diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-01 08:40:25 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-09-01 08:40:25 -0700 |
| commit | 5778077d03cb25aac9b6a428e18970642fc019e3 (patch) | |
| tree | 2e3f3da1fb99c3646da5ed9a09644696ca5f2309 | |
| parent | 65a99597f044c083983f4274ab049c9ec3b9d764 (diff) | |
| parent | 7e01ebffffedec22cea86ebe94802f909e4579ca (diff) | |
Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm changes from Ingo Molnar:
"The biggest changes in this cycle were:
- Revamp, simplify (and in some cases fix) Time Stamp Counter (TSC)
primitives. (Andy Lutomirski)
- Add new, comprehensible entry and exit handlers written in C.
(Andy Lutomirski)
- vm86 mode cleanups and fixes. (Brian Gerst)
- 32-bit compat code cleanups. (Brian Gerst)
The amount of simplification in low level assembly code is already
palpable:
arch/x86/entry/entry_32.S | 130 +----
arch/x86/entry/entry_64.S | 197 ++-----
but more simplifications are planned.
There's also the usual laudry mix of low level changes - see the
changelog for details"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (83 commits)
x86/asm: Drop repeated macro of X86_EFLAGS_AC definition
x86/asm/msr: Make wrmsrl() a function
x86/asm/delay: Introduce an MWAITX-based delay with a configurable timer
x86/asm: Add MONITORX/MWAITX instruction support
x86/traps: Weaken context tracking entry assertions
x86/asm/tsc: Add rdtscll() merge helper
selftests/x86: Add syscall_nt selftest
selftests/x86: Disable sigreturn_64
x86/vdso: Emit a GNU hash
x86/entry: Remove do_notify_resume(), syscall_trace_leave(), and their TIF masks
x86/entry/32: Migrate to C exit path
x86/entry/32: Remove 32-bit syscall audit optimizations
x86/vm86: Rename vm86->v86flags and v86mask
x86/vm86: Rename vm86->vm86_info to user_vm86
x86/vm86: Clean up vm86.h includes
x86/vm86: Move the vm86 IRQ definitions to vm86.h
x86/vm86: Use the normal pt_regs area for vm86
x86/vm86: Eliminate 'struct kernel_vm86_struct'
x86/vm86: Move fields from 'struct kernel_vm86_struct' to 'struct vm86'
x86/vm86: Move vm86 fields out of 'thread_struct'
...
100 files changed, 2197 insertions, 1384 deletions
diff --git a/arch/um/include/shared/kern_util.h b/arch/um/include/shared/kern_util.h index 83a91f976330..35ab97e4bb9b 100644 --- a/arch/um/include/shared/kern_util.h +++ b/arch/um/include/shared/kern_util.h @@ -22,7 +22,8 @@ extern int kmalloc_ok; extern unsigned long alloc_stack(int order, int atomic); extern void free_stack(unsigned long stack, int order); -extern int do_signal(void); +struct pt_regs; +extern void do_signal(struct pt_regs *regs); extern void interrupt_end(void); extern void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs); diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c index 68b9119841cd..a6d922672b9f 100644 --- a/arch/um/kernel/process.c +++ b/arch/um/kernel/process.c @@ -90,12 +90,14 @@ void *__switch_to(struct task_struct *from, struct task_struct *to) void interrupt_end(void) { + struct pt_regs *regs = ¤t->thread.regs; + if (need_resched()) schedule(); if (test_thread_flag(TIF_SIGPENDING)) - do_signal(); + do_signal(regs); if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME)) - tracehook_notify_resume(¤t->thread.regs); + tracehook_notify_resume(regs); } void exit_thread(void) diff --git a/arch/um/kernel/signal.c b/arch/um/kernel/signal.c index 4f60e4aad790..57acbd67d85d 100644 --- a/arch/um/kernel/signal.c +++ b/arch/um/kernel/signal.c @@ -64,7 +64,7 @@ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) signal_setup_done(err, ksig, singlestep); } -static int