Patchwork [U-Boot,5/7] powerpc: Minimal private libgcc to build on Debian

login
register
mail settings
Submitter Kyle Moffett
Date Feb. 21, 2011, 5:59 p.m.
Message ID <1298311199-18775-6-git-send-email-Kyle.D.Moffett@boeing.com>
Download mbox | patch
Permalink /patch/83917/
State Changes Requested
Headers show

Comments

Kyle Moffett - Feb. 21, 2011, 5:59 p.m.
Standard Debian powerpc and powerpcspe systems only include hard-float
libgcc in their native compilers, which causes scary build warnings when
building U-Boot.

The easiest way to resolve this is to borrow the routines that U-Boot
needs from the Linux kernel (GPLv2-licensed), which has the same issue.

Specifically, the routines are: _ashldi3(), _ashrdi3(), and _lshrdi3().

The Makefile framework was copied from the U-Boot ARM port.

Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com>
---
 arch/powerpc/lib/Makefile   |   28 ++++++++++++++++++++++++-
 arch/powerpc/lib/_ashldi3.S |   45 +++++++++++++++++++++++++++++++++++++++++
 arch/powerpc/lib/_ashrdi3.S |   47 +++++++++++++++++++++++++++++++++++++++++++
 arch/powerpc/lib/_lshrdi3.S |   45 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 164 insertions(+), 1 deletions(-)
 create mode 100644 arch/powerpc/lib/_ashldi3.S
 create mode 100644 arch/powerpc/lib/_ashrdi3.S
 create mode 100644 arch/powerpc/lib/_lshrdi3.S
Wolfgang Denk - Feb. 21, 2011, 9:23 p.m.
Dear Kyle Moffett,

In message <1298311199-18775-6-git-send-email-Kyle.D.Moffett@boeing.com> you wrote:
> Standard Debian powerpc and powerpcspe systems only include hard-float
> libgcc in their native compilers, which causes scary build warnings when
> building U-Boot.
> 
> The easiest way to resolve this is to borrow the routines that U-Boot
> needs from the Linux kernel (GPLv2-licensed), which has the same issue.

Actually the code says "either version 2 of the License, or (at your
option) any later version", as far as I can tell ?


> Specifically, the routines are: _ashldi3(), _ashrdi3(), and _lshrdi3().

We have been building for years on such systems, and I don;t remember
that such issues have been reprted before for Power Architecture
systems (I remember only ARM to have such issues).

How comes this is suddenly popping up now?


Please also follow the rules when copying code from Linux - provide
exact reference; see bullet # 4 at
http://www.denx.de/wiki/view/U-Boot/Patches#Attributing_Code_Copyrights_Sign

Best regards,

Wolfgang Denk
Wolfgang Denk - Feb. 21, 2011, 9:24 p.m.
Dear Kyle Moffett,

In message <1298311199-18775-6-git-send-email-Kyle.D.Moffett@boeing.com> you wrote:
> Standard Debian powerpc and powerpcspe systems only include hard-float
> libgcc in their native compilers, which causes scary build warnings when
> building U-Boot.
> 
> The easiest way to resolve this is to borrow the routines that U-Boot
> needs from the Linux kernel (GPLv2-licensed), which has the same issue.
> 
> Specifically, the routines are: _ashldi3(), _ashrdi3(), and _lshrdi3().
> 
> The Makefile framework was copied from the U-Boot ARM port.
> 
> Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com>

There are also whitespace problems with this patch - there is
trailing whitespace in the assembler code.  Please fix.

Best regards,

Wolfgang Denk
Kyle Moffett - Feb. 21, 2011, 9:31 p.m.
On Feb 21, 2011, at 16:23, Wolfgang Denk wrote:
> In message <1298311199-18775-6-git-send-email-Kyle.D.Moffett@boeing.com> you wrote:
>> Standard Debian powerpc and powerpcspe systems only include hard-float
>> libgcc in their native compilers, which causes scary build warnings when
>> building U-Boot.
>> 
>> The easiest way to resolve this is to borrow the routines that U-Boot
>> needs from the Linux kernel (GPLv2-licensed), which has the same issue.
> 
> Actually the code says "either version 2 of the License, or (at your
> option) any later version", as far as I can tell ?

Ah, sorry, I dropped the "+" in there somehow.  Will fix.


