc,MFLG, argc,argv...
 */
         POP4(x3,x4,x5,x8)  // x3= ADRU; x4= LENU; x5= sz_unc; x8= MFLG
@@ -81,7 +82,7 @@ fold_begin:
         ldr x2,[x1],#2*8
         cbnz x2,.L20  // AT_NULL
 
-        sub x0,x1,#4096 // buffer for readlink
+        sub x0,x1,#PATHMAX // buffer for readlink
         sub x0,x0,#4  // space for copy of space3eq
         sub x1,x1,x0  // amount needed for argc,argv,env,auxv
         lsr x0,x0,#PAGE_SHIFT  // round down
@@ -124,7 +125,7 @@ SP_argc= 4*8  // remember the hole from PUSH3
         ldr w2,space3eq
         str w2,[x1],#4  // "   =" of new env var
 
-        mov w2,#4096-1  // buffer length and null terminator
+        mov w2,#PATHMAX-1  // buffer length and null terminator
         adr x0,proc_self_exe
         bl readlink
 /* Preserve symlink /proc/self/exe by mapping one page into stack */
@@ -147,11 +148,11 @@ SP_argc= 4*8  // remember the hole from PUSH3
         add x6,sp,#3*8  // &reloc
           sub sp,sp,#MAX_ELF_HDR + OVERHEAD  // alloca
         adr x5,f_unfilter
-        mov x4,x15  // f_decompress
+        mov x4,x28  // f_decompress
         mov x3,x7  // new &Elf64_auxv_t
         mov x2,sp  // ehdr
-        mov w1,w9  // total size of compressed data
+        mov w1,w26  // total size of compressed data
-        mov x0,x10  // &b_info
+        mov x0,x27  // &b_info
         bl upx_main
           add sp,sp,#MAX_ELF_HDR + OVERHEAD  // un-alloca
         mov lr,x0  // entry address