kern_do_signal(struct pt_regs *regs) +void do_signal(struct pt_regs *regs) { struct ksignal ksig; int handled_sig = 0; @@ -110,10 +110,4 @@ static int kern_do_signal(struct pt_regs *regs) */ if (!handled_sig) restore_saved_sigmask(); - return handled_sig; -} - -int do_signal(void) -{ - return kern_do_signal(¤t->thread.regs); } diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c index f1b3eb14b855..2077248e8a72 100644 --- a/arch/um/kernel/tlb.c +++ b/arch/um/kernel/tlb.c @@ -291,7 +291,7 @@ void fix_range_common(struct mm_struct *mm, unsigned long start_addr, /* We are under mmap_sem, release it such that current can terminate */ up_write(¤t->mm->mmap_sem); force_sig(SIGKILL, current); - do_signal(); + do_signal(¤t->thread.regs); } } diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c index 557232f758b6..d8a9fce6ee2e 100644 --- a/arch/um/kernel/trap.c +++ b/arch/um/kernel/trap.c @@ -173,7 +173,7 @@ static void bad_segv(struct faultinfo fi, unsigned long ip) void fatal_sigsegv(void) { force_sigsegv(SIGSEGV, current); - do_signal(); + do_signal(¤t->thread.regs); /* * This is to tell gcc that we're not returning - do_signal * can, in general, return, but in this case, it's not, since diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 06dbb5da90c6..48f7433dac6f 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -133,7 +133,7 @@ config X86 select HAVE_PERF_USER_STACK_DUMP select HAVE_REGS_AND_STACK_ACCESS_API select HAVE_SYSCALL_TRACEPOINTS - select HAVE_UID16 if X86_32 + select HAVE_UID16 if X86_32 || IA32_EMULATION select HAVE_UNSTABLE_SCHED_CLOCK select HAVE_USER_RETURN_NOTIFIER select IRQ_FORCED_THREADING @@ -1003,19 +1003,41 @@ config X86_THERMAL_VECTOR def_bool y depends on X86_MCE_INTEL -config VM86 - bool "Enable VM86 support" if EXPERT - default y +config X86_LEGACY_VM86 + bool "Legacy VM86 support (obsolete)" + default n depends on X86_32 ---help--- - This option is required by programs like DOSEMU to run - 16-bit real mode legacy code on x86 processors. It also may - be needed by software like XFree86 to initialize some video - cards via BIOS. Disabling this option saves about 6K. + This option allows user programs to put the CPU into V8086 + mode, which is an 80286-era approximation of 16-bit real mode. + + Some very old versions of X and/or vbetool require this option + for user mode setting. Similarly, DOSEMU will use it if + available to accelerate real mode DOS programs. However, any + recent version of DOSEMU, X, or vbetool should be fully + functional even without kernel VM86 support, as they will all + fall back to (pretty well performing) software emulation. + + Anything that works on a 64-bit kernel is unlikely to need + this option, as 64-bit kernels don't, and can't, support V8086 + mode. This option is also unrelated to 16-bit protected mode + and is not needed to run most 16-bit programs under Wine. + + Enabling this option adds considerable attack surface to the + kernel and slows down system calls and exception handling. + + Unless you use very old userspace or need the last drop of + performance in your real mode DOS games and can't use KVM, + say N here. + +config VM86 + bool + default X86_LEGACY_VM86 config X86_16BIT bool "Enable support for 16-bit segments" if EXPERT default y + depends on MODIFY_LDT_SYSCALL ---help--- This option is required by programs like Wine to run 16-bit protected mode legacy code on x86 processors. Disabling @@ -1510,6 +1532,7 @@ config X86_RESERVE_LOW config MATH_EMULATION bool + depends on MODIFY_LDT_SYSCALL prompt "Math emulation" if X86_32 ---help--- Linux