mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-28 11:18:45 +07:00
870568b390
Jürgen Mell reported an FPU state corruption bug under CONFIG_PREEMPT, and bisected it to commit v2.6.19-1363-gacc2076, "i386: add sleazy FPU optimization". Add tsk_used_math() checks to prevent calling math_state_restore() which can sleep in the case of !tsk_used_math(). This prevents making a blocking call in __switch_to(). Apparently "fpu_counter > 5" check is not enough, as in some signal handling and fork/exec scenarios, fpu_counter > 5 and !tsk_used_math() is possible. It's a side effect though. This is the failing scenario: process 'A' in save_i387_ia32() just after clear_used_math() Got an interrupt and pre-empted out. At the next context switch to process 'A' again, kernel tries to restore the math state proactively and sees a fpu_counter > 0 and !tsk_used_math() This results in init_fpu() during the __switch_to()'s math_state_restore() And resulting in fpu corruption which will be saved/restored (save_i387_fxsave and restore_i387_fxsave) during the remaining part of the signal handling after the context switch. Bisected-by: Jürgen Mell <j.mell@t-online.de> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Tested-by: Jürgen Mell <j.mell@t-online.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@kernel.org |
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| acpi | ||
| cpu | ||
| .gitignore | ||
| alternative.c | ||
| aperture_64.c | ||
| apic_32.c | ||
| apic_64.c | ||
| apm_32.c | ||
| asm-offsets_32.c | ||
| asm-offsets_64.c | ||
| asm-offsets.c | ||
| audit_64.c | ||
| bootflag.c | ||
| bugs_64.c | ||
| cpuid.c | ||
| crash_dump_32.c | ||
| crash_dump_64.c | ||
| crash.c | ||
| doublefault_32.c | ||
| ds.c | ||
| e820_32.c | ||
| e820_64.c | ||
| early_printk.c | ||
| early-quirks.c | ||
| efi_32.c | ||
| efi_64.c | ||
| efi_stub_32.S | ||
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| efi.c | ||
| entry_32.S | ||
| entry_64.S | ||
| genapic_64.c | ||
| genapic_flat_64.c | ||
| genx2apic_uv_x.c | ||
| geode_32.c | ||
| head32.c | ||
| head64.c | ||
| head_32.S | ||
| head_64.S | ||
| hpet.c | ||
| i386_ksyms_32.c | ||
| i387.c | ||
| i8237.c | ||
| i8253.c | ||
| i8259_32.c | ||
| i8259_64.c | ||
| init_task.c | ||
| io_apic_32.c | ||
| io_apic_64.c | ||
| io_delay.c | ||
| ioport.c | ||
| ipi.c | ||
| irq_32.c | ||
| irq_64.c | ||
| k8.c | ||
| kdebugfs.c | ||
| kgdb.c | ||
| kprobes.c | ||
| kvm.c | ||
| kvmclock.c | ||
| ldt.c | ||
| machine_kexec_32.c | ||
| machine_kexec_64.c | ||
| Makefile | ||
| mca_32.c | ||
| mfgpt_32.c | ||
| microcode.c | ||
| mmconf-fam10h_64.c | ||
| module_32.c | ||
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| mpparse.c | ||
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| nmi_32.c | ||
| nmi_64.c | ||
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| olpc.c | ||
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| paravirt_patch_64.c | ||
| paravirt.c | ||
| pci-calgary_64.c | ||
| pci-dma.c | ||
| pci-gart_64.c | ||
| pci-nommu.c | ||
| pci-swiotlb_64.c | ||
| pcspeaker.c | ||
| pmtimer_64.c | ||
| process_32.c | ||
| process_64.c | ||
| process.c | ||
| ptrace.c | ||
| quirks.c | ||
| reboot_fixups_32.c | ||
| reboot.c | ||
| relocate_kernel_32.S | ||
| relocate_kernel_64.S | ||
| rtc.c | ||
| scx200_32.c | ||
| setup64.c | ||
| setup_32.c | ||
| setup_64.c | ||
| setup.c | ||
| sigframe.h | ||
| signal_32.c | ||
| signal_64.c | ||
| smp.c | ||
| smpboot.c | ||
| smpcommon_32.c | ||
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| srat_32.c | ||
| stacktrace.c | ||
| step.c | ||
| summit_32.c | ||
| sys_i386_32.c | ||
| sys_x86_64.c | ||
| syscall_64.c | ||
| syscall_table_32.S | ||
| tce_64.c | ||
| test_nx.c | ||
| test_rodata.c | ||
| time_32.c | ||
| time_64.c | ||
| tlb_32.c | ||
| tlb_64.c | ||
| tls.c | ||
| tls.h | ||
| topology.c | ||
| trampoline_32.S | ||
| trampoline_64.S | ||
| trampoline.c | ||
| traps_32.c | ||
| traps_64.c | ||
| tsc_32.c | ||
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| tsc_sync.c | ||
| verify_cpu_64.S | ||
| vm86_32.c | ||
| vmi_32.c | ||
| vmiclock_32.c | ||
| vmlinux_32.lds.S | ||
| vmlinux_64.lds.S | ||
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| vsmp_64.c | ||
| vsyscall_64.c | ||
| x8664_ksyms_64.c | ||