Remove remaining executable code from x86-64 vsyscall page
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- v1 Latest5 patches 5 repliesIn review
Patches in v1 No applies recorded yet
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/5 | x86: Make alternative instruction pointers relativearch/ arch/ arch/ +3 more | +31 | 0 replies | |
| 2/5 | x86-64: Allow alternative patching in the vDSOarch/ | +32 | 1 reply | |
| 3/5 | x86-64: Add --no-undefined to vDSO buildarch/ | +1 | 0 replies | |
| 4/5 | clocksource: Replace vread and fsys_mmio with generic arch dataarch/ arch/ arch/ +8 more | +49 | 4 replies | |
| 5/5 | x86-64: Move vread_tsc and vread_hpet into the vDSOarch/ arch/ arch/ +9 more | +56 | 0 replies |
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Cover letter [PATCH 0/5] Remove remaining executable code from x86-64 vsyscall page
After the vsyscall emulation patches, the only real executable code left in the vsyscall page is vread_tsc and vread_hpet. That code is only called from the vDSO, so move it into the vDSO.
The first four patches prepare to move the code.
vread_tsc() uses rdtsc_barrier(), which contains two alternatives. Patch 1 and 2 make alternative patching work in the vDSO. (This has a slightly odd side effect that the vDSO image dumped from memory doesn't quite match the debug version anymore, but it's hard to imagine that causing problems.)
Patch 3 fixes an annoyance I found while writing this code. If you introduce an undefined symbol into the vDSO, you get an unhelpful error message. ld is smart enough to give a nice error if you ask it to.
Patch 4 cleans up the architecture-specific part of struct clocksource. IA64 had its own ifdefed code in there, and the supposedly generic vread pointer was only used by x86-64. With the patch, each arch gets to set up its own private part of struct clocksource.
*** Note to IA64 people: I have not even compile-tested this on IA64. ***
Patch 5 is the meat. It moves vread_tsc and vread_hpet into the vDSO where they belong, and it's a net deletion of code because it removes a bunch of magic needed to make regular functions accessible through the vsyscall page.
With all of these patches applied, every single byte in the vsyscall page is some sort of trap instruction.
This series applies to the x86/vdso branch of the -tip tree.
Andy Lutomirski (5):
x86: Make alternative instruction pointers relative
x86-64: Allow alternative patching in the vDSO
x86-64: Add --no-undefined to vDSO build
clocksource: Replace vread and fsys_mmio with generic arch data
x86-64: Move vread_tsc and vread_hpet into the vDSO
arch/ia64/include/asm/clocksource.h | 16 ++++++++++ arch/ia64/kernel/cyclone.c | 2 +- arch/ia64/kernel/time.c | 2 +- arch/ia64/sn/kernel/sn2/timer.c | 2 +- arch/x86/include/asm/alternative-asm.h | 4 +- arch/x86/include/asm/alternative.h | 8 ++-- arch/x86/include/asm/clocksource.h | 20 ++++++++++++ arch/x86/include/asm/cpufeature.h | 8 ++-- arch/x86/include/asm/tsc.h | 4 -- arch/x86/include/asm/vgtod.h | 2 +- arch/x86/include/asm/vsyscall.h | 4 -- arch/x86/kernel/Makefile | 7 +---- arch/x86/kernel/alternative.c | 23 ++++++-------- arch/x86/kernel/hpet.c | 9 +----- arch/x86/kernel/tsc.c | 2 +- arch/x86/kernel/vmlinux.lds.S | 3 -- arch/x86/kernel/vread_tsc_64.c | 36 ---------------------- arch/x86/kernel/vsyscall_64.c | 2 +- arch/x86/lib/copy_page_64.S | 9 ++---- arch/x86/lib/memmove_64.S | 11 +++---- arch/x86/vdso/Makefile | 1 + arch/x86/vdso/vclock_gettime.c | 52 ++++++++++++++++++++++++++++---- arch/x86/vdso/vma.c | 32 +++++++++++++++++++ drivers/char/hpet.c | 2 +- include/asm-generic/clocksource.h | 4 ++ include/linux/clocksource.h | 13 ++++---- 26 files changed, 162 insertions(+), 116 deletions(-) create mode 100644 arch/ia64/include/asm/clocksource.h create mode 100644 arch/x86/include/asm/clocksource.h delete mode 100644 arch/x86/kernel/vread_tsc_64.c create mode 100644 include/asm-generic/clocksource.h
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