poly1305: don't move R13 in sum_arm.s.
Rather than change the value of R13 during the execution, keep R13 fixed
(after the initial prelude) and always use offsets from it.
This should help the runtime figure out what's going on if, say, a
signal should occur while running this code.
I've also trimmed the set of saved registers since Go doesn't require
the callee to maintain anything except R10 and R13.
Change-Id: Ifbeca73c1d964cc43bb7f8c20c61066f22fd562d
Reviewed-on: https://go-review.googlesource.com/31717
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
diff --git a/poly1305/sum_arm.s b/poly1305/sum_arm.s
index 9c3d60f..93167b2 100644
--- a/poly1305/sum_arm.s
+++ b/poly1305/sum_arm.s
@@ -20,10 +20,12 @@
// take care and verify that no synthetic instructions use it.
TEXT poly1305_init_ext_armv6<>(SB), NOSPLIT, $0
- // Needs 32 bytes of stack and 64 bytes of space pointed to by R0.
- // (It might look like it's only 60 bytes of space but the final
- // four bytes will be written by another function.)
- MOVM.DB.W [R4-R11], (R13)
+ // Needs 16 bytes of stack and 64 bytes of space pointed to by R0. (It
+ // might look like it's only 60 bytes of space but the final four bytes
+ // will be written by another function.) We need to skip over four
+ // bytes of stack because that's saving the value of 'g'.
+ ADD $4, R13, R8
+ MOVM.IB [R4-R7], (R8)
MOVM.IA.W (R1), [R2-R5]
MOVW $poly1305_init_constants_armv6<>(SB), R7
MOVW R2, R8
@@ -49,7 +51,8 @@
MOVM.IA.W [R2-R6], (R0)
MOVM.IA.W (R1), [R2-R5]
MOVM.IA [R2-R6], (R0)
- MOVM.IA.W (R13), [R4-R11]
+ ADD $20, R13, R0
+ MOVM.DA (R0), [R4-R7]
RET
#define MOVW_UNALIGNED(Rsrc, Rdst, Rtmp, offset) \
@@ -63,29 +66,34 @@
MOVBU Rtmp, (offset+3)(Rdst)
TEXT poly1305_blocks_armv6<>(SB), NOSPLIT, $0
- // Needs 36 + 128 bytes of stack.
- MOVM.DB.W [R4, R5, R6, R7, R8, R9, g, R11, R14], (R13)
- SUB $128, R13
- MOVW R0, 36(R13)
- MOVW R1, 40(R13)
- MOVW R2, 44(R13)
- MOVW R1, R14
- MOVW R2, R12
- MOVW 56(R0), R8
- WORD $0xe1180008 // TST R8, R8 not working see issue 5921
- EOR R6, R6, R6
- MOVW.EQ $(1<<24), R6
- MOVW R6, 32(R13)
- ADD $64, R13, g
- MOVM.IA (R0), [R0-R9]
- MOVM.IA [R0-R4], (g)
- CMP $16, R12
- BLO poly1305_blocks_armv6_done
+ // Needs 24 bytes of stack for saved registers and then 88 bytes of
+ // scratch space after that. We assume that 24 bytes at (R13) have
+ // already been used: four bytes for the link register saved in the
+ // prelude of poly1305_auth_armv6, four bytes for saving the value of g
+ // in that function and 16 bytes of scratch space used around
+ // poly1305_finish_ext_armv6_skip1.
