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Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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This vDSO code only gets used by 64-bit kernels, not 32-bit ones.
On 64-bit kernels, the data segment is the same for 32-bit and
64-bit userspace, and the SYSRET instruction loads %ss with its
selector.
So there's no need to repeat it by hand. Segment loads are somewhat
expensive: tens of cycles.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
[ Removed unnecessary comment. ]
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/63da6d778f69fd0f1345d9287f6764d58be519fa.1427482099.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Some assembler versions automagically optimize .eh_frame contents,
changing their size. The CFI in sysenter.S was not using optimal
formatting, so it would be changed by newer/smarter assemblers.
This ran afoul of the wired constant for padding out the other vDSO
images to match its size. This changes the original hand-coded
source to use the optimal format encoding for its operations. That
leaves nothing more for a fancy assembler to do, so the sizes will
match the wired-in expected size regardless of the assembler version.
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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This reorders the code in the 32-bit vDSO images to put the signal
trampolines first and __kernel_vsyscall after them. The order does
not matter to userland, it just uses what AT_SYSINFO or e_entry
says. Since the signal trampolines are the same size in both
versions of the vDSO, putting them first is the simplest way to get
the addresses to line up. This makes it work to use a more compact
layout for the vDSO.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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This puts the syscall version of the 32-bit vDSO in arch/x86/vdso/vdso32/
for 64-bit IA32 support. This is not used yet, but it paves the way for
consolidating the 32-bit vDSO source and build logic all in one place.
Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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