>> Specifically, the routines are: _ashldi3(), _ashrdi3(), and _lshrdi3().
> 
> We have been building for years on such systems, and I don;t remember
> that such issues have been reprted before for Power Architecture
> systems (I remember only ARM to have such issues).

Debian/RedHat used to build "nof" libraries, but they were almost completely unused and several major bugs went unnoticed for a while.  Furthermore, they took a lot of time to build and they basically did not get used.

Eventually it was decided to just remove the "nof" (soft-float) libgcc, etc.

It's not actually fatal right now, because the 3 routines that it pulls from hard-float libgcc don't use floating point (you just get a nasty warning).  The problem is that if somebody were to accidentally use one of the hard-float-based routines in U-Boot I would unexpectedly get indeterminate results instead of compile errors.


> Please also follow the rules when copying code from Linux - provide
> exact reference; see bullet # 4 at
> http://www.denx.de/wiki/view/U-Boot/Patches#Attributing_Code_Copyrights_Sign

Will fix, thanks!

Cheers,
Kyle Moffett

Patch

diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 724d8ee..5733e59 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -23,6 +23,19 @@ 
 
 include $(TOPDIR)/config.mk
 
+## Build a couple of necessary functions into a private libgcc
+LIBGCC	= $(obj)libgcc.o
+GLSOBJS	+= _ashldi3.o
+GLSOBJS	+= _ashrdi3.o
+GLSOBJS	+= _lshrdi3.o
+LGOBJS	:= $(addprefix $(obj),$(GLSOBJS)) \
+	   $(addprefix $(obj),$(GLCOBJS))
+
+## But only build it if the user asked for it
+ifdef USE_PRIVATE_LIBGCC
+TARGETS	+= $(LIBGCC)
+endif
+
 LIB	= $(obj)lib$(ARCH).o
 
 SOBJS-y	+= ppccache.o
@@ -53,9 +66,14 @@  endif
 
 COBJS	+= $(sort $(COBJS-y))
 
-SRCS	:= $(SOBJS-y:.o=.S) $(COBJS-y:.o=.c)
+SRCS	:= $(GLSOBJS:.o=.S) $(GLCOBJS:.o=.c) \
+	   $(SOBJS-y:.o=.S) $(COBJS-y:.o=.c)
 OBJS	:= $(addprefix $(obj),$(SOBJS-y) $(COBJS-y))
 
+TARGETS += $(LIB)
+
+all: $(TARGETS)
+
 $(LIB):	$(obj).depend $(OBJS)
 	@if ! $(CROSS_COMPILE)readelf -S $(OBJS) | grep -q '\.fixup.*PROGBITS';\
 	then \
@@ -65,6 +83,9 @@  $(LIB):	$(obj).depend $(OBJS)
 	fi;
 	$(call cmd_link_o_target, $(OBJS))
 
+$(LIBGCC): $(obj).depend $(LGOBJS)
+	$(call cmd_link_o_target, $(LGOBJS))
+
 #########################################################################
 