+ ADD $24, R13, R12
+ MOVM.IB [R4-R8, R14], (R12)
+ MOVW R0, 88(R13)
+ MOVW R1, 92(R13)
+ MOVW R2, 96(R13)
+ MOVW R1, R14
+ MOVW R2, R12
+ MOVW 56(R0), R8
+ WORD $0xe1180008 // TST R8, R8 not working see issue 5921
+ EOR R6, R6, R6
+ MOVW.EQ $(1<<24), R6
+ MOVW R6, 84(R13)
+ ADD $116, R13, g
+ MOVM.IA (R0), [R0-R9]
+ MOVM.IA [R0-R4], (g)
+ CMP $16, R12
+ BLO poly1305_blocks_armv6_done
poly1305_blocks_armv6_mainloop:
WORD $0xe31e0003 // TST R14, #3 not working see issue 5921
BEQ poly1305_blocks_armv6_mainloop_aligned
- ADD $48, R13, g
+ ADD $100, R13, g
MOVW_UNALIGNED(R14, g, R0, 0)
MOVW_UNALIGNED(R14, g, R0, 4)
MOVW_UNALIGNED(R14, g, R0, 8)
@@ -101,21 +109,21 @@
MOVW R0>>26, g
MOVW R1>>20, R11
MOVW R2>>14, R12
- MOVW R14, 40(R13)
+ MOVW R14, 92(R13)
MOVW R3>>8, R4
ORR R1<<6, g, g
ORR R2<<12, R11, R11
ORR R3<<18, R12, R12
BIC $0xfc000000, R0, R0
BIC $0xfc000000, g, g
- MOVW 32(R13), R3
+ MOVW 84(R13), R3
BIC $0xfc000000, R11, R11
BIC $0xfc000000, R12, R12
ADD R0, R5, R5
ADD g, R6, R6
ORR R3, R4, R4
ADD R11, R7, R7
- ADD $64, R13, R14
+ ADD $116, R13, R14
ADD R12, R8, R8
ADD R4, R9, R9
MOVM.IA (R14), [R0-R4]
@@ -131,10 +139,10 @@
MULALU R0, R8, (R14, R12)
MULALU R0, R9, (R11, g)
MULALU R4, R9, (R14, R12)
- MOVW g, 24(R13)
- MOVW R11, 28(R13)
- MOVW R12, 16(R13)
- MOVW R14, 20(R13)
+ MOVW g, 76(R13)
+ MOVW R11, 80(R13)
+ MOVW R12, 68(R13)
+ MOVW R14, 72(R13)
MULLU R2, R5, (R11, g)
MULLU R1, R5, (R14, R12)
MULALU R1, R6, (R11, g)
@@ -147,16 +155,17 @@
MULALU R3, R8, (R14, R12)
MULALU R3, R9, (R11, g)
MULALU R2, R9, (R14, R12)
- MOVW g, 8(R13)
- MOVW R11, 12(R13)
- MOVW R12, 0(R13)
- MOVW R14, w+4(SP)
+ MOVW g, 60(R13)
+ MOVW R11, 64(R13)
+ MOVW R12, 52(R13)
+ MOVW R14, 56(R13)
MULLU R0, R5, (R11, g)
MULALU R4, R6, (R11, g)
MULALU R3, R7, (R11, g)
MULALU R2, R8, (R11, g)
MULALU R1, R9, (R11, g)
- MOVM.IA (R13), [R0-R7]
+ ADD $52, R13, R0
+ MOVM.IA (R0), [R0-R7]
MOVW g>>26, R12
MOVW R4>>26, R14
ORR R11<<6, R12, R12
@@ -187,23 +196,23 @@
MOVW R4>>26, R12
BIC $0xfc000000, R4, R8
ADD R12, R6, R9
- MOVW w+44(SP), R12
- MOVW w+40(SP), R14
+ MOVW 96(R13), R12
+ MOVW 92(R13), R14
MOVW R0, R6
CMP $32, R12
SUB $16, R12, R12
- MOVW R12, 44(R13)
+ MOVW R12, 96(R13)
BHS poly1305_blocks_armv6_mainloop
poly1305_blocks_armv6_done:
- MOVW 36(R13), R12
- MOVW R5, 20(R12)
- MOVW R6, 24(R12)
- MOVW R7, 28(R12)
- MOVW R8, 32(R12)
- MOVW R9, 36(R12)
- ADD $128, R13, R13
- MOVM.IA.W (R13), [R4, R5, R6, R7, R8, R9, g, R11, R14]
+ MOVW 88(R13), R12
+ MOVW R5, 20(R12)
+ MOVW R6, 24(R12)
+ MOVW R7, 28(R12)
+ MOVW R8, 32(R12)
+ MOVW R9, 36(R12)
+ ADD $48, R13, R0
+ MOVM.DA (R0), [R4-R8, R14]
RET
#define MOVHUP_UNALIGNED(Rsrc, Rdst, Rtmp) \
@@ -216,26 +225,76 @@
MOVHUP_UNALIGNED(Rsrc, Rdst, Rtmp); \
MOVHUP_UNALIGNED(Rsrc, Rdst, Rtmp)
-TEXT poly1305_finish_ext_armv6<>(SB), NOSPLIT, $0
- // Needs 36 + 16 bytes of stack.