can emulate a math coprocessor (used for floating point @@ -2054,6 +2077,22 @@ config CMDLINE_OVERRIDE This is used to work around broken boot loaders. This should be set to 'N' under normal conditions. +config MODIFY_LDT_SYSCALL + bool "Enable the LDT (local descriptor table)" if EXPERT + default y + ---help--- + Linux can allow user programs to install a per-process x86 + Local Descriptor Table (LDT) using the modify_ldt(2) system + call. This is required to run 16-bit or segmented code such as + DOSEMU or some Wine programs. It is also used by some very old + threading libraries. + + Enabling this feature adds a small amount of overhead to + context switches and increases the low-level kernel attack + surface. Disabling it removes the modify_ldt(2) system call. + + Saying 'N' here may make sense for embedded or server kernels. + source "kernel/livepatch/Kconfig" endmenu @@ -2523,7 +2562,7 @@ config IA32_EMULATION depends on X86_64 select BINFMT_ELF select COMPAT_BINFMT_ELF - select HAVE_UID16 + select ARCH_WANT_OLD_COMPAT_IPC ---help--- Include code to run legacy 32-bit programs under a 64-bit kernel. You should likely turn this on, unless you're @@ -2537,7 +2576,7 @@ config IA32_AOUT config X86_X32 bool "x32 ABI for 64-bit mode" - depends on X86_64 && IA32_EMULATION + depends on X86_64 ---help--- Include code to run binaries for the x32 native 32-bit ABI for 64-bit processors. An x32 process gets access to the @@ -2551,7 +2590,6 @@ config X86_X32 config COMPAT def_bool y depends on IA32_EMULATION || X86_X32 - select ARCH_WANT_OLD_COMPAT_IPC if COMPAT config COMPAT_FOR_U64_ALIGNMENT diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 0f38418719ab..747860c696e1 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -39,6 +39,16 @@ ifdef CONFIG_X86_NEED_RELOCS LDFLAGS_vmlinux := --emit-relocs endif +# +# Prevent GCC from generating any FP code by mistake. +# +# This must happen before we try the -mpreferred-stack-boundary, see: +# +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383 +# +KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow +KBUILD_CFLAGS += $(call cc-option,-mno-avx,) + ifeq ($(CONFIG_X86_32),y) BITS := 32 UTS_MACHINE := i386 @@ -167,9 +177,6 @@ KBUILD_CFLAGS += -pipe KBUILD_CFLAGS += -Wno-sign-compare # KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -# prevent gcc from generating any FP code by mistake -KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -KBUILD_CFLAGS += $(call cc-option,-mno-avx,) KBUILD_CFLAGS += $(mflags-y) KBUILD_AFLAGS += $(mflags-y) diff --git a/arch/x86/boot/compressed/aslr.c b/arch/x86/boot/compressed/aslr.c index d7b1f655b3ef..6a9b96b4624d 100644 --- a/arch/x86/boot/compressed/aslr.c +++ b/arch/x86/boot/compressed/aslr.c @@ -82,7 +82,7 @@ static unsigned long get_random_long(void) if (has_cpuflag(X86_FEATURE_TSC)) { debug_putstr(" RDTSC"); - rdtscll(raw); + raw = rdtsc(); random ^= raw; use_i8254 = false; diff --git a/arch/x86/entry/Makefile b/arch/x86/entry/Makefile index 7a144971db79..bd55dedd7614 100644 --- a/arch/x86/entry/Makefile +++ b/arch/x86/entry/Makefile @@ -2,6 +2,7 @@ # Makefile for the x86 low level entry code # obj-y := entry_$(BITS).o thunk_$(BITS).o syscall_$(BITS).o +obj-y += common.o obj-y += vdso/ obj-y += vsyscall/ diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index f4e6308c4200..3c71dd947c7b 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -135,9 +135,6 @@ For 32-bit we have the following conventions - kernel is built with movq %rbp, 4*8+\offset(%rsp) movq %rbx, 5*8+\offset(%rsp) .endm - .macro SAVE_EXTRA_REGS_RBP offset=0 |