linux/arch/x86/kernel
Oleg Nesterov 66463db4fc x86, fpu: shift drop_init_fpu() from save_xstate_sig() to handle_signal()
save_xstate_sig()->drop_init_fpu() doesn't look right. setup_rt_frame()
can fail after that, in this case the next setup_rt_frame() triggered
by SIGSEGV won't save fpu simply because the old state was lost. This
obviously mean that fpu won't be restored after sys_rt_sigreturn() from
SIGSEGV handler.

Shift drop_init_fpu() into !failed branch in handle_signal().

Test-case (needs -O2):

	#include <stdio.h>
	#include <signal.h>
	#include <unistd.h>
	#include <sys/syscall.h>
	#include <sys/mman.h>
	#include <pthread.h>
	#include <assert.h>

	volatile double D;

	void test(double d)
	{
		int pid = getpid();

		for (D = d; D == d; ) {
			/* sys_tkill(pid, SIGHUP); asm to avoid save/reload
			 * fp regs around "C" call */
			asm ("" : : "a"(200), "D"(pid), "S"(1));
			asm ("syscall" : : : "ax");
		}

		printf("ERR!!\n");
	}

	void sigh(int sig)
	{
	}

	char altstack[4096 * 10] __attribute__((aligned(4096)));

	void *tfunc(void *arg)
	{
		for (;;) {
			mprotect(altstack, sizeof(altstack), PROT_READ);
			mprotect(altstack, sizeof(altstack), PROT_READ|PROT_WRITE);
		}
	}

	int main(void)
	{
		stack_t st = {
			.ss_sp = altstack,
			.ss_size = sizeof(altstack),
			.ss_flags = SS_ONSTACK,
		};

		struct sigaction sa = {
			.sa_handler = sigh,
		};

		pthread_t pt;

		sigaction(SIGSEGV, &sa, NULL);
		sigaltstack(&st, NULL);
		sa.sa_flags = SA_ONSTACK;
		sigaction(SIGHUP, &sa, NULL);

		pthread_create(&pt, NULL, tfunc, NULL);