- MOVM.DB.W [R4, R5, R6, R7, R8, R9, g, R11, R14], (R13)
- SUB $16, R13, R13
- MOVW R0, R5
- MOVW R1, R6
- MOVW R2, R7
- MOVW R3, R8
- AND.S R2, R2, R2
- BEQ poly1305_finish_ext_armv6_noremaining
- EOR R0, R0
- MOVW R13, R9
- MOVW R0, 0(R13)
- MOVW R0, 4(R13)
- MOVW R0, 8(R13)
- MOVW R0, 12(R13)
- WORD $0xe3110003 // TST R1, #3 not working see issue 5921
- BEQ poly1305_finish_ext_armv6_aligned
- WORD $0xe3120008 // TST R2, #8 not working see issue 5921
- BEQ poly1305_finish_ext_armv6_skip8
+// func poly1305_auth_armv6(out *[16]byte, m *byte, mlen uint32, key *[32]key)
+TEXT ·poly1305_auth_armv6(SB), $196-16
+ // The value 196, just above, is the sum of 64 (the size of the context
+ // structure) and 132 (the amount of stack needed).
+ //
+ // At this point, the stack pointer (R13) has been moved down. It
+ // points to the saved link register and there's 196 bytes of free
+ // space above it.
+ //
+ // The stack for this function looks like:
+ //
+ // +---------------------
+ // |
+ // | 64 bytes of context structure
+ // |
+ // +---------------------
+ // |
+ // | 112 bytes for poly1305_blocks_armv6
+ // |
+ // +---------------------
+ // | 16 bytes of final block, constructed at
+ // | poly1305_finish_ext_armv6_skip8
+ // +---------------------
+ // | four bytes of saved 'g'
+ // +---------------------
+ // | lr, saved by prelude <- R13 points here
+ // +---------------------
+ MOVW g, 4(R13)
+
+ MOVW out+0(FP), R4
+ MOVW m+4(FP), R5
+ MOVW mlen+8(FP), R6
+ MOVW key+12(FP), R7
+
+ ADD $136, R13, R0 // 136 = 4 + 4 + 16 + 112
+ MOVW R7, R1
+
+ // poly1305_init_ext_armv6 will write to the stack from R13+4, but
+ // that's ok because none of the other values have been written yet.
