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  1. 06 5月, 2015 1 次提交
  3. 27 4月, 2015 1 次提交
  5. 18 4月, 2015 1 次提交
  7. 17 4月, 2015 5 次提交
  9. 16 4月, 2015 2 次提交
    • O
      x86/ptrace: Fix the TIF_FORCED_TF logic in handle_signal() · fd0f86b6
      由 Oleg Nesterov 提交于 
      When the TIF_SINGLESTEP tracee dequeues a signal,
handle_signal() clears TIF_FORCED_TF and X86_EFLAGS_TF but
leaves TIF_SINGLESTEP set.

If the tracer does PTRACE_SINGLESTEP again, enable_single_step()
sets X86_EFLAGS_TF but not TIF_FORCED_TF.  This means that the
subsequent PTRACE_CONT doesn't not clear X86_EFLAGS_TF, and the
tracee gets the wrong SIGTRAP.

Test-case (needs -O2 to avoid prologue insns in signal handler):

	#include <unistd.h>
	#include <stdio.h>
	#include <sys/ptrace.h>
	#include <sys/wait.h>
	#include <sys/user.h>
	#include <assert.h>
	#include <stddef.h>

	void handler(int n)
	{
		asm("nop");
	}

	int child(void)
	{
		assert(ptrace(PTRACE_TRACEME, 0,0,0) == 0);
		signal(SIGALRM, handler);
		kill(getpid(), SIGALRM);
		return 0x23;
	}

	void *getip(int pid)
	{
		return (void*)ptrace(PTRACE_PEEKUSER, pid,
					offsetof(struct user, regs.rip), 0);
	}

	int main(void)
	{
		int pid, status;

		pid = fork();
		if (!pid)
			return child();

		assert(wait(&status) == pid);
		assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGALRM);

		assert(ptrace(PTRACE_SINGLESTEP, pid, 0, SIGALRM) == 0);
		assert(wait(&status) == pid);
		assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP);
		assert((getip(pid) - (void*)handler) == 0);

		assert(ptrace(PTRACE_SINGLESTEP, pid, 0, SIGALRM) == 0);
		assert(wait(&status) == pid);
		assert(WIFSTOPPED(status) && WSTOPSIG(status) == SIGTRAP);
		assert((getip(pid) - (void*)handler) == 1);

		assert(ptrace(PTRACE_CONT, pid, 0,0) == 0);
		assert(wait(&status) == pid);
		assert(WIFEXITED(status) && WEXITSTATUS(status) == 0x23);

		return 0;
	}

The last assert() fails because PTRACE_CONT wrongly triggers
another single-step and X86_EFLAGS_TF can't be cleared by
debugger until the tracee does sys_rt_sigreturn().

Change handle_signal() to do user_disable_single_step() if
stepping, we do not need to preserve TIF_SINGLESTEP because we
are going to do ptrace_notify(), and it is simply wrong to leak
this bit.

While at it, change the comment to explain why we also need to
clear TF unconditionally after setup_rt_frame().

Note: in the longer term we should probably change
setup_sigcontext() to use get_flags() and then just remove this
user_disable_single_step().  And, the state of TIF_FORCED_TF can
be wrong after restore_sigcontext() which can set/clear TF, this
needs another fix.

This fix fixes the 'single_step_syscall_32' testcase in
the x86 testsuite:

Before:

	~/linux/tools/testing/selftests/x86> ./single_step_syscall_32
	[RUN]   Set TF and check nop
	[OK]    Survived with TF set and 9 traps
	[RUN]   Set TF and check int80
	[OK]    Survived with TF set and 9 traps
	[RUN]   Set TF and check a fast syscall
	[WARN]  Hit 10000 SIGTRAPs with si_addr 0xf7789cc0, ip 0xf7789cc0
	Trace/breakpoint trap (core dumped)

After:

	~/linux/linux/tools/testing/selftests/x86> ./single_step_syscall_32
	[RUN]   Set TF and check nop
	[OK]    Survived with TF set and 9 traps
	[RUN]   Set TF and check int80
	[OK]    Survived with TF set and 9 traps
	[RUN]   Set TF and check a fast syscall
	[OK]    Survived with TF set and 39 traps
	[RUN]   Fast syscall with TF cleared
	[OK]    Nothing unexpected happened
Reported-by: NEvan Teran <eteran@alum.rit.edu>
Reported-by: NPedro Alves <palves@redhat.com>
Tested-by: NAndres Freund <andres@anarazel.de>
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
[ Added x86 self-test info. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>
      fd0f86b6
    • J
      x86: mtrr: if: remove use of seq_printf return value · 3ac62bc0
      由 Joe Perches 提交于 
      The seq_printf return value, because it's frequently misused,
will eventually be converted to void.