		test(123.456);
		return 0;
	}

Reported-by: Bean Anderson <bean@azulsystems.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: http://lkml.kernel.org/r/20140902175713.GA21646@redhat.com
Cc: <stable@kernel.org> # v3.7+
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-09-02 14:51:14 -07:00
..
acpi Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-08-13 18:23:32 -06:00
apic x86, irq, PCI: Keep IRQ assignment for runtime power management 2014-08-29 13:38:00 +02:00
cpu PCI changes for the v3.17 merge window (part 2): 2014-08-14 18:10:33 -06:00
kprobes kprobes/x86: Don't try to resolve kprobe faults from userspace 2014-07-16 14:16:32 +02:00
.gitignore
alternative.c kprobes, x86: Allow kprobes on text_poke/hw_breakpoint 2014-04-24 10:03:02 +02:00
amd_gart_64.c x86: enable DMA CMA with swiotlb 2014-06-04 16:53:57 -07:00
amd_nb.c A bunch of EDAC updates all over the place: 2014-04-01 13:54:00 -07:00
apb_timer.c
aperture_64.c x86/gart: Tidy messages and add bridge device info 2014-05-23 10:47:19 -06:00
apm_32.c x86: Remove unused variable "polling" 2014-07-16 12:58:47 +02:00
asm-offsets_32.c
asm-offsets_64.c
asm-offsets.c
audit_64.c
bootflag.c
check.c
cpuid.c x86, cpuid: Fix CPU hotplug callback registration 2014-03-20 13:43:42 +01:00
crash_dump_32.c
crash_dump_64.c
crash.c kexec: create a new config option CONFIG_KEXEC_FILE for new syscall 2014-08-29 16:28:16 -07:00
devicetree.c x86, irq, devicetree: Release IOAPIC pin when PCI device is disabled 2014-06-21 23:05:44 +02:00
doublefault.c
dumpstack_32.c Merge branch 'x86-threadinfo-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-04-01 10:17:18 -07:00
dumpstack_64.c x86: Fix dumpstack_64 irq stack handling 2014-04-02 11:46:50 -07:00
dumpstack.c kprobes, x86: Use NOKPROBE_SYMBOL() instead of __kprobes annotation 2014-04-24 10:26:38 +02:00
e820.c
early_printk.c
early-quirks.c Merge commit '9e9a928eed8796a0a1aaed7e0b676db86ba84594' into drm-next 2014-06-05 20:28:59 +10:00
entry_32.S x86_32, entry: Clean up sysenter_badsys declaration 2014-08-15 13:45:32 -07:00
entry_64.S Merge branches 'x86-build-for-linus', 'x86-cleanups-for-linus' and 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-08-04 16:56:16 -07:00
espfix_64.c x86/espfix/xen: Fix allocation of pages for paravirt page tables 2014-07-14 13:47:32 -07:00
ftrace.c ftrace/x86: Add call to ftrace_graph_is_dead() in function graph code 2014-07-17 09:45:08 -04:00
head32.c asmlinkage, x86: Add explicit __visible to arch/x86/* 2014-05-05 16:07:44 -07:00
head64.c kernel/printk: use symbolic defines for console loglevels 2014-06-04 16:54:17 -07:00
head_32.S x86: fix compile error due to X86_TRAP_NMI use in asm files 2014-03-07 18:58:40 -08:00
head_64.S x86: fix compile error due to X86_TRAP_NMI use in asm files 2014-03-07 18:58:40 -08:00
head.c
hpet.c Merge branch 'x86/vdso' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into next 2014-06-05 08:05:29 -07:00
hw_breakpoint.c kprobes, x86: Allow kprobes on text_poke/hw_breakpoint 2014-04-24 10:03:02 +02:00
i386_ksyms_32.c
i387.c x86/xsaves: Clear reserved bits in xsave header 2014-05-29 14:33:00 -07:00
i8237.c
i8253.c
i8259.c x86, irq, pic: Probe for legacy PIC and set legacy_pic appropriately 2014-04-14 11:49:55 -07:00
io_delay.c
ioport.c
iosf_mbi.c PCI: Remove DEFINE_PCI_DEVICE_TABLE macro use 2014-08-12 12:15:14 -06:00
irq_32.c x86, threadinfo: Redo "x86: Use inline assembler to get sp" 2014-03-10 17:32:01 -07:00
irq_64.c
irq_work.c
irq.c Merge branch 'x86-irq-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-06-12 20:03:47 -07:00
irqinit.c x86: Fix non-PC platform kernel crash on boot due to NULL dereference 2014-08-25 22:36:57 +02:00
jump_label.c
kdebugfs.c
kexec-bzimage64.c kexec: verify the signature of signed PE bzImage 2014-08-08 15:57:33 -07:00
kgdb.c
ksysfs.c
kvm.c Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-06-12 19:18:49 -07:00
kvmclock.c kvm: remove redundant registration of BSP's hv_clock area 2014-02-22 15:53:32 +01:00