+ BL poly1305_init_ext_armv6<>(SB)
+ BIC.S $15, R6, R2
+ BEQ poly1305_auth_armv6_noblocks
+ ADD $136, R13, R0
+ MOVW R5, R1
+ ADD R2, R5, R5
+ SUB R2, R6, R6
+ BL poly1305_blocks_armv6<>(SB)
+
+poly1305_auth_armv6_noblocks:
+ ADD $136, R13, R0
+ MOVW R5, R1
+ MOVW R6, R2
+ MOVW R4, R3
+
+ MOVW R0, R5
+ MOVW R1, R6
+ MOVW R2, R7
+ MOVW R3, R8
+ AND.S R2, R2, R2
+ BEQ poly1305_finish_ext_armv6_noremaining
+ EOR R0, R0
+ ADD $8, R13, R9 // 8 = offset to 16 byte scratch space
+ MOVW R0, (R9)
+ MOVW R0, 4(R9)
+ MOVW R0, 8(R9)
+ MOVW R0, 12(R9)
+ WORD $0xe3110003 // TST R1, #3 not working see issue 5921
+ BEQ poly1305_finish_ext_armv6_aligned
+ WORD $0xe3120008 // TST R2, #8 not working see issue 5921
+ BEQ poly1305_finish_ext_armv6_skip8
MOVWP_UNALIGNED(R1, R9, g)
MOVWP_UNALIGNED(R1, R9, g)
@@ -279,7 +338,7 @@
MOVBU R11, 0(R9)
MOVW R11, 56(R5)
MOVW R5, R0
- MOVW R13, R1
+ ADD $8, R13, R1
MOVW $16, R2
BL poly1305_blocks_armv6<>(SB)
@@ -318,14 +377,14 @@
MOVW $-(1<<26), R12
ADD R11>>26, R12, R12
BIC $0xfc000000, R11, R11
- ADD R12, R4, R14
- MOVW R14>>31, R12
+ ADD R12, R4, R9
+ MOVW R9>>31, R12
SUB $1, R12
AND R12, R6, R6
AND R12, R7, R7
AND R12, g, g
AND R12, R11, R11
- AND R12, R14, R14
+ AND R12, R9, R9
MVN R12, R12
AND R12, R0, R0
AND R12, R1, R1
@@ -336,7 +395,7 @@
ORR R7, R1, R1
ORR g, R2, R2
ORR R11, R3, R3
- ORR R14, R4, R4
+ ORR R9, R4, R4
ORR R1<<26, R0, R0
MOVW R1>>6, R1
ORR R2<<20, R1, R1
@@ -364,53 +423,5 @@
EOR R7, R7, R7
MOVM.IA.W [R0-R7], (R12)
MOVM.IA [R0-R7], (R12)
- ADD $16, R13, R13
- MOVM.IA.W (R13), [R4, R5, R6, R7, R8, R9, g, R11, R14]
- RET
-
-// func poly1305_auth_armv6(out *[16]byte, m *byte, mlen uint32, key *[32]key)
-TEXT ·poly1305_auth_armv6(SB), $228-16
- // The value 228, just above, is the sum of 64 (the size of the context
- // structure) and 164 (the amount of stack that |poly1305_blocks_armv6|
- // needs).
- //
- // At this point, the stack pointer (R13) has been moved down. It
- // points to the saved link register and there's 228 bytes of free
- // space above it.
- MOVW out+0(FP), R4
- MOVW m+4(FP), R5
- MOVW mlen+8(FP), R6
- MOVW key+12(FP), R7
-
- // We need to keep a 64-byte structure on the stack and have enough
- // space for |poly1305_blocks_armv6| (which needs 164 bytes of stack
- // space). This assembly code was written for a C-based world where
- // code just assumes that sufficient stack is available below the
- // current stack pointer. So the structure is kept at the highest
- // addresses of the frame and the stack for other functions exists just
- // below it.
- //
- // (In ARM, R13 points at the value currently at the top of the stack,
- // so the structure address and stack pointer are the same value.)
- //
- // We add 168, not 164, because the link register is saved at *R13.
- ADD $168, R13, R13
- MOVW R13, R0
- MOVW R7, R1
- BL poly1305_init_ext_armv6<>(SB)
- BIC.S $15, R6, R2
- BEQ poly1305_auth_armv6_noblocks
- MOVW R13, R0
- MOVW R5, R1
- ADD R2, R5, R5
- SUB R2, R6, R6
- BL poly1305_blocks_armv6<>(SB)
-
-poly1305_auth_armv6_noblocks:
- MOVW R13, R0
- MOVW R5, R1
- MOVW R6, R2
- MOVW R4, R3
- BL poly1305_finish_ext_armv6<>(SB)
- SUB $168, R13, R13
+ MOVW 4(R13), g
RET
