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3fb0fdb3bb
linux/arch/x86/kernel
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Andy Lutomirski 3fb0fdb3bb x86/stackprotector/32: Make the canary into a regular percpu variable 
On 32-bit kernels, the stackprotector canary is quite nasty -- it is
stored at %gs:(20), which is nasty because 32-bit kernels use %fs for
percpu storage.  It's even nastier because it means that whether %gs
contains userspace state or kernel state while running kernel code
depends on whether stackprotector is enabled (this is
CONFIG_X86_32_LAZY_GS), and this setting radically changes the way
that segment selectors work.  Supporting both variants is a
maintenance and testing mess.

Merely rearranging so that percpu and the stack canary
share the same segment would be messy as the 32-bit percpu address
layout isn't currently compatible with putting a variable at a fixed
offset.

Fortunately, GCC 8.1 added options that allow the stack canary to be
accessed as %fs:__stack_chk_guard, effectively turning it into an ordinary
percpu variable.  This lets us get rid of all of the code to manage the
stack canary GDT descriptor and the CONFIG_X86_32_LAZY_GS mess.

(That name is special.  We could use any symbol we want for the
 %fs-relative mode, but for CONFIG_SMP=n, gcc refuses to let us use any
 name other than __stack_chk_guard.)

Forcibly disable stackprotector on older compilers that don't support
the new options and turn the stack canary into a percpu variable. The
"lazy GS" approach is now used for all 32-bit configurations.

Also makes load_gs_index() work on 32-bit kernels. On 64-bit kernels,
it loads the GS selector and updates the user GSBASE accordingly. (This
is unchanged.) On 32-bit kernels, it loads the GS selector and updates
GSBASE, which is now always the user base. This means that the overall
effect is the same on 32-bit and 64-bit, which avoids some ifdeffery.

