Christophe Leroy wrote:
powerpc is a bit special for VDSO as well as system calls in the
way that it requires setting CR SO bit which cannot be done in C.
Therefore, entry/exit needs to be performed in ASM.
Implementing __arch_get_vdso_data() would clobbers the link register,
requiring the caller to save it. As the ASM calling function already
has to set a stack frame and saves the link register before calling
the C vdso function, retriving the vdso data pointer there is lighter.
Implement __arch_vdso_capable() and:
- When the timebase is used, make it always return true.
- When the RTC clock is used, make it always return false.
<snip>
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
v6:
- Added missing prototypes in asm/vdso/gettimeofday.h for __c_kernel_ functions.
- Using STACK_FRAME_OVERHEAD instead of INT_FRAME_SIZE
- Rebased on powerpc/merge as of 7 Apr 2020
- Fixed build failure with gcc 9
- Added a patch to create asm/vdso/processor.h and more cpu_relax() in it
---
arch/powerpc/Kconfig | 2 +
arch/powerpc/include/asm/clocksource.h | 7 +
arch/powerpc/include/asm/vdso/clocksource.h | 7 +
arch/powerpc/include/asm/vdso/gettimeofday.h | 175 +++++++++++
arch/powerpc/include/asm/vdso/vsyscall.h | 25 ++
arch/powerpc/include/asm/vdso_datapage.h | 40 +--
arch/powerpc/kernel/asm-offsets.c | 49 +---
arch/powerpc/kernel/time.c | 91 +-----
arch/powerpc/kernel/vdso.c | 5 +-
arch/powerpc/kernel/vdso32/Makefile | 32 +-
arch/powerpc/kernel/vdso32/config-fake32.h | 34 +++
arch/powerpc/kernel/vdso32/gettimeofday.S | 291 +------------------
arch/powerpc/kernel/vdso32/vgettimeofday.c | 29 ++
arch/powerpc/kernel/vdso64/Makefile | 23 +-
arch/powerpc/kernel/vdso64/gettimeofday.S | 243 +---------------
arch/powerpc/kernel/vdso64/vgettimeofday.c | 29 ++
16 files changed, 391 insertions(+), 691 deletions(-)
create mode 100644 arch/powerpc/include/asm/clocksource.h
create mode 100644 arch/powerpc/include/asm/vdso/clocksource.h
create mode 100644 arch/powerpc/include/asm/vdso/gettimeofday.h
create mode 100644 arch/powerpc/include/asm/vdso/vsyscall.h
create mode 100644 arch/powerpc/kernel/vdso32/config-fake32.h
create mode 100644 arch/powerpc/kernel/vdso32/vgettimeofday.c
create mode 100644 arch/powerpc/kernel/vdso64/vgettimeofday.c
You should also consider adding -fasynchronous-unwind-tables. For
background, please see:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ba96301ce9be7925cdaee677b1a2ff8eddba9fd4
- Naveen
