There is currently a problem that U-Boot can not work on ARMv4
because assembly imlementations of memcpy() and some other functions
use "bx lr" instruction that is not available on ARMv4 ("mov pc, lr"
should be used instead).
A working preprocessor-based solution to this problem is found in
arch/arm/lib/relocate.S. Move it to the "ret" macro in
arch/arm/include/asm/assembler.h and change all "bx lr" code
to "ret lr" in functions that may run on ARMv4. Linux source code
deals with this problem in the same manner.
v1 -> v2:
Comment update. Pointed out by Andre Przywara.
Signed-off-by: Sergei Antonov <sap...@gmail.com>
CC: Samuel Holland <sam...@sholland.org>
CC: Ye Li <ye...@nxp.com>
CC: Simon Glass <s...@chromium.org>
CC: Andre Przywara <andre.przyw...@arm.com>
CC: Marek Vasut <ma...@denx.de>
CC: Sean Anderson <sean.ander...@seco.com>
CC: Tom Rini <tr...@konsulko.com>
---
arch/arm/include/asm/assembler.h | 10 ++++++++--
arch/arm/lib/lib1funcs.S | 8 ++++----
arch/arm/lib/memcpy.S | 6 +++---
arch/arm/lib/relocate.S | 10 ++--------
arch/arm/lib/setjmp.S | 4 ++--
5 files changed, 19 insertions(+), 19 deletions(-)
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h
index b14691858601..8d42ef4823e9 100644
--- a/arch/arm/include/asm/assembler.h
+++ b/arch/arm/include/asm/assembler.h
@@ -58,16 +58,22 @@
#endif
/*
- * We only support cores that support at least Thumb-1 and thus we use
- * 'bx lr'
+ * Use 'bx lr' everywhere except ARMv4 (without 'T') where only 'mov pc, lr'
+ * works
*/
.irp c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo
.macro ret\c, reg
+
+ /* ARMv4- don't know bx lr but the assembler fails to see that */
+#ifdef __ARM_ARCH_4__
+ mov\c pc, \reg
+#else
.ifeqs "\reg", "lr"
bx\c \reg
.else
mov\c pc, \reg
.endif
+#endif
.endm
.endr
diff --git a/arch/arm/lib/lib1funcs.S b/arch/arm/lib/lib1funcs.S
index 700eee5fbbe0..7ff4446dd644 100644
--- a/arch/arm/lib/lib1funcs.S
+++ b/arch/arm/lib/lib1funcs.S
@@ -377,7 +377,7 @@ ENTRY(__gnu_thumb1_case_sqi)
lsls r1, r1, #1
add lr, lr, r1
pop {r1}
- bx lr
+ ret lr
ENDPROC(__gnu_thumb1_case_sqi)
.popsection
@@ -391,7 +391,7 @@ ENTRY(__gnu_thumb1_case_uqi)
lsls r1, r1, #1
add lr, lr, r1
pop {r1}
- bx lr
+ ret lr
ENDPROC(__gnu_thumb1_case_uqi)
.popsection
@@ -406,7 +406,7 @@ ENTRY(__gnu_thumb1_case_shi)
lsls r1, r1, #1
add lr, lr, r1
pop {r0, r1}
- bx lr
+ ret lr
ENDPROC(__gnu_thumb1_case_shi)
.popsection
@@ -421,7 +421,7 @@ ENTRY(__gnu_thumb1_case_uhi)
lsls r1, r1, #1
add lr, lr, r1
pop {r0, r1}
- bx lr
+ ret lr
ENDPROC(__gnu_thumb1_case_uhi)
.popsection
#endif
diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S
index eee7a219ce36..a1c996f94ef2 100644
--- a/arch/arm/lib/memcpy.S
+++ b/arch/arm/lib/memcpy.S
@@ -59,7 +59,7 @@
#endif
ENTRY(memcpy)
cmp r0, r1
- bxeq lr
+ reteq lr
enter r4, lr
@@ -148,7 +148,7 @@ ENTRY(memcpy)
str1b r0, ip, cs, abort=21f
exit r4, lr
- bx lr
+ ret lr
9: rsb ip, ip, #4
cmp ip, #2
@@ -258,7 +258,7 @@ ENTRY(memcpy)
.macro copy_abort_end
ldmfd sp!, {r4, lr}
- bx lr
+ ret lr
.endm
ENDPROC(memcpy)
diff --git a/arch/arm/lib/relocate.S b/arch/arm/lib/relocate.S
index 5102bfabde4a..dd6f2e3bd5e0 100644
--- a/arch/arm/lib/relocate.S
+++ b/arch/arm/lib/relocate.S
@@ -61,7 +61,7 @@ ENTRY(relocate_vectors)
stmia r1!, {r2-r8,r10}
#endif
#endif
- bx lr
+ ret lr
ENDPROC(relocate_vectors)
@@ -127,13 +127,7 @@ relocate_done:
mcr p15, 0, r0, c7, c10, 4 /* drain write buffer */
#endif
- /* ARMv4- don't know bx lr but the assembler fails to see that */
-
-#ifdef __ARM_ARCH_4__
- mov pc, lr
-#else
- bx lr
-#endif
+ ret lr
ENDPROC(relocate_code)
diff --git a/arch/arm/lib/setjmp.S b/arch/arm/lib/setjmp.S
index 176a1d5315bf..2f041aeef01c 100644
--- a/arch/arm/lib/setjmp.S
+++ b/arch/arm/lib/setjmp.S
@@ -17,7 +17,7 @@ ENTRY(setjmp)
mov ip, sp
stm a1, {v1-v8, ip, lr}
mov a1, #0
- bx lr
+ ret lr
ENDPROC(setjmp)
.popsection
@@ -31,6 +31,6 @@ ENTRY(longjmp)
bne 1f
mov a1, #1
1:
- bx lr
+ ret lr
ENDPROC(longjmp)
.popsection
--
2.34.1
