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PIC glue assembly code for i386 (untested)
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Jonah Beckford committed Jan 12, 2022
1 parent 284834d commit 4b2db0c
Showing 1 changed file with 104 additions and 27 deletions.
131 changes: 104 additions & 27 deletions runtime/i386.S
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Expand Up @@ -78,6 +78,34 @@
#define CFI_ADJUST(n)
#endif

/* PIC-friendly macro to get the address of the global variable Caml_state and set it in a register. */
#ifdef __PIC__
#define MOV_CAML_STATE_PTR(label, reg) \
call mov_caml_state_##label /* Push IP register */ ; \
mov_caml_state_##label: \
popl ##reg ; \
addl $_GLOBAL_OFFSET_TABLE_, ##reg ; \
movl Caml_state@GOT(##reg), ##reg
#else
#define MOV_CAML_STATE_PTR(label, reg) \
movl G(Caml_state), ##reg
#endif

/* PIC-friendly macro to call a global function using PLT if PIC */
.macro call_global_func name,label
#ifdef __PIC__
pushl %ebx /* Protect ebx */
call call_\label /* Push IP register */
call_\label:
popl %ebx /* Pop IP register */
addl $_GLOBAL_OFFSET_TABLE_, %ebx /* ebx=GOT on PLT entry */
call \name@PLT
popl %ebx
#else
call G(\name)
#endif
.endm

#if !defined(SYS_mingw) && !defined(SYS_cygwin)
#define STACK_PROBE_SIZE 16384
#endif
Expand Down Expand Up @@ -116,7 +144,7 @@ FUNCTION(caml_call_gc)
CFI_STARTPROC
LBL(caml_call_gc):
/* Record lowest stack address and return address */
movl G(Caml_state), %ebx
MOV_CAML_STATE_PTR(l_caml_call_gc, %ebx)
movl (%esp), %eax
movl %eax, CAML_STATE(last_return_address, %ebx)
leal 4(%esp), %eax
Expand All @@ -139,7 +167,7 @@ LBL(caml_call_gc):
movl %esp, CAML_STATE(gc_regs, %ebx)
/* MacOSX note: 16-alignment of stack preserved at this point */
/* Call the garbage collector */
call G(caml_garbage_collection)
call_global_func caml_garbage_collection, l_caml_call_gc
/* Restore all regs used by the code generator */
popl %eax; CFI_ADJUST(-4)
popl %ebx; CFI_ADJUST(-4)
Expand All @@ -156,7 +184,7 @@ LBL(caml_call_gc):

FUNCTION(caml_alloc1)
CFI_STARTPROC
movl G(Caml_state), %ebx
MOV_CAML_STATE_PTR(l_caml_alloc1, %ebx)
movl CAML_STATE(young_ptr, %ebx), %eax
subl $8, %eax
movl %eax, CAML_STATE(young_ptr, %ebx)
Expand All @@ -168,7 +196,7 @@ FUNCTION(caml_alloc1)

FUNCTION(caml_alloc2)
CFI_STARTPROC
movl G(Caml_state), %ebx
MOV_CAML_STATE_PTR(l_caml_alloc2, %ebx)
movl CAML_STATE(young_ptr, %ebx), %eax
subl $12, %eax
movl %eax, CAML_STATE(young_ptr, %ebx)
Expand All @@ -180,7 +208,7 @@ FUNCTION(caml_alloc2)

FUNCTION(caml_alloc3)
CFI_STARTPROC
movl G(Caml_state), %ebx
MOV_CAML_STATE_PTR(l_caml_alloc3, %ebx)
movl CAML_STATE(young_ptr, %ebx), %eax
subl $16, %eax
movl %eax, CAML_STATE(young_ptr, %ebx)
Expand All @@ -192,7 +220,7 @@ FUNCTION(caml_alloc3)

FUNCTION(caml_allocN)
CFI_STARTPROC
movl G(Caml_state), %ebx
MOV_CAML_STATE_PTR(l_caml_allocN, %ebx)
/* eax = size - Caml_state->young_ptr */
subl CAML_STATE(young_ptr, %ebx), %eax
negl %eax /* eax = Caml_state->young_ptr - size */
Expand All @@ -209,7 +237,7 @@ FUNCTION(caml_c_call)
CFI_STARTPROC
/* Record lowest stack address and return address */
/* ecx and edx are destroyed at C call. Use them as temp. */
movl G(Caml_state), %ecx
MOV_CAML_STATE_PTR(l_caml_c_call, %ecx)
movl (%esp), %edx
movl %edx, CAML_STATE(last_return_address, %ecx)
leal 4(%esp), %edx
Expand All @@ -228,37 +256,76 @@ FUNCTION(caml_c_call)

