[patch] Re: [uml-devel] Kallsyms on UML

[BlaisorBlade <blaisorblade_spam@yahoo.it>]

[-- Attachment #1: Type: text/plain, Size: 2003 bytes --]

Alle 08:01, lunedì 26 luglio 2004, Sonny Rao ha scritto:
> On Mon, Jul 26, 2004 at 10:57:05AM +0700, Mulyadi-Santosa wrote:
> > Hello Sonny
> >
> > >I had one question, I noticed that on stack traces I'm
> > >not getting
> > >symbols even though I had CONFIG_KALLSYMS enabled.  I
> > >looked into it a
> > >bit more and it appears that the kernel build system is

> I was referring to the stack traces which appear after an Oops or
> panic, or if you is simply call dump_stack() somewhere.  Normally, if
> CONFIG_KALLSYMS isn't defined in the kernel's .config file, then those
> stack traces don't show function names, just the address of the
> function, which is somewhat annoying to decode :)

> Fortunately, an in-kernel symbol table has been added in 2.6 which
> does the work for you.  It doesn't seem to work out of the box on UML
> on 2.6, and I was just wondering if it would be trivial to add that
> support to UML.  It seems that way to me, and its a rather useful
> feature for people using UML as a kernel development tool.

Yes, exactly. (It is not matter of EXPORT_SYMBOL, you're right).

You got the right fixes... I've just been working on those ones, and the only 
difference is that I removed the vmlinux -> linux step (with the attached 
patches, the binary to run is vmlinux), to avoid doing again the kallsyms 
trick. Note that to get kallsyms right, you must follow the instructions in 
the main Makefile (which means running it three times which special care).

However, on any 2.6 UML, run cat /dev/kmem (which will panic, the fix is known 
but yet to submit) and say if you can get the stacktrace. For some reason, I 
cannot (even if dump_stack() is invoked); nothing is printed. Seems like the 
printk() are lost (maybe some tricks with bust_spinlock() are needed).

Note: the Set_cflags one is just a cleanup, I send it because without it 
you'll maybe get rejects.
-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729

[-- Attachment #2: uml-Set_cflags_before_arch_Makefile.patch --]
[-- Type: text/x-diff, Size: 2522 bytes --]


If arch/$(ARCH)/Makefile is included before adding -O2 (and the rest) to
CFLAGS, I must duplicate the addition of it to USER_CFLAGS. So let's fix this.
Also, the below code is useless, since if CONFIG_DEBUG_INFO is y, then
CONFIG_FRAME_POINTER is always y.

ifeq ($(CONFIG_DEBUG_INFO),y)
CFLAGS := $(subst -fomit-frame-pointer,,$(CFLAGS))
endif


Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>
---

 uml-linux-2.6.7-paolo/Makefile         |    4 ++--
 uml-linux-2.6.7-paolo/arch/um/Makefile |   21 ---------------------
 2 files changed, 2 insertions(+), 23 deletions(-)

diff -puN Makefile~uml-Set_cflags_before_arch_Makefile Makefile
--- uml-linux-2.6.7/Makefile~uml-Set_cflags_before_arch_Makefile	2004-07-25 15:56:52.676053752 +0200
+++ uml-linux-2.6.7-paolo/Makefile	2004-07-25 15:56:52.680053144 +0200
@@ -447,8 +447,6 @@ else
 include/linux/autoconf.h: ;
 endif
 
-include $(srctree)/arch/$(ARCH)/Makefile
-
 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
 CFLAGS		+= -Os
 else
@@ -466,6 +464,8 @@ endif
 # warn about C99 declaration after statement
 CFLAGS += $(call check_gcc,-Wdeclaration-after-statement,)
 