ldt.c Revert "x86-64, modify_ldt: Make support for 16-bit segments a runtime option" 2014-05-21 10:22:59 -07:00
machine_kexec_32.c
machine_kexec_64.c kexec: create a new config option CONFIG_KEXEC_FILE for new syscall 2014-08-29 16:28:16 -07:00
Makefile kexec: create a new config option CONFIG_KEXEC_FILE for new syscall 2014-08-29 16:28:16 -07:00
mcount_64.S ftrace: x86: Remove check of obsolete variable function_trace_stop 2014-07-18 13:57:02 -04:00
mmconf-fam10h_64.c
module.c x86, kaslr: fix module lock ordering problem 2014-03-24 10:18:26 -07:00
mpparse.c x86, apic: Remove mps_oem_check callback 2014-07-31 08:05:42 -07:00
msr.c x86, msr: Fix CPU hotplug callback registration 2014-03-20 13:43:42 +01:00
nmi_selftest.c
nmi.c kprobes, x86: Use NOKPROBE_SYMBOL() instead of __kprobes annotation 2014-04-24 10:26:38 +02:00
paravirt_patch_32.c
paravirt_patch_64.c x86_64/entry/xen: Do not invoke espfix64 on Xen 2014-07-28 15:25:40 -07:00
paravirt-spinlocks.c
paravirt.c kprobes, x86: Prohibit probing on native_set_debugreg()/load_idt() 2014-04-24 10:02:58 +02:00
pci-calgary_64.c x86, calgary: Use 8M TCE table size by default 2014-04-10 19:51:32 -07:00
pci-dma.c arch/x86/kernel/pci-dma.c: fix dma_generic_alloc_coherent() when CONFIG_DMA_CMA is enabled 2014-06-04 16:53:57 -07:00
pci-iommu_table.c
pci-nommu.c
pci-swiotlb.c x86: enable DMA CMA with swiotlb 2014-06-04 16:53:57 -07:00
pcspeaker.c
perf_regs.c
pmc_atom.c x86/pmc_atom: Silence shift wrapping warnings in pmc_sleep_tmr_show() 2014-08-02 16:52:17 -07:00
preempt.S
probe_roms.c
process_32.c x86: Keep thread_info on thread stack in x86_32 2014-03-06 16:56:55 -08:00
process_64.c Merge branch 'perf/urgent' into perf/core, to resolve conflict and to prepare for new patches 2014-06-06 07:55:06 +02:00
process.c Define kernel API to get address of each state in xsave area 2014-05-29 14:33:09 -07:00
ptrace.c x86: Keep thread_info on thread stack in x86_32 2014-03-06 16:56:55 -08:00
pvclock.c
quirks.c x86/amd/numa: Fix northbridge quirk to assign correct NUMA node 2014-03-14 11:05:36 +01:00
reboot_fixups_32.c
reboot.c x86/reboot: Add EFI reboot quirk for ACPI Hardware Reduced flag 2014-07-18 21:23:52 +01:00
relocate_kernel_32.S
relocate_kernel_64.S
resource.c x86: don't exclude low BIOS area when allocating address space for non-PCI cards 2014-07-16 12:29:36 -06:00
rtc.c
setup_percpu.c
setup.c arch/x86: Replace plain strings with constants 2014-07-18 21:23:59 +01:00
signal.c x86, fpu: shift drop_init_fpu() from save_xstate_sig() to handle_signal() 2014-09-02 14:51:14 -07:00
smp.c asmlinkage, x86: Add explicit __visible to arch/x86/* 2014-05-05 16:07:44 -07:00
smpboot.c x86, apic: Remove setup_portio_remap callback 2014-07-31 08:05:44 -07:00
stacktrace.c
step.c
sys_x86_64.c
syscall_32.c
syscall_64.c
sysfb_efi.c x86: sysfb: move EFI quirks from efifb to sysfb 2013-08-02 16:17:47 -07:00
sysfb_simplefb.c
sysfb.c
tboot.c
tce_64.c
test_nx.c
test_rodata.c
time.c x86: Fix non-PC platform kernel crash on boot due to NULL dereference 2014-08-25 22:36:57 +02:00
tls.c
tls.h
topology.c
trace_clock.c
tracepoint.c
traps.c x86/kprobes: Fix build errors and blacklist context_track_user 2014-06-14 09:07:44 +02:00
tsc_msr.c
tsc_sync.c
tsc.c Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2014-08-05 17:46:42 -07:00
uprobes.c uprobes/x86: Rename arch_uprobe->def to ->defparam, minor comment updates 2014-06-05 16:21:57 +02:00
verify_cpu.S
vm86_32.c
vmlinux.lds.S x86, vdso: Zero-pad the VVAR page 2014-03-18 12:52:44 -07:00
vsmp_64.c x86/apic/vsmp: Make is_vsmp_box() static 2014-08-01 15:09:45 -07:00
vsyscall_64.c x86_64/vsyscall: Fix warn_bad_vsyscall log output 2014-07-25 16:34:15 -07:00
vsyscall_emu_64.S
vsyscall_gtod.c timekeeping: Create struct tk_read_base and use it in struct timekeeper 2014-07-23 15:01:53 -07:00
vsyscall_trace.h
x86_init.c
x8664_ksyms_64.c
xsave.c x86, fpu: shift drop_init_fpu() from save_xstate_sig() to handle_signal() 2014-09-02 14:51:14 -07:00