See: commit 1f33c41c ("seq_file: Rename seq_overflow() to
     seq_has_overflowed() and make public")
Signed-off-by: NJoe Perches <joe@perches.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      3ac62bc0
  11. 15 4月, 2015 2 次提交
  13. 13 4月, 2015 1 次提交
  15. 12 4月, 2015 1 次提交
  17. 11 4月, 2015 5 次提交
  19. 10 4月, 2015 3 次提交
  21. 09 4月, 2015 8 次提交
  23. 08 4月, 2015 3 次提交
    • D
      x86/asm/entry/64: Add forgotten CFI annotation · 8b3607b5
      由 Denys Vlasenko 提交于 
      Signed-off-by: NDenys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
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: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1428424967-14460-1-git-send-email-dvlasenk@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      8b3607b5
    • D
      x86/asm/entry/irq: Simplify interrupt dispatch table (IDT) layout · 3304c9c3
      由 Denys Vlasenko 提交于 
      Interrupt entry points are handled with the following code,
each 32-byte code block contains seven entry points:

		...
		[push][jump 22] // 4 bytes
		[push][jump 18] // 4 bytes
		[push][jump 14] // 4 bytes
		[push][jump 10] // 4 bytes
		[push][jump  6] // 4 bytes
		[push][jump  2] // 4 bytes
		[push][jump common_interrupt][padding] // 8 bytes

		[push][jump]
		[push][jump]
		[push][jump]
		[push][jump]
		[push][jump]
		[push][jump]
		[push][jump common_interrupt][padding]

		[padding_2]
	common_interrupt:

And there is a table which holds pointers to every entry point,
IOW: to every push.

In cold cache, two jumps are still costlier than one, even
though we get the benefit of them residing in the same
cacheline.

This change replaces short jumps with near ones to
'common_interrupt', and pads every push+jump pair to 8 bytes. This
way, each interrupt takes only one jump.

This change replaces ".p2align CONFIG_X86_L1_CACHE_SHIFT" before
dispatch table with ".align 8" - we do not need anything
stronger than that.

The table of entry addresses (the interrupt[] array) is no
longer necessary, the address of entries can be easily
calculated as (irq_entries_start + i*8).

   text	   data	    bss	    dec	    hex	filename
  12546	      0	      0	  12546	   3102	entry_64.o.before
  11626	      0	      0	  11626	   2d6a	entry_64.o

The size decrease is because 1656 bytes of .init.rodata are
gone. That's initdata, though. The resident size does go up a
bit.

Run-tested (32 and 64 bits).
Acked-and-Tested-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NDenys Vlasenko <dvlasenk@redhat.com>
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/1428090553-7283-1-git-send-email-dvlasenk@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      3304c9c3
    • D
      x86/asm/entry/64: Move opportunistic sysret code to syscall code path · fffbb5dc
      由 Denys Vlasenko 提交于 
      This change does two things:

Copy-pastes "retint_swapgs:" code into syscall handling code,
the copy is under "syscall_return:" label. The code is unchanged
apart from some label renames.

Removes "opportunistic sysret" code from "retint_swapgs:" code
block, since now it won't be reached by syscall return. This in
fact removes most of the code in question.

   text	   data	    bss	    dec	    hex	filename
  12530	      0	      0	  12530	   30f2	entry_64.o.before
  12562	      0	      0	  12562	   3112	entry_64.o

Run-tested.
Acked-and-Tested-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NDenys Vlasenko <dvlasenk@redhat.com>
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/1427993219-7291-1-git-send-email-dvlasenk@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      fffbb5dc
  25. 06 4月, 2015 3 次提交
    • B
      x86/alternatives: Guard NOPs optimization · 69df353f
      由 Borislav Petkov 提交于 
      Take a look at the first instruction byte before optimizing the NOP -
there might be something else there already, like the ALTERNATIVE_2()
in rdtsc_barrier() which NOPs out on AMD even though we just
patched in an MFENCE.

This happens because the alternatives sees X86_FEATURE_MFENCE_RDTSC,
AMD CPUs set it, we patch in the MFENCE and right afterwards it sees
X86_FEATURE_LFENCE_RDTSC which AMD CPUs don't set and we blindly
optimize the NOP.

