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Add vDSO implementations for gettimeofday(), clock_gettime() and
clock_gettime64() kernel syscalls.
Currently those functions are implemented as pure syscall wrappers.
Signed-off-by: Helge Deller <[email protected]>
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Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:
src := $(obj)
When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.
This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.
To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.
Going forward, the variables used in Makefiles will have the following
meanings:
$(obj) - directory in the object tree
$(src) - directory in the source tree (changed by this commit)
$(objtree) - the top of the kernel object tree
$(srctree) - the top of the kernel source tree
Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).
Signed-off-by: Masahiro Yamada <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>
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These are generated files. Prefix them with $(obj)/ instead of $(src)/.
Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Helge Deller <[email protected]>
Reviewed-by: Nicolas Schier <[email protected]>
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The build rule for C is unused because 'obj-cvdso32' is not defined
in this Makefile.
If you add a C file into arch/parisc/kernel/vdso32/ in the future,
you can revert this commit. The kernel does not keep unused code.
Signed-off-by: Masahiro Yamada <[email protected]>
Acked-by: Helge Deller <[email protected]>
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Fix those make warnings:
arch/parisc/kernel/vdso32/Makefile:30: FORCE prerequisite is missing
arch/parisc/kernel/vdso64/Makefile:30: FORCE prerequisite is missing
Add the missing FORCE prerequisites for all build targets identified by
"make help".
Fixes: e1f86d7b4b2a5213 ("kbuild: warn if FORCE is missing for if_changed(_dep,_rule) and filechk")
Signed-off-by: Helge Deller <[email protected]>
Cc: <[email protected]> # 5.18+
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Add minimal vDSO support, which provides the signal trampoline helpers,
but none of the userspace syscall helpers like time wrappers.
The big benefit of this vDSO implementation is, that we now don't need
an executeable stack any longer. PA-RISC is one of the last
architectures where an executeable stack was needed in oder to implement
the signal trampolines by putting assembly instructions on the stack
which then gets executed. Instead the kernel will provide the relevant
code in the vDSO page and only put the pointers to the signal
information on the stack.
By dropping the need for executable stacks we avoid running into issues
with applications which want non executable stacks for security reasons.
Additionally, alternative stacks on memory areas without exec
permissions are supported too.
This code is based on an initial implementation by Randolph Chung from 2006:
https://lore.kernel.org/linux-parisc/[email protected]/
I did the porting and lifted the code to current code base. Dave fixed
the unwind code so that gdb and glibc are able to backtrace through the
code. An additional patch to gdb will be pushed upstream by Dave.
Signed-off-by: Helge Deller <[email protected]>
Signed-off-by: Dave Anglin <[email protected]>
Cc: Randolph Chung <[email protected]>
Signed-off-by: Helge Deller <[email protected]>
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