 [ bp: Massage commit message. ]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/c0ff7dba14041c7e5d1cae5d4df052f03759bef3.1613243844.git.luto@kernel.org
2021-03-08 13:19:05 +01:00
..
acpi x86/acpi: Support objtool validation in wakeup_64.S 2021-01-26 11:33:03 -06:00
apic Rework of the X86 irq stack handling: 2021-02-24 16:32:23 -08:00
cpu x86/stackprotector/32: Make the canary into a regular percpu variable 2021-03-08 13:19:05 +01:00
fpu x86/fpu/xstate: Use sizeof() instead of a constant 2021-01-29 12:33:17 +01:00
kprobes x86/kprobes: Do not decode opcode in resume_execution() 2021-01-05 15:42:30 +01:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
alternative.c - Remove all uses of TIF_IA32 and TIF_X32 and reclaim the two bits in the end 2020-12-14 13:45:26 -08:00
amd_gart_64.c dma-mapping: split <linux/dma-mapping.h> 2020-10-06 07:07:03 +02:00
amd_nb.c x86/CPU/AMD: Remove amd_get_nb_id() 2020-11-19 11:43:17 +01:00
aperture_64.c
apm_32.c
asm-offsets_32.c x86/stackprotector/32: Make the canary into a regular percpu variable 2021-03-08 13:19:05 +01:00
asm-offsets_64.c x86/xen: Drop USERGS_SYSRET64 paravirt call 2021-02-10 12:32:07 +01:00
asm-offsets.c x86/head/64: Remove unused GET_CR2_INTO() macro 2020-11-18 18:09:38 +01:00
audit_64.c x86/audit: Fix a -Wmissing-prototypes warning for ia32_classify_syscall() 2020-05-19 18:03:07 +02:00
bootflag.c
check.c
cpuid.c smp: Cleanup smp_call_function*() 2020-11-24 16:47:49 +01:00
crash_core_32.c mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
crash_core_64.c mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
crash_dump_32.c x86/crashdump/32: Simplify copy_oldmem_page() 2020-11-24 14:42:09 +01:00
crash_dump_64.c
crash.c x86/crash: Correct the address boundary of function parameters 2020-08-07 01:32:00 +02:00
devicetree.c x86/devicetree: Fix the ioapic interrupt type table 2020-10-28 20:26:24 +01:00
doublefault_32.c x86/stackprotector/32: Make the canary into a regular percpu variable 2021-03-08 13:19:05 +01:00
dumpstack_32.c x86/32: Remove CONFIG_DOUBLEFAULT 2020-04-14 14:24:05 +02:00
dumpstack_64.c x86/irq/64: Adjust the per CPU irq stack pointer by 8 2021-02-10 23:34:14 +01:00
dumpstack.c - Remove all uses of TIF_IA32 and TIF_X32 and reclaim the two bits in the end 2020-12-14 13:45:26 -08:00
e820.c efi/fake_mem: arrange for a resource entry per efi_fake_mem instance 2020-10-13 18:38:27 -07:00
early_printk.c mm: reorder includes after introduction of linux/pgtable.h 2020-06-09 09:39:13 -07:00
early-quirks.c x86/gpu: add RKL stolen memory support 2020-05-20 08:35:22 -07:00
ebda.c
eisa.c
espfix_64.c mm: introduce include/linux/pgtable.h 2020-06-09 09:39:13 -07:00
ftrace_32.S x86: Change {JMP,CALL}_NOSPEC argument 2020-04-30 20:14:34 +02:00
ftrace_64.S x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S 2021-01-26 11:33:02 -06:00
ftrace.c x86/ftrace: Do not jump to direct code in created trampolines 2020-06-29 11:42:48 -04:00
head32.c
head64.c x86/head64: Remove duplicate include 2020-11-20 17:43:15 +01:00
head_32.S x86/stackprotector/32: Make the canary into a regular percpu variable 2021-03-08 13:19:05 +01:00
head_64.S - Fix the vmlinux size check on 64-bit along with adding useful clarifications on the topic 2020-12-14 13:54:50 -08:00
hpet.c x86/hpet: Use irq_find_matching_fwspec() to find remapping irqdomain 2020-10-28 20:26:28 +01:00
hw_breakpoint.c x86/debug: Prevent data breakpoints on cpu_dr7 2021-02-05 20:13:12 +01:00
i8237.c
i8253.c
i8259.c x86/i8259: Use printk_deferred() to prevent deadlock 2020-07-29 16:27:16 +02:00
idt.c This feature enhances the current guest memory encryption support 2020-10-14 10:21:34 -07:00
io_delay.c
ioport.c x86/ioperm: Prevent a memory leak when fork fails 2020-05-28 21:36:20 +02:00
irq_32.c softirq: Move do_softirq_own_stack() to generic asm header 2021-02-10 23:34:16 +01:00
irq_64.c x86/softirq/64: Inline do_softirq_own_stack() 2021-02-10 23:34:17 +01:00
irq_work.c x86/entry: Convert various system vectors 2020-06-11 15:15:14 +02:00
irq.c Rework of the X86 irq stack handling: 2021-02-24 16:32:23 -08:00
irqflags.S x86/pv: Rework arch_local_irq_restore() to not use popf 2021-02-10 12:36:45 +01:00
irqinit.c x86/headers: Remove APIC headers from <asm/smp.h> 2020-08-06 16:13:09 +02:00
itmt.c sysctl: pass kernel pointers to ->proc_handler 2020-04-27 02:07:40 -04:00
jailhouse.c locking/seqlock, headers: Untangle the spaghetti monster 2020-08-06 16:13:13 +02:00
jump_label.c x86/jump_label: Move 'inline' keyword placement 2020-03-27 11:05:41 +01:00
kdebugfs.c
kexec-bzimage64.c x86/kexec: Use up-to-dated screen_info copy to fill boot params 2020-10-14 17:05:03 +02:00
kgdb.c x86/debug: Change thread.debugreg6 to thread.virtual_dr6 2020-09-04 15:12:58 +02:00
ksysfs.c
kvm.c x86/kvm: Enable 15-bit extension when KVM_FEATURE_MSI_EXT_DEST_ID detected 2020-10-28 20:26:33 +01:00
kvmclock.c x86/kvm: remove unused macro HV_CLOCK_SIZE 2020-11-16 13:14:21 -05:00
