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Revision 52d7523d84d534c241ebac5ac89f5c0a6cb51e41 authored by EunTaik Lee on 16 February 2016, 04:44:35 UTC, committed by Will Deacon on 19 February 2016, 12:20:37 UTC 
arm64: mm: allow the kernel to handle alignment faults on user accesses
 
Although we don't expect to take alignment faults on access to normal
memory, misbehaving (i.e. buggy) user code can pass MMIO pointers into
system calls, leading to things like get_user accessing device memory.

Rather than OOPS the kernel, allow any exception fixups to run and
return something like -EFAULT back to userspace. This makes the
behaviour more consistent with userspace, even though applications with
access to device mappings can easily cause other issues if they try
hard enough.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Eun Taik Lee <eun.taik.lee@samsung.com>
[will: dropped __kprobes annotation and rewrote commit mesage]
Signed-off-by: Will Deacon <will.deacon@arm.com>
1 parent 8684fa3
Raw File
Kbuild 
#
# Kbuild for top-level directory of the kernel
# This file takes care of the following:
# 1) Generate bounds.h
# 2) Generate timeconst.h
# 3) Generate asm-offsets.h (may need bounds.h and timeconst.h)
# 4) Check for missing system calls

# Default sed regexp - multiline due to syntax constraints
define sed-y
	"/^->/{s:->#\(.*\):/* \1 */:; \
	s:^->\([^ ]*\) [\$$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; \
	s:^->\([^ ]*\) [\$$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; \
	s:->::; p;}"
endef

# Use filechk to avoid rebuilds when a header changes, but the resulting file
# does not
define filechk_offsets
	(set -e; \
	 echo "#ifndef $2"; \
	 echo "#define $2"; \
	 echo "/*"; \
	 echo " * DO NOT MODIFY."; \
	 echo " *"; \
	 echo " * This file was generated by Kbuild"; \
	 echo " */"; \
	 echo ""; \
	 sed -ne $(sed-y); \
	 echo ""; \
	 echo "#endif" )
endef

#####
# 1) Generate bounds.h

bounds-file := include/generated/bounds.h

always  := $(bounds-file)
targets := kernel/bounds.s

# We use internal kbuild rules to avoid the "is up to date" message from make
kernel/bounds.s: kernel/bounds.c FORCE
	$(Q)mkdir -p $(dir $@)
	$(call if_changed_dep,cc_s_c)

$(obj)/$(bounds-file): kernel/bounds.s FORCE
	$(call filechk,offsets,__LINUX_BOUNDS_H__)

#####
# 2) Generate timeconst.h

timeconst-file := include/generated/timeconst.h

targets += $(timeconst-file)

quiet_cmd_gentimeconst = GEN     $@
define cmd_gentimeconst
	(echo $(CONFIG_HZ) | bc -q $< ) > $@
endef
define filechk_gentimeconst
	(echo $(CONFIG_HZ) | bc -q $< )
endef

$(obj)/$(timeconst-file): kernel/time/timeconst.bc FORCE
	$(call filechk,gentimeconst)

#####
# 3) Generate asm-offsets.h
#

offsets-file := include/generated/asm-offsets.h

always  += $(offsets-file)
targets += arch/$(SRCARCH)/kernel/asm-offsets.s

# 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 \
                                      $(obj)/$(timeconst-file) $(obj)/$(bounds-file) FORCE
	$(Q)mkdir -p $(dir $@)
	$(call if_changed_dep,cc_s_c)

$(obj)/$(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE
	$(call filechk,offsets,__ASM_OFFSETS_H__)

#####
# 4) Check for missing system calls
#

always += missing-syscalls
targets += missing-syscalls

quiet_cmd_syscalls = CALL    $<
      cmd_syscalls = $(CONFIG_SHELL) $< $(CC) $(c_flags) $(missing_syscalls_flags)

missing-syscalls: scripts/checksyscalls.sh $(offsets-file) FORCE
	$(call cmd,syscalls)

# Keep these three files during make clean
no-clean-files := $(bounds-file) $(offsets-file) $(timeconst-file)
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