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/proc/self/auxv for AT_PAGESZ because musl calls _init with no args

Browse Source 
https://github.com/upx/upx/issues/473
	modified:   mipsel.r3000-linux.shlib-init.S
This commit is contained in:
John Reiser
2021-05-07 09:36:07 -07:00
committed by Markus F.X.J. Oberhumer
parent c5cc83d424
commit ad6d73c875
1 changed files with 51 additions and 15 deletions
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src/stub/src/mipsel.r3000-linux.shlib-init.S
+51 -15
View File
@@ -71,7 +71,10 @@ AT_PAGESZ= 6
__NR_Linux = 4000 __NR_Linux = 4000
__NR_exit = 1+ __NR_Linux __NR_exit = 1+ __NR_Linux
__NR_read = 3+ __NR_Linux
__NR_write = 4+ __NR_Linux __NR_write = 4+ __NR_Linux
__NR_open = 5+ __NR_Linux
__NR_close = 6+ __NR_Linux
__NR_mmap64 = 90+ __NR_Linux __NR_mmap64 = 90+ __NR_Linux
__NR_munmap = 91+ __NR_Linux __NR_munmap = 91+ __NR_Linux
__NR_mprotect = 125+ __NR_Linux __NR_mprotect = 125+ __NR_Linux
@@ -104,7 +107,7 @@ DCACHE= 1<<1
#define UNFILTER 0 /* no unfilter for MIPS */ #define UNFILTER 0 /* no unfilter for MIPS */
N_SLOTS= 0 N_SLOTS= 0
sp_frame = 24 * NBPW sp_frame = 26 * NBPW
.macro slot symbol, n .macro slot symbol, n
.ifnb n .ifnb n
N_SLOTS = \n + N_SLOTS N_SLOTS = \n + N_SLOTS
@@ -126,34 +129,67 @@ pb_info= . - 1*NBPW // .long offset({p_info; b_info; compressed data})
slot f_envp slot f_envp
slot f_argv slot f_argv
slot f_argc slot f_argc
slot f_main
slot f_fd
_start: .globl _start // IN: jp= &_start; arg1= argc; arg2= argv; arg3= envp _start: .globl _start // IN: jp= &_start
// If glibc: arg1= argc; arg2= argv; arg3= envp
// But musl: no args!
//// break // for debugging //// break // for debugging
addiu sp,sp,-sp_frame addiu sp,sp,-sp_frame
sw ra,f_my_ra(sp) sw ra,f_my_ra(sp)
sw arg3,f_envp(sp) sw arg3,f_envp(sp)
sw arg2,f_argv(sp) sw arg2,f_argv(sp)
sw arg1,f_argc(sp) sw arg1,f_argc(sp)
sw fp,f_fp(sp)
// Calculate PAGE_MASK li v0,%lo(_start)
0: // Advance envp to auxp subu jp,jp,v0
lw v0,(arg3) addiu jp,jp,%lo(main) // jp= &main
bnez v0,0b sw jp,f_main(sp)
addiu arg3,arg3,NBPW
// Determine PAGE_MASK
bal 0f
move a0,ra
.asciz "/proc/self/auxv"
bad_open:
bad_read:
li v1,1<<PAGE_SHIFT // default
b 9f
negu fp,v1 // PAGE_MASK
BUFLEN= 40*2*NBPW
0:
move a1,zero // O_RDONLY
do_sys __NR_open
bnez a3,bad_open
sw v0,f_fd(sp) // fd
addiu sp,sp,-BUFLEN
li a2,BUFLEN // buflen
move a1,sp // buffer
move a0,v0 // fd
do_sys __NR_read
bltz a3,bad_read
addu a2,sp,v0 // end-of-buffer
move a3,sp // buffer
0: // Find AT_PAGESZ 0: // Find AT_PAGESZ
lw v0,a_type(arg3) beq a3,a2,5f // not found
li v1,1<<PAGE_SHIFT // default value li v1,1<<PAGE_SHIFT // default value
lw v0,a_type(arg3)
beqz v0,5f // AT_NULL beqz v0,5f // AT_NULL
addiu v0,v0,-AT_PAGESZ addiu v0,v0,-AT_PAGESZ
bnez v0,0b bnez v0,0b
addiu arg3,arg3,2*NBPW addiu arg3,arg3,2*NBPW
lw v1,-2*NBPW + a_val(arg3) lw v1,-2*NBPW + a_val(arg3) // non-default value
5: // v1= PAGE_SIZE 5: // v1= PAGE_SIZE
li v0,%lo(_start) addiu sp,sp,BUFLEN
sw fp,f_fp(sp)
subu jp,jp,v0
negu fp,v1 // PAGE_MASK negu fp,v1 // PAGE_MASK
addiu jp,jp,%lo(main) // jp= &main lw a0,f_fd(sp)
do_sys __NR_close
9:
lw jp,f_main(sp)
jalr jp // ra= &f_decompress jalr jp // ra= &f_decompress
nop nop
e_start: e_start:
@@ -256,7 +292,7 @@ lxlzma_retval = lxlzma_srcdone
lw a0,lxlzma_dst(sp) lw a0,lxlzma_dst(sp)
lw a1,lxlzma_dstdone(sp) lw a1,lxlzma_dstdone(sp)
li a2,ICACHE|DCACHE li a2,ICACHE|DCACHE
li v0,__NR_cacheflush; syscall do_sys __NR_cacheflush
lw v0,lxlzma_retval(sp) # return value from decompression lw v0,lxlzma_retval(sp) # return value from decompression
@@ -305,7 +341,7 @@ eof:
subu a1,lxdst,v1 // actual length generated subu a1,lxdst,v1 // actual length generated
sw a1,(lxdstlen) sw a1,(lxdstlen)
li a2,ICACHE|DCACHE li a2,ICACHE|DCACHE
li v0,__NR_cacheflush; syscall do_sys __NR_cacheflush
lw v0,0(sp) lw v0,0(sp)
jr ra jr ra