+include $(srctree)/arch/$(ARCH)/Makefile
+
 #
 # INSTALL_PATH specifies where to place the updated kernel and system map
 # images.  Uncomment if you want to place them anywhere other than root.
diff -puN arch/um/Makefile~uml-Set_cflags_before_arch_Makefile arch/um/Makefile
--- uml-linux-2.6.7/arch/um/Makefile~uml-Set_cflags_before_arch_Makefile	2004-07-25 15:56:52.677053600 +0200
+++ uml-linux-2.6.7-paolo/arch/um/Makefile	2004-07-25 15:56:52.680053144 +0200
@@ -13,10 +13,6 @@ OS := $(shell uname -s)
 # EXTRAVERSION...
 MODLIB := $(INSTALL_MOD_PATH)/lib/modules/$(KERNELRELEASE)
 
-ifeq ($(CONFIG_DEBUG_INFO),y)
-CFLAGS := $(subst -fomit-frame-pointer,,$(CFLAGS))
-endif
-
 core-y			+= $(ARCH_DIR)/kernel/		 \
 			   $(ARCH_DIR)/drivers/          \
 			   $(ARCH_DIR)/sys-$(SUBARCH)/
@@ -138,23 +134,6 @@ USER_CFLAGS := $(patsubst -D__KERNEL__,,
 # To get a definition of F_SETSIG
 USER_CFLAGS += -D_GNU_SOURCE
 
-# From main Makefile, these options are set after including the ARCH makefile.
-# So copy them here.
-
-ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
-USER_CFLAGS		+= -Os
-else
-USER_CFLAGS		+= -O2
-endif
-
-ifndef CONFIG_FRAME_POINTER
-USER_CFLAGS		+= -fomit-frame-pointer
-endif
-
-ifdef CONFIG_DEBUG_INFO
-USER_CFLAGS		+= -g
-endif
-
 CLEAN_FILES += linux x.i gmon.out $(ARCH_DIR)/uml.lds.s \
 	$(ARCH_DIR)/dyn_link.ld.s $(ARCH_DIR)/include/uml-config.h \
 	$(GEN_HEADERS)
_

[-- Attachment #3: uml-use-kallsyms.patch --]
[-- Type: text/x-diff, Size: 1773 bytes --]


This patch makes UML use print_symbol when dumping the stack. It is not yet
complete (the i386 version uses the frame pointers to walk the stack, for
instance).

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>
---

 uml-linux-2.6.7-paolo/arch/um/kernel/sysrq.c   |    4 +++-
 uml-linux-2.6.7-paolo/arch/um/kernel/um_arch.c |    6 +++---
 2 files changed, 6 insertions(+), 4 deletions(-)

diff -puN arch/um/kernel/sysrq.c~uml-use-kallsyms arch/um/kernel/sysrq.c
--- uml-linux-2.6.7/arch/um/kernel/sysrq.c~uml-use-kallsyms	2004-07-25 21:53:23.197200256 +0200
+++ uml-linux-2.6.7-paolo/arch/um/kernel/sysrq.c	2004-07-25 21:54:17.627925528 +0200
@@ -6,6 +6,7 @@
 #include "linux/sched.h"
 #include "linux/kernel.h"
 #include "linux/module.h"
+#include "linux/kallsyms.h"
 #include "asm/page.h"
 #include "asm/processor.h"
 #include "sysrq.h"
@@ -26,7 +27,8 @@ void show_trace(unsigned long * stack)
 		if (kernel_text_address(addr)) {
 			if (i && ((i % 6) == 0))
 				printk("\n   ");
-			printk("[<%08lx>] ", addr);
+			printk(" [<%08lx>] ", addr);
+			print_symbol("%s\n", addr);
 			i++;
                 }
         }
diff -puN arch/um/kernel/um_arch.c~uml-use-kallsyms arch/um/kernel/um_arch.c
--- uml-linux-2.6.7/arch/um/kernel/um_arch.c~uml-use-kallsyms	2004-07-25 22:03:19.815500488 +0200
+++ uml-linux-2.6.7-paolo/arch/um/kernel/um_arch.c	2004-07-25 22:06:10.488554240 +0200
@@ -394,9 +394,9 @@ extern int uml_exitcode;
 static int panic_exit(struct notifier_block *self, unsigned long unused1,
 		      void *unused2)
 {
-#ifdef CONFIG_MAGIC_SYSRQ
-	handle_sysrq('p', &current->thread.regs, NULL);
-#endif
+	bust_spinlocks(1);
+	show_regs(&(current->thread.regs));
+	bust_spinlocks(0);
 	uml_exitcode = 1;
 	machine_halt();
 	return(0);
_

[-- Attachment #4: uml-Single_Linking_Step.patch --]
[-- Type: text/x-diff, Size: 7009 bytes --]



Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>
---

 uml-linux-2.6.7-paolo/Makefile               |   25 +++++++---
 uml-linux-2.6.7-paolo/arch/um/Makefile       |   63 ++++++++++++---------------
 uml-linux-2.6.7-paolo/arch/um/Makefile-i386  |    6 --
 uml-linux-2.6.7/arch/um/kernel/vmlinux.lds.S |   11 ----
 4 files changed, 50 insertions(+), 55 deletions(-)

diff -puN arch/um/Makefile~uml-Single_Linking_Step arch/um/Makefile
--- uml-linux-2.6.7/arch/um/Makefile~uml-Single_Linking_Step	2004-07-25 20:44:47.851827848 +0200
+++ uml-linux-2.6.7-paolo/arch/um/Makefile	2004-07-25 20:44:47.857826936 +0200
@@ -27,13 +27,6 @@ ARCH_SYMLINKS = include/asm-um/arch $(AR
 
 GEN_HEADERS += $(ARCH_DIR)/include/task.h $(ARCH_DIR)/include/kern_constants.h
 
-# This target adds dependencies to "prepare". They are defined in the included
-# Makefiles (see Makefile-i386).
-
-.PHONY: sys_prepare
-sys_prepare:
-	@:
-
 MAKEFILE-$(CONFIG_MODE_TT) += Makefile-tt
 MAKEFILE-$(CONFIG_MODE_SKAS) += Makefile-skas
 
@@ -75,14 +68,8 @@ endif
 
 include/linux/version.h: arch/$(ARCH)/Makefile
 
-$(ARCH_DIR)/vmlinux.lds.S :
-	touch $@
-
-prepare: $(ARCH_SYMLINKS) $(SYS_HEADERS) $(GEN_HEADERS)
-
-LDFLAGS_vmlinux = -r
-
-vmlinux: $(ARCH_DIR)/main.o 
+prepare: $(ARCH_SYMLINKS) $(SYS_HEADERS) $(GEN_HEADERS) \
+	 $(ARCH_DIR)/kernel/vmlinux.lds.S $(ARCH_DIR)/main.o
 
 # These aren't in Makefile-tt because they are needed in the !CONFIG_MODE_TT +
 # CONFIG_MODE_SKAS + CONFIG_STATIC_LINK case.
@@ -105,6 +92,10 @@ endif
 endif
 endif
 
+$(ARCH_DIR)/kernel/vmlinux.lds.S :
+	rm -f $@
+	ln -s ../$(LD_SCRIPT-y:.s=.S) $@
+
 CPP_MODE_TT := $(shell [ "$(CONFIG_MODE_TT)" = "y" ] && echo -DMODE_TT)
 CONFIG_KERNEL_STACK_ORDER ?= 2
 STACK_SIZE := $(shell echo $$[ 4096 * (1 << $(CONFIG_KERNEL_STACK_ORDER)) ] )
@@ -114,16 +105,22 @@ AFLAGS_vmlinux.lds.o = $(shell echo -U$(
 	-DELF_FORMAT=\"$(ELF_FORMAT)\" $(CPP_MODE_TT) \
 	-DKERNEL_STACK_SIZE=$(STACK_SIZE))
 
-export AFLAGS_$(LD_SCRIPT-y:.s=).o = $(AFLAGS_vmlinux.lds.o) -P -C -Uum
-
-LD_SCRIPT-y := $(ARCH_DIR)/$(LD_SCRIPT-y)
-
-#$(LD_SCRIPT-y) : $(LD_SCRIPT-y:.s=.S) scripts FORCE
-#	$(call if_changed_dep,as_s_S)
-
-linux: vmlinux $(LD_SCRIPT-y)
-	$(CC) -Wl,-T,$(LD_SCRIPT-y) $(LINK-y) $(LINK_WRAPS) \
-		-o linux $(ARCH_DIR)/main.o vmlinux -L/usr/lib -lutil
+#LD_SCRIPT-y := $(ARCH_DIR)/$(LD_SCRIPT-y)
+#
+#linux: vmlinux $(LD_SCRIPT-y)
+#	$(CC) -Wl,-T,$(LD_SCRIPT-y) $(LINK-y) $(LINK_WRAPS) \
+#		-o linux $(ARCH_DIR)/main.o vmlinux -L/usr/lib -lutil
+
+define cmd_vmlinux__
+	$(CC) $(CFLAGS_vmlinux) $(LINK-y) $(LINK_WRAPS) \
+	$(ARCH_DIR)/main.o $(vmlinux-init-objs) \
+	-Wl,--start-group \
+	$(vmlinux-main-objs) \
+	-Wl,--end-group \
+	-L/usr/lib -lutil \
+	$(vmlinux-special-objs) \
+	-o $@
+endef
 
 USER_CFLAGS := $(patsubst -I%,,$(CFLAGS))
 USER_CFLAGS := $(patsubst -Derrno=kernel_errno,,$(USER_CFLAGS))
@@ -141,7 +138,7 @@ CLEAN_FILES += linux x.i gmon.out $(ARCH
 MRPROPER_FILES += $(SYMLINK_HEADERS) $(ARCH_SYMLINKS) \
 	$(addprefix $(ARCH_DIR)/kernel/,$(KERN_SYMLINKS))
 
-$(ARCH_DIR)/main.o: $(ARCH_DIR)/main.c sys_prepare
+$(ARCH_DIR)/main.o: $(ARCH_DIR)/main.c
 	@ echo '  MAIN    $@'
 	@ $(CC) $(USER_CFLAGS) $(EXTRA_CFLAGS) -c -o $@ $<
 
@@ -182,15 +179,15 @@ $(ARCH_DIR)/include/kern_constants.h : $
 	$(call filechk,gen_header)
 
 $(ARCH_DIR)/util/mk_task $(ARCH_DIR)/util/mk_constants : $(ARCH_DIR)/util \
-	sys_prepare FORCE ;
+	FORCE ;
 
-$(ARCH_DIR)/util: FORCE
+$(ARCH_DIR)/util: $(SYS_DIR)/sc.h FORCE
 	$(Q)$(MAKE) $(build)=$@
 
 export SUBARCH USER_CFLAGS OS 
 
-all: linux
-
-define archhelp
-  echo  '* linux	- Binary kernel image (./linux)'
-endef
+#all: linux
+#
+#define archhelp
+#  echo  '* linux	- Binary kernel image (./linux)'
+#endef
diff -puN Makefile~uml-Single_Linking_Step Makefile
--- uml-linux-2.6.7/Makefile~uml-Single_Linking_Step	2004-07-25 20:44:47.853827544 +0200
+++ uml-linux-2.6.7-paolo/Makefile	2004-07-25 20:44:47.858826784 +0200
@@ -513,20 +513,30 @@ libs-y		:= $(libs-y1) $(libs-y2)
 #       we cannot yet know if we will need to relink vmlinux.
 #	So we descend into init/ inside the rule for vmlinux again.
 head-y += $(HEAD)
-vmlinux-objs := $(head-y) $(init-y) $(core-y) $(libs-y) $(drivers-y) $(net-y)
+# If an arch (like UML) uses its own linking command for vmlinux, supply
+# it everything to avoid it forgetting some objects.
+vmlinux-init-objs := $(head-y) $(init-y)
+vmlinux-main-objs := $(core-y) $(libs-y) $(drivers-y) $(net-y)
+vmlinux-special-objs = $(filter .tmp_kallsyms%,$^)
+# List of dependencies for vmlinux
+vmlinux-objs := $(vmlinux-init-objs) $(vmlinux-main-objs)
 
 quiet_cmd_vmlinux__ = LD      $@
+#Allow UML to use gcc to link vmlinux.
+#The command below is parametrized enough that you will never change it;
+#but if you still want to change it, update every arch accordingly
+#(at least UML, maybe other ones will use it, too).
+ifeq ($(cmd_vmlinux__),)
 define cmd_vmlinux__
-	$(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) $(head-y) $(init-y) \
+	$(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) \
+	$(vmlinux-init-objs) \
 	--start-group \
-	$(core-y) \
-	$(libs-y) \
-	$(drivers-y) \
-	$(net-y) \
+	$(vmlinux-main-objs) \
 	--end-group \
-	$(filter .tmp_kallsyms%,$^) \
+	$(vmlinux-special-objs) \
 	-o $@
 endef
+endif
 
 #	set -e makes the rule exit immediately on error
 
@@ -550,6 +560,7 @@ define rule_vmlinux
 endef
 
 LDFLAGS_vmlinux += -T arch/$(ARCH)/kernel/vmlinux.lds.s
+CFLAGS_vmlinux += -Wl,-T,arch/$(ARCH)/kernel/vmlinux.lds.s
 
 #	Generate section listing all symbols and add it into vmlinux
 #	It's a three stage process:
diff -puN arch/um/Makefile-i386~uml-Single_Linking_Step arch/um/Makefile-i386
--- uml-linux-2.6.7/arch/um/Makefile-i386~uml-Single_Linking_Step	2004-07-25 20:44:47.854827392 +0200
+++ uml-linux-2.6.7-paolo/arch/um/Makefile-i386	2004-07-25 20:44:47.858826784 +0200
@@ -16,8 +16,6 @@ SYS_UTIL_DIR	:= $(ARCH_DIR)/sys-i386/uti
 
 SYS_HEADERS = $(SYS_DIR)/sc.h $(SYS_DIR)/thread.h
 
-sys_prepare: $(SYS_DIR)/sc.h
-
 prepare: $(SYS_HEADERS)
 
 filechk_$(SYS_DIR)/sc.h := $(SYS_UTIL_DIR)/mk_sc
@@ -30,10 +28,10 @@ filechk_$(SYS_DIR)/thread.h := $(SYS_UTI
 $(SYS_DIR)/thread.h: $(SYS_UTIL_DIR)/mk_thread 
 	$(call filechk,$@)
 
-$(SYS_UTIL_DIR)/mk_sc: scripts/basic/fixdep include/config/MARKER FORCE ; 
+$(SYS_UTIL_DIR)/mk_sc: scripts/basic/fixdep include/config/MARKER FORCE
 	$(Q)$(MAKE) $(build)=$(SYS_UTIL_DIR) $@
 
-$(SYS_UTIL_DIR)/mk_thread: $(ARCH_SYMLINKS) $(GEN_HEADERS) sys_prepare FORCE ; 
+$(SYS_UTIL_DIR)/mk_thread: $(ARCH_SYMLINKS) $(GEN_HEADERS) FORCE
 	$(Q)$(MAKE) $(build)=$(SYS_UTIL_DIR) $@
 
 $(SYS_UTIL_DIR): include/asm FORCE
diff -L arch/um/kernel/vmlinux.lds.S -puN arch/um/kernel/vmlinux.lds.S~uml-Single_Linking_Step /dev/null
--- uml-linux-2.6.7/arch/um/kernel/vmlinux.lds.S
+++ /dev/null	1970-01-01 01:00:00.000000000 +0100
@@ -1,11 +0,0 @@
-#include <asm-generic/vmlinux.lds.h>
-	
-OUTPUT_FORMAT(ELF_FORMAT)
-OUTPUT_ARCH(ELF_ARCH)
-ENTRY(_start)
-jiffies = jiffies_64;
-
-SECTIONS
-{
-#include "asm/common.lds.S"
-}
_