Checking whether at least the first byte is 0x90 prevents that.
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1428181662-18020-1-git-send-email-bp@alien8.deSigned-off-by: NIngo Molnar <mingo@kernel.org>
      69df353f
    • D
      x86/asm/entry: Clear EXTRA_REGS for all executable formats · fc3e958a
      由 Denys Vlasenko 提交于 
      On failure, sys_execve() does not clobber EXTRA_REGS, so we can
just return to userpsace without saving/restoring them.

On success, ELF_PLAT_INIT() in sys_execve() clears all these
registers.

On other executable formats:

  - binfmt_flat.c has similar FLAT_PLAT_INIT, but x86 (and everyone
    else except sh) doesn't define it.

  - binfmt_elf_fdpic.c has ELF_FDPIC_PLAT_INIT, but x86 (and most
    others) doesn't define it.

  - There are no such hooks in binfmt_aout.c et al. We inherit
    EXTRA_REGS from the prior executable.

This inconsistency was not intended.

This change removes SAVE/RESTORE_EXTRA_REGS in stub_execve,
removes register clearing in ELF_PLAT_INIT(),
and instead simply clears them on success in stub_execve.

Run-tested.
Signed-off-by: NDenys Vlasenko <dvlasenk@redhat.com>
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/1428173719-7637-1-git-send-email-dvlasenk@redhat.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      fc3e958a
    • B
      x86/signal: Remove pax argument from restore_sigcontext · 6a3713f0
      由 Brian Gerst 提交于 
      The 'pax' argument is unnecesary.  Instead, store the RAX value
directly in regs.

This pattern goes all the way back to 2.1.106pre1, when restore_sigcontext()
was changed to return an error code instead of EAX directly:

  https://git.kernel.org/cgit/linux/kernel/git/history/history.git/diff/arch/i386/kernel/signal.c?id=9a8f8b7ca3f319bd668298d447bdf32730e51174

In 2007 sigaltstack syscall support was added, where the return
value of restore_sigcontext() was changed to carry the memory-copying
failure code.

But instead of putting 'ax' into regs->ax directly, it was carried
in via a pointer and then returned, where the generic syscall return
code copied it to regs->ax.

So there was never any deeper reason for this suboptimal pattern, it
was simply never noticed after being introduced.
Signed-off-by: NBrian Gerst <brgerst@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1428152303-17154-1-git-send-email-brgerst@gmail.comSigned-off-by: NIngo Molnar <mingo@kernel.org>
      6a3713f0
  27. 04 4月, 2015 1 次提交
    • B
      x86/alternatives: Fix ALTERNATIVE_2 padding generation properly · dbe4058a
      由 Borislav Petkov 提交于 
      Quentin caught a corner case with the generation of instruction
padding in the ALTERNATIVE_2 macro: if len(orig_insn) <
len(alt1) < len(alt2), then not enough padding gets added and
that is not good(tm) as we could overwrite the beginning of the
next instruction.

Luckily, at the time of this writing, we don't have
ALTERNATIVE_2() invocations which have that problem and even if
we did, a simple fix would be to prepend the instructions with
enough prefixes so that that corner case doesn't happen.

However, best it would be if we fixed it properly. See below for
a simple, abstracted example of what we're doing.

So what we ended up doing is, we compute the

	max(len(alt1), len(alt2)) - len(orig_insn)

and feed that value to the .skip gas directive. The max() cannot
have conditionals due to gas limitations, thus the fancy integer
math.

With this patch, all ALTERNATIVE_2 sites get padded correctly;
generating obscure test cases pass too:

  #define alt_max_short(a, b)    ((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))

  #define gen_skip(orig, alt1, alt2, marker)	\
  	.skip -((alt_max_short(alt1, alt2) - (orig)) > 0) * \
  		(alt_max_short(alt1, alt2) - (orig)),marker

  	.pushsection .text, "ax"
  .globl main
  main:
  	gen_skip(1, 2, 4, 0x09)
  	gen_skip(4, 1, 2, 0x10)
  	...
  	.popsection

Thanks to Quentin for catching it and double-checking the fix!
Reported-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: NBorislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150404133443.GE21152@pd.tnicSigned-off-by: NIngo Molnar <mingo@kernel.org>
      dbe4058a
  29. 03 4月, 2015 3 次提交