/* Start the OCaml program */

FUNCTION(caml_start_program)
CFI_STARTPROC
/* Save callee-save registers */
pushl %ebx; CFI_ADJUST(4)
pushl %esi; CFI_ADJUST(4)
pushl %edi; CFI_ADJUST(4)
pushl %ebp; CFI_ADJUST(4)
/* Initial entry point is caml_program */
movl $ G(caml_program), %esi
/* Common code for caml_start_program and caml_callback* */
LBL(106):
movl G(Caml_state), %edi
/* Common code for caml_start_program and caml_callback* */
.macro inline_jump_to_caml_header label
MOV_CAML_STATE_PTR(\label, %edi)
/* Build a callback link */
pushl CAML_STATE(gc_regs, %edi); CFI_ADJUST(4)
pushl CAML_STATE(last_return_address, %edi); CFI_ADJUST(4)
pushl CAML_STATE(bottom_of_stack, %edi); CFI_ADJUST(4)
/* Note: 16-alignment preserved on MacOSX at this point */
/* Build an exception handler */
#ifdef __PIC__
pushl %ebx /* Push C = orig(ebx) */
sub $ 4, %esp /* Push B = <tmp> */
call inline_jump_to_caml_exception_\label /* Push IP register */
inline_jump_to_caml_exception_\label:
popl %ebx /* Pop IP register */
addl $_GLOBAL_OFFSET_TABLE_, %ebx
movl LBL(108)@GOT(%ebx), %ebx /* ebx = $ LBL(108) */
pushl %ebx /* Push A = $ LBL(108) */
/* Stack = A, B, C */
movl 8(%esp), %ebx
movl %ebx, 4(%esp) /* Stack = A, C, C */
movl 0(%esp), %ebx
movl %ebx, 8(%esp) /* Stack = A, C, A */
movl 4(%esp), %ebx /* ebx = C = orig(ebx) */
add $ 8, %esp /* Stack = A = $ LBL(108) */
#else
pushl $ LBL(108); CFI_ADJUST(4)
#endif
ALIGN_STACK(8)
pushl CAML_STATE(exception_pointer, %edi); CFI_ADJUST(4)
movl %esp, CAML_STATE(exception_pointer, %edi)
.endm

.macro inline_jump_to_caml_plt label caml_code_funcptr
/* Call the OCaml code */
pushl %ebx /* Protect ebx */
call inline_jump_to_caml_plt_\label /* Push IP register */
inline_jump_to_caml_plt_\label:
popl %ebx /* Pop IP register */
addl $_GLOBAL_OFFSET_TABLE_, %ebx /* ebx=GOT on PLT entry */
call \caml_code_funcptr@PLT
popl %ebx
.endm

FUNCTION(caml_start_program)
CFI_STARTPROC
/* Save callee-save registers */
pushl %ebx; CFI_ADJUST(4)
pushl %esi; CFI_ADJUST(4)
pushl %edi; CFI_ADJUST(4)
pushl %ebp; CFI_ADJUST(4)
/* Initial entry point is caml_program */
#ifdef __PIC__
inline_jump_to_caml_header caml_start_program_initial
inline_jump_to_caml_plt caml_start_program_initial caml_program
#else
movl $ G(caml_program), %esi
#endif
/* Regardless of PIC status, this local label will be used by caml_callback_asm() */
LBL(106):
inline_jump_to_caml_header caml_start_program_106
/* Call the OCaml code */
call *%esi
LBL(107):
movl G(Caml_state), %edi
MOV_CAML_STATE_PTR(l_caml_start_program_107, %edi)
/* Pop the exception handler */
popl CAML_STATE(exception_pointer, %edi); CFI_ADJUST(-4)
addl $12, %esp ; CFI_ADJUST(-12)
LBL(109):
movl G(Caml_state), %edi /* Reload for LBL(109) entry */
MOV_CAML_STATE_PTR(l_caml_start_program_109, %edi) /* Reload for LBL(109) entry */
/* Pop the callback link, restoring the global variables */
popl CAML_STATE(bottom_of_stack, %edi); CFI_ADJUST(-4)
popl CAML_STATE(last_return_address, %edi); CFI_ADJUST(-4)
Expand All @@ -282,7 +349,7 @@ LBL(108):

