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Linux i386 allow compression of position-independent main executables (gcc -pie).

Browse Source 
p_elf.h p_lx_elf.cpp p_lx_elf.h p_lx_exc.cpp
	stub/fold_elf86.asm stub/fold_elf86.h stub/l_lx_elf.c
	stub/l_lx_elf86.asm stub/l_lx_elf86.h stub/l_lx_elf86.lds
	stub/linux.hh

committer: jreiser <jreiser> 1126886896 +0000
This commit is contained in:
John Reiser
2005-09-16 16:08:16 +00:00
parent eb6c51426a
commit 3f7b642c7d
11 changed files with 761 additions and 515 deletions
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src/stub/fold_elf86.asm
+23 -15
View File
@@ -35,6 +35,7 @@
%define PAGE_SIZE ( 1<<12)
%define szElf32_Ehdr 0x34
%define szElf32_Phdr 8*4
%define e_type 16
%define e_entry (16 + 2*2 + 4)
%define p_memsz 5*4
%define szb_info 12
@@ -54,9 +55,6 @@ fold_begin: ; enter: %ebx= &Elf32_Ehdr of this program
; dword sz_uncompressed, sz_compressed
; byte compressed_data...
pop eax ; discard &sz_uncompressed
pop eax ; discard sz_uncompressed
; ld-linux.so.2 depends on AT_PHDR and AT_ENTRY, for instance.
; Move argc,argv,envp down to make room for Elf_auxv table.
; Linux kernel 2.4.2 and earlier give only AT_HWCAP and AT_PLATFORM
@@ -75,6 +73,8 @@ fold_begin: ; enter: %ebx= &Elf32_Ehdr of this program
%define AT_PAGESZ 6
%define AT_ENTRY 9
%define ET_DYN 3
sub ecx, ecx
mov edx, (1<<AT_PHDR) | (1<<AT_PHENT) | (1<<AT_PHNUM) | (1<<AT_PAGESZ) | (1<<AT_ENTRY)
mov esi, esp
@@ -96,21 +96,34 @@ L50:
%define OVERHEAD 2048
%define MAX_ELF_HDR 512
sub esp, dword MAX_ELF_HDR + OVERHEAD ; alloca
mov edx, esp ; %edx= &tmp
push ebx ; save &Elf32_Ehdr of this stub
sub esp, dword MAX_ELF_HDR + OVERHEAD
xor ecx, ecx ; 0
push ecx ; assume not ET_DYN
lea eax, [szElf32_Ehdr + 2*szElf32_Phdr + szl_info + szp_info + ebx] ; 1st &b_info
mov esi, [e_entry + ebx] ; beyond compressed data
cmp word [e_type + ebx], byte ET_DYN
jne L53
pop ecx ; is ET_DYN: discard false assumption
add esi, ebx ; relocate e_entry
mov ch, PAGE_SIZE>>8 ; %ecx= PAGE_SIZE
add ebx, [p_memsz + szElf32_Ehdr + ebx]
add ebx, ecx
push ebx ; dynbase
L53:
sub esi, eax ; length of compressed data
mov ebx, [ eax] ; length of uncompressed ELF headers
mov edx, esp ;
mov ecx, [4+ eax] ; length of compressed ELF headers
add ecx, byte szb_info
pusha ; (AT_table, sz_cpr, f_expand, &tmp_ehdr, {sz_unc, &tmp}, {sz_cpr, &b1st_info} )
inc edi ; swap with above 'pusha' to inhibit auxv_up for PT_INTERP
EXTERN upx_main
call upx_main ; returns entry address
add esp, dword 8*4 + MAX_ELF_HDR + OVERHEAD ; remove 8 params, temp space
add esp, byte 8*4 ; remove 8 params from pusha
pop ecx ; dynbase
pop ebx ; &Elf32_Ehdr of this stub
add esp, dword MAX_ELF_HDR + OVERHEAD ; un-alloca
push eax ; save entry address
dec edi ; auxv table
@@ -127,9 +140,9 @@ L60:
; See bug libc/1165 at http://bugs.gnu.org/cgi-bin/gnatsweb.pl
; Found 1999-06-16 glibc-2.1.1
; Fixed 1999-12-29 glibc-2.1.2
%define N_STKCLR (0x100 + MAX_ELF_HDR + OVERHEAD)/4
%define N_STKCLR 8
;
;%define N_STKCLR (0x100 + MAX_ELF_HDR + OVERHEAD)/4
;%define N_STKCLR 8
; lea edi, [esp - 4*N_STKCLR]
; pusha ; values will be zeroed
; mov esi,esp ; save
@@ -138,7 +151,6 @@ L60:
; ; xor eax,eax ; eax already 0 from L60
; rep stosd
; mov esp,esi ; restore
; xor ecx, ecx ; ecx already 0 from "rep stosd"
push eax
push eax
@@ -148,13 +160,9 @@ L60:
push eax
push eax
push eax ; 32 bytes of zeroes now on stack
push eax
pop ecx ; 0
sub ecx, ebx ; length to unmap
mov al, __NR_munmap ; eax was 0 from L60
mov ch, PAGE_SIZE>>8 ; 0x1000
add ecx, [p_memsz + szElf32_Ehdr + ebx] ; length to unmap
mov bh, 0 ; from 0x401000 to 0x400000
jmp [edi] ; unmap ourselves via escape hatch, then goto entry
; called twice: