Revision a2ceff5e555e664751bc653a4d9b133efa18c742 authored by Michael Ellerman on 28 March 2008, 08:11:48 UTC, committed by Paul Mackerras on 28 March 2008, 11:51:02 UTC
There is a bug in the powerpc DABR (data access breakpoint) handling, which can result in us missing breakpoints if several threads are trying to break on the same address. The circumstances are that do_page_fault() calls do_dabr(), this clears the DABR (sets it to 0) and sets up the signal which will report to userspace that the DABR was hit. The do_signal() code will restore the DABR value on the way out to userspace. If we reschedule before calling do_signal(), __switch_to() will check the cached DABR value and compare it to the new thread's value, if they match we don't set the DABR in hardware. So if two threads have the same DABR value, and we schedule from one to the other after taking the interrupt for the first thread hitting the DABR, the second thread will run without the DABR set in hardware. The cleanest fix is to move the cache update into set_dabr(), that way we can't forget to do it. Reported-by: Jan Kratochvil <jan.kratochvil@redhat.com> Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Paul Mackerras <paulus@samba.org>
1 parent 5c29934
Kbuild
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
# 1) Generate asm-offsets.h
# 2) Check for missing system calls
#####
# 1) Generate asm-offsets.h
#
offsets-file := include/asm-$(SRCARCH)/asm-offsets.h
always := $(offsets-file)
targets := $(offsets-file)
targets += arch/$(SRCARCH)/kernel/asm-offsets.s
clean-files := $(addprefix $(objtree)/,$(targets))
# Default sed regexp - multiline due to syntax constraints
define sed-y
"/^->/{s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"
endef
# Override default regexp for specific architectures
sed-$(CONFIG_MIPS) := "/^@@@/{s/^@@@//; s/ \#.*\$$//; p;}"
quiet_cmd_offsets = GEN $@
define cmd_offsets
(set -e; \
echo "#ifndef __ASM_OFFSETS_H__"; \
echo "#define __ASM_OFFSETS_H__"; \
echo "/*"; \
echo " * DO NOT MODIFY."; \
echo " *"; \
echo " * This file was generated by Kbuild"; \
echo " *"; \
echo " */"; \
echo ""; \
sed -ne $(sed-y) $<; \
echo ""; \
echo "#endif" ) > $@
endef
# We use internal kbuild rules to avoid the "is up to date" message from make
arch/$(SRCARCH)/kernel/asm-offsets.s: arch/$(SRCARCH)/kernel/asm-offsets.c FORCE
$(Q)mkdir -p $(dir $@)
$(call if_changed_dep,cc_s_c)
$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s Kbuild
$(Q)mkdir -p $(dir $@)
$(call cmd,offsets)
#####
# 2) Check for missing system calls
#
quiet_cmd_syscalls = CALL $<
cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags)
PHONY += missing-syscalls
missing-syscalls: scripts/checksyscalls.sh FORCE
$(call cmd,syscalls)
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