1 .global __cp_begin 2 .hidden __cp_begin 3 .global __cp_end 4 .hidden __cp_end 5 .global __cp_cancel 6 .hidden __cp_cancel 7 .hidden __cancel 8 .global __syscall_cp_asm 9 .hidden __syscall_cp_asm 10 11 #r0: volatile. may be modified during linkage. 12 #r1: stack frame: 16 byte alignment. 13 #r2: tls/thread pointer on pp32 14 #r3,r4: return values, first args 15 #r5-r10: args 16 #r11-r12: volatile. may be modified during linkage 17 #r13: "small data area" pointer 18 #r14 - r30: local vars 19 #r31: local or environment pointer 20 21 #r1, r14-31: belong to the caller, must be saved and restored 22 #r0, r3-r12, ctr, xer: volatile, not preserved 23 #r0,r11,r12: may be altered by cross-module call, 24 #"a func cannot depend on that these regs have the values placed by the caller" 25 26 #the fields CR2,CR2,CR4 of the cond reg must be preserved 27 #LR (link reg) shall contain the funcs return address 28 .text 29 .type __syscall_cp_asm,%function 30 __syscall_cp_asm: 31 # at enter: r3 = pointer to self->cancel, r4: syscall no, r5: first arg, r6: 2nd, r7: 3rd, r8: 4th, r9: 5th, r10: 6th 32 __cp_begin: 33 # r3 holds first argument, its a pointer to self->cancel. 34 # we must compare the dereferenced value with 0 and jump to __cancel if its not 35 36 lwz 0, 0(3) #deref pointer into r0 37 38 cmpwi cr7, 0, 0 #compare r0 with 0, store result in cr7. 39 beq+ cr7, 1f #jump to label 1 if r0 was 0 40 41 b __cp_cancel #else call cancel 42 1: 43 #ok, the cancel flag was not set 44 # syscall: number goes to r0, the rest 3-8 45 mr 0, 4 # put the system call number into r0 46 mr 3, 5 # Shift the arguments: arg1 47 mr 4, 6 # arg2 48 mr 5, 7 # arg3 49 mr 6, 8 # arg4 50 mr 7, 9 # arg5 51 mr 8, 10 # arg6 52 sc 53 __cp_end: 54 bnslr+ # return if no summary overflow. 55 #else negate result. 56 neg 3, 3 57 blr 58 __cp_cancel: 59 b __cancel 60