 # defines $(obj).depend target
diff --git a/arch/powerpc/lib/_ashldi3.S b/arch/powerpc/lib/_ashldi3.S
new file mode 100644
index 0000000..1835904
--- /dev/null
+++ b/arch/powerpc/lib/_ashldi3.S
@@ -0,0 +1,45 @@ 
+/*
+ * This code was copied from arch/powerpc/kernel/misc_32.S in the Linux
+ * kernel sources.  The file it was copied from is licensed as follows:
+ *
+ * (C) Copyright 1995-1996 Gary Thomas (gdt@linuxppc.org)
+ *
+ * Largely rewritten by Cort Dougan (cort@cs.nmt.edu)
+ * and Paul Mackerras.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ */
+
+#include <ppc_asm.tmpl>
+#include <ppc_defs.h>
+#include <config.h>
+
+/*
+ * Extended precision shifts.
+ *
+ * Updated to be valid for shift counts from 0 to 63 inclusive.
+ * -- Gabriel
+ *
+ * R3/R4 has 64 bit value
+ * R5    has shift count
+ * result in R3/R4
+ *
+ *  ashrdi3: arithmetic right shift (sign propagation)	
+ *  lshrdi3: logical right shift
+ *  ashldi3: left shift
+ */
+	.globl __ashldi3
+__ashldi3:
+	subfic	r6,r5,32
+	slw	r3,r3,r5	# MSW = count > 31 ? 0 : MSW << count
+	addi	r7,r5,32	# could be xori, or addi with -32
+	srw	r6,r4,r6	# t1 = count > 31 ? 0 : LSW >> (32-count)
+	slw	r7,r4,r7	# t2 = count < 32 ? 0 : LSW << (count-32)
+	or	r3,r3,r6	# MSW |= t1
+	slw	r4,r4,r5	# LSW = LSW << count
+	or	r3,r3,r7	# MSW |= t2
+	blr
diff --git a/arch/powerpc/lib/_ashrdi3.S b/arch/powerpc/lib/_ashrdi3.S
new file mode 100644
index 0000000..ff00197
--- /dev/null
+++ b/arch/powerpc/lib/_ashrdi3.S
@@ -0,0 +1,47 @@ 
+/*
+ * This code was copied from arch/powerpc/kernel/misc_32.S in the Linux
+ * kernel sources.  The file it was copied from is licensed as follows:
+ *
+ * (C) Copyright 1995-1996 Gary Thomas (gdt@linuxppc.org)
+ *
+ * Largely rewritten by Cort Dougan (cort@cs.nmt.edu)
+ * and Paul Mackerras.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ */
+
+#include <ppc_asm.tmpl>
+#include <ppc_defs.h>
+#include <config.h>
+
+/*
+ * Extended precision shifts.
+ *
+ * Updated to be valid for shift counts from 0 to 63 inclusive.
+ * -- Gabriel
+ *
+ * R3/R4 has 64 bit value
+ * R5    has shift count
+ * result in R3/R4
+ *
+ *  ashrdi3: arithmetic right shift (sign propagation)	
+ *  lshrdi3: logical right shift
+ *  ashldi3: left shift
+ */
+	.globl __ashrdi3
+__ashrdi3:
+	subfic	r6,r5,32
+	srw	r4,r4,r5	# LSW = count > 31 ? 0 : LSW >> count
+	addi	r7,r5,32	# could be xori, or addi with -32
+	slw	r6,r3,r6	# t1 = count > 31 ? 0 : MSW << (32-count)
+	rlwinm	r8,r7,0,32	# t3 = (count < 32) ? 32 : 0
+	sraw	r7,r3,r7	# t2 = MSW >> (count-32)
+	or	r4,r4,r6	# LSW |= t1
+	slw	r7,r7,r8	# t2 = (count < 32) ? 0 : t2
+	sraw	r3,r3,r5	# MSW = MSW >> count
+	or	r4,r4,r7	# LSW |= t2
+	blr
diff --git a/arch/powerpc/lib/_lshrdi3.S b/arch/powerpc/lib/_lshrdi3.S
new file mode 100644
index 0000000..0dc83cb
--- /dev/null
+++ b/arch/powerpc/lib/_lshrdi3.S
@@ -0,0 +1,45 @@ 
+/*
+ * This code was copied from arch/powerpc/kernel/misc_32.S in the Linux
+ * kernel sources.  The file it was copied from is licensed as follows:
+ *
+ * (C) Copyright 1995-1996 Gary Thomas (gdt@linuxppc.org)
+ *
+ * Largely rewritten by Cort Dougan (cort@cs.nmt.edu)
+ * and Paul Mackerras.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ */
+
+#include <ppc_asm.tmpl>
+#include <ppc_defs.h>
+#include <config.h>
+
+/*
+ * Extended precision shifts.
+ *
+ * Updated to be valid for shift counts from 0 to 63 inclusive.
+ * -- Gabriel
+ *
+ * R3/R4 has 64 bit value
+ * R5    has shift count
+ * result in R3/R4
+ *
+ *  ashrdi3: arithmetic right shift (sign propagation)	
+ *  lshrdi3: logical right shift
+ *  ashldi3: left shift
+ */
+	.globl __lshrdi3
+__lshrdi3:
+	subfic	r6,r5,32
+	srw	r4,r4,r5	# LSW = count > 31 ? 0 : LSW >> count
+	addi	r7,r5,32	# could be xori, or addi with -32
+	slw	r6,r3,r6	# t1 = count > 31 ? 0 : MSW << (32-count)
+	srw	r7,r3,r7	# t2 = count < 32 ? 0 : MSW >> (count-32)
+	or	r4,r4,r6	# LSW |= t1
+	srw	r3,r3,r5	# MSW = MSW >> count
+	or	r4,r4,r7	# LSW |= t2
+	blr