FUNCTION(caml_raise_exn)
CFI_STARTPROC
movl G(Caml_state), %ebx
MOV_CAML_STATE_PTR(l_caml_raise_exn, %ebx)
testl $1, CAML_STATE(backtrace_active, %ebx)
jne LBL(110)
movl CAML_STATE(exception_pointer, %ebx), %esp
Expand All @@ -299,7 +366,7 @@ LBL(110):
pushl %edx; CFI_ADJUST(4) /* arg 3: sp of raise */
pushl %eax; CFI_ADJUST(4) /* arg 2: pc of raise */
pushl %esi; CFI_ADJUST(4) /* arg 1: exception bucket */
call G(caml_stash_backtrace)
call_global_func caml_stash_backtrace, l_caml_raise_exn
movl %esi, %eax /* Recover exception bucket */
movl %edi, %esp
popl CAML_STATE(exception_pointer, %ebx); CFI_ADJUST(-4)
Expand All @@ -312,7 +379,7 @@ LBL(110):

FUNCTION(caml_raise_exception)
CFI_STARTPROC
movl G(Caml_state), %ebx
MOV_CAML_STATE_PTR(l_caml_raise_exception, %ebx)
testl $1, CAML_STATE(backtrace_active, %ebx)
jne LBL(112)
movl 8(%esp), %eax
Expand All @@ -331,7 +398,7 @@ LBL(112):
pushl CAML_STATE(last_return_address, %ebx); CFI_ADJUST(4)
/* 1: exception bucket */
pushl %esi; CFI_ADJUST(4)
call G(caml_stash_backtrace)
call_global_func caml_stash_backtrace, l_caml_raise_exception
movl %esi, %eax /* Recover exception bucket */
movl CAML_STATE(exception_pointer, %ebx), %esp
popl CAML_STATE(exception_pointer, %ebx); CFI_ADJUST(-4)
Expand Down Expand Up @@ -370,8 +437,13 @@ FUNCTION(caml_callback2_asm)
movl 28(%esp), %edi /* arguments array */
movl 0(%edi), %eax /* arg1: first argument */
movl 4(%edi), %ebx /* arg2: second argument */
#ifdef __PIC__
inline_jump_to_caml_header caml_callback2_asm
inline_jump_to_caml_plt caml_callback2_asm caml_apply2
#else
movl $ G(caml_apply2), %esi /* code pointer */
jmp LBL(106)
#endif
CFI_ENDPROC
ENDFUNCTION(caml_callback2_asm)

Expand All @@ -388,8 +460,13 @@ FUNCTION(caml_callback3_asm)
movl 0(%edi), %eax /* arg1: first argument */
movl 4(%edi), %ebx /* arg2: second argument */
movl 8(%edi), %ecx /* arg3: third argument */
#ifdef __PIC__
inline_jump_to_caml_header caml_callback3_asm
inline_jump_to_caml_plt caml_callback3_asm caml_apply3
#else
movl $ G(caml_apply3), %esi /* code pointer */
jmp LBL(106)
#endif
CFI_ENDPROC
ENDFUNCTION(caml_callback3_asm)

Expand All @@ -405,15 +482,15 @@ FUNCTION(caml_ml_array_bound_error)
ffree %st(6)
ffree %st(7)
/* Record lowest stack address and return address */
movl G(Caml_state), %ebx
MOV_CAML_STATE_PTR(l_caml_ml_array_bound_error, %ebx)
movl (%esp), %edx
movl %edx, CAML_STATE(last_return_address, %ebx)
leal 4(%esp), %edx
movl %edx, CAML_STATE(bottom_of_stack, %ebx)
/* Re-align the stack */
andl $-16, %esp
/* Branch to [caml_array_bound_error] (never returns) */
call G(caml_array_bound_error)
call_global_func caml_array_bound_error, l_caml_ml_array_bound_error
CFI_ENDPROC
ENDFUNCTION(caml_ml_array_bound_error)

Expand Down

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