ldt.c x86/ldt: Use tlb_gather_mmu_fullmm() when freeing LDT page-tables 2021-01-29 20:02:29 +01:00
machine_kexec_32.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
machine_kexec_64.c mm: don't include asm/pgtable.h if linux/mm.h is already included 2020-06-09 09:39:13 -07:00
Makefile x86/apb_timer: Remove driver for deprecated platform 2021-02-09 15:28:37 +01:00
mmconf-fam10h_64.c
module.c x86/build: Treat R_386_PLT32 relocation as R_386_PC32 2021-01-28 12:24:06 +01:00
mpparse.c Surgery of the MSI interrupt handling to prepare the support of upcoming 2020-10-12 11:40:41 -07:00
msr.c x86/MSR: Filter MSR writes through X86_IOC_WRMSR_REGS ioctl too 2021-01-27 19:06:47 +01:00
nmi_selftest.c
nmi.c x86/entry: Move nmi entry/exit into common code 2020-11-04 22:55:36 +01:00
paravirt_patch.c x86/pv: Rework arch_local_irq_restore() to not use popf 2021-02-10 12:36:45 +01:00
paravirt-spinlocks.c
paravirt.c x86/pv: Rework arch_local_irq_restore() to not use popf 2021-02-10 12:36:45 +01:00
pci-dma.c dma-mapping: move dma-debug.h to kernel/dma/ 2020-10-06 07:07:05 +02:00
pci-iommu_table.c x86: Remove definition of DEBUG 2021-01-15 08:23:10 +01:00
pci-swiotlb.c
pcspeaker.c
perf_regs.c - Remove all uses of TIF_IA32 and TIF_X32 and reclaim the two bits in the end 2020-12-14 13:45:26 -08:00
platform-quirks.c
pmem.c
probe_roms.c maccess: make get_kernel_nofault() check for minimal type compatibility 2020-06-18 12:10:37 -07:00
process_32.c x86/dumpstack: Add log_lvl to __show_regs() 2020-07-22 23:56:53 +02:00
process_64.c x86/irq: Sanitize irq stack tracking 2021-02-10 23:34:13 +01:00
process.c arch: setup PF_IO_WORKER threads like PF_KTHREAD 2021-02-21 17:25:22 -07:00
process.h
ptrace.c x86/ptrace: Clean up PTRACE_GETREGS/PTRACE_PUTREGS regset selection 2021-02-04 12:33:15 +01:00
pvclock.c x86/vdso: Use generic VDSO clock mode storage 2020-02-17 14:40:23 +01:00
quirks.c x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}() 2020-10-06 11:18:04 +02:00
reboot_fixups_32.c
reboot.c x86: 2021-02-21 13:31:43 -08:00
relocate_kernel_32.S
relocate_kernel_64.S x86/kexec: Make relocate_kernel_64.S objtool clean 2020-03-25 18:28:28 +01:00
resource.c
rtc.c
setup_percpu.c x86/stackprotector/32: Make the canary into a regular percpu variable 2021-03-08 13:19:05 +01:00
setup.c sfi: Remove framework for deprecated firmware 2021-02-15 20:09:46 +01:00
sev_verify_cbit.S x86/boot/compressed/64: Check SEV encryption in 64-bit boot-path 2020-10-29 18:06:52 +01:00
sev-es-shared.c x86/sev-es: Fix SEV-ES OUT/IN immediate opcode vc handling 2021-01-05 18:55:00 +01:00
sev-es.c x86/sev: Fix nonistr violation 2021-01-12 21:10:58 +01:00
signal_compat.c A set of updates for entry/exit handling: 2020-12-14 17:13:53 -08:00
signal.c Merge branch 'core/urgent' into core/entry 2020-11-04 18:14:52 +01:00
smp.c x86/entry: Convert reschedule interrupt to IDTENTRY_SYSVEC_SIMPLE 2020-06-11 15:15:16 +02:00
smpboot.c cpufreq: ACPI: Update arch scale-invariance max perf ratio if CPPC is not there 2021-02-08 13:45:51 +01:00
stacktrace.c stacktrace: Remove reliable argument from arch_stack_walk() callback 2020-09-18 14:24:16 +01:00
static_call.c static_call/x86: Add __static_call_return0() 2021-02-17 14:08:43 +01:00
step.c entry: Ensure trap after single-step on system call return 2021-02-06 00:21:42 +01:00
sys_ia32.c x86: switch to kernel_clone() 2020-08-20 13:12:58 +02:00
sys_x86_64.c x86/mm: Refine mmap syscall implementation 2021-01-05 19:07:42 +01:00
sysfb_efi.c
sysfb_simplefb.c
sysfb.c
tboot.c mm/gup: prevent gup_fast from racing with COW during fork 2020-12-15 12:13:39 -08:00
time.c A set of fixes and updates for x86: 2020-06-11 15:54:31 -07:00
tls.c x86/stackprotector/32: Make the canary into a regular percpu variable 2021-03-08 13:19:05 +01:00
tls.h x86: switch to ->regset_get() 2020-07-27 14:31:07 -04:00
topology.c genirq: Move irq_has_action() into core code 2020-12-15 16:19:30 +01:00
trace_clock.c
tracepoint.c x86/entry: Convert reschedule interrupt to IDTENTRY_SYSVEC_SIMPLE 2020-06-11 15:15:16 +02:00
traps.c x86/split-lock: Avoid returning with interrupts enabled 2020-12-22 13:06:10 -08:00
tsc_msr.c Misc fixes and small updates all around the place: 2020-08-15 10:38:03 -07:00
tsc_sync.c x86: Fix a handful of typos 2020-02-16 20:58:06 +01:00
tsc.c x86/tsc: Use seqcount_latch_t 2020-09-10 11:19:29 +02:00
umip.c x86/umip: Factor out instruction decoding 2020-09-07 19:45:24 +02:00
unwind_frame.c fork-v5.9 2020-08-04 14:47:45 -07:00
unwind_guess.c
unwind_orc.c x86/unwind/orc: Change REG_SP_INDIRECT 2021-02-10 20:53:51 +01:00
uprobes.c Perf updates: 2020-12-14 17:34:12 -08:00
verify_cpu.S
vm86_32.c x86/vm86/32: Remove VM86_SCREEN_BITMAP support 2021-01-21 20:08:53 +01:00
vmlinux.lds.S x86/build: Fix vmlinux size check on 64-bit 2020-10-29 21:54:35 +01:00
vsmp_64.c
x86_init.c x86/apic: Support 15 bits of APIC ID in MSI where available 2020-10-28 20:26:29 +01:00