UNTRAIN_RET is not needed in native_irq_return_ldt because RET
untraining has already been done at this point.
In addition, when the RETBleed mitigation is IBPB, UNTRAIN_RET clobbers
several registers (AX, CX, DX) so here it trashes user values which are
in these registers.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/35b0d50f-12d1-10c3-f5e8-d6c140486d4a@oracle.com
Commit
ee774dac0d ("x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry()")
moved PUSH_AND_CLEAR_REGS out of error_entry, into its own function, in
part to avoid calling error_entry() for XenPV.
However, commit
7c81c0c921 ("x86/entry: Avoid very early RET")
had to change that because the 'ret' was too early and moved it into
idtentry, bloating the text size, since idtentry is expanded for every
exception vector.
However, with the advent of xen_error_entry() in commit
d147553b64 ("x86/xen: Add UNTRAIN_RET")
it became possible to remove PUSH_AND_CLEAR_REGS from idtentry, back
into *error_entry().
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Do fine-grained Kconfig for all the various retbleed parts.
NOTE: if your compiler doesn't support return thunks this will
silently 'upgrade' your mitigation to IBPB, you might not like this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
If a kernel is built with CONFIG_RETPOLINE=n, but the user still wants
to mitigate Spectre v2 using IBRS or eIBRS, the RSB filling will be
silently disabled.
There's nothing retpoline-specific about RSB buffer filling. Remove the
CONFIG_RETPOLINE guards around it.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Since entry asm is tricky, add a validation pass that ensures the
retbleed mitigation has been done before the first actual RET
instruction.
Entry points are those that either have UNWIND_HINT_ENTRY, which acts
as UNWIND_HINT_EMPTY but marks the instruction as an entry point, or
those that have UWIND_HINT_IRET_REGS at +0.
This is basically a variant of validate_branch() that is
intra-function and it will simply follow all branches from marked
entry points and ensures that all paths lead to ANNOTATE_UNRET_END.
If a path hits RET or an indirection the path is a fail and will be
reported.
There are 3 ANNOTATE_UNRET_END instances:
- UNTRAIN_RET itself
- exception from-kernel; this path doesn't need UNTRAIN_RET
- all early exceptions; these also don't need UNTRAIN_RET
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
jmp2ret mitigates the easy-to-attack case at relatively low overhead.
It mitigates the long speculation windows after a mispredicted RET, but
it does not mitigate the short speculation window from arbitrary
instruction boundaries.
On Zen2, there is a chicken bit which needs setting, which mitigates
"arbitrary instruction boundaries" down to just "basic block boundaries".
But there is no fix for the short speculation window on basic block
boundaries, other than to flush the entire BTB to evict all attacker
predictions.
On the spectrum of "fast & blurry" -> "safe", there is (on top of STIBP
or no-SMT):
1) Nothing System wide open
2) jmp2ret May stop a script kiddy
3) jmp2ret+chickenbit Raises the bar rather further
4) IBPB Only thing which can count as "safe".
Tentative numbers put IBPB-on-entry at a 2.5x hit on Zen2, and a 10x hit
on Zen1 according to lmbench.
[ bp: Fixup feature bit comments, document option, 32-bit build fix. ]
Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Implement Kernel IBRS - currently the only known option to mitigate RSB
underflow speculation issues on Skylake hardware.
Note: since IBRS_ENTER requires fuller context established than
UNTRAIN_RET, it must be placed after it. However, since UNTRAIN_RET
itself implies a RET, it must come after IBRS_ENTER. This means
IBRS_ENTER needs to also move UNTRAIN_RET.
Note 2: KERNEL_IBRS is sub-optimal for XenPV.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Note: needs to be in a section distinct from Retpolines such that the
Retpoline RET substitution cannot possibly use immediate jumps.
ORC unwinding for zen_untrain_ret() and __x86_return_thunk() is a
little tricky but works due to the fact that zen_untrain_ret() doesn't
have any stack ops and as such will emit a single ORC entry at the
start (+0x3f).
Meanwhile, unwinding an IP, including the __x86_return_thunk() one
(+0x40) will search for the largest ORC entry smaller or equal to the
IP, these will find the one ORC entry (+0x3f) and all works.
[ Alexandre: SVM part. ]
[ bp: Build fix, massages. ]
Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Commit
ee774dac0d ("x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry()")
manages to introduce a CALL/RET pair that is before SWITCH_TO_KERNEL_CR3,
which means it is before RETBleed can be mitigated.
Revert to an earlier version of the commit in Fixes. Down side is that
this will bloat .text size somewhat. The alternative is fully reverting
it.
The purpose of this patch was to allow migrating error_entry() to C,
including the whole of kPTI. Much care needs to be taken moving that
forward to not re-introduce this problem of early RETs.
Fixes: ee774dac0d ("x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry()")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Use the return thunk in asm code. If the thunk isn't needed, it will
get patched into a RET instruction during boot by apply_returns().
Since alternatives can't handle relocations outside of the first
instruction, putting a 'jmp __x86_return_thunk' in one is not valid,
therefore carve out the memmove ERMS path into a separate label and jump
to it.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
This is userspace code and doesn't play by the normal kernel rules.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
-----BEGIN PGP SIGNATURE-----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=eG67
-----END PGP SIGNATURE-----
Merge tag 'x86_vdso_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 vdso update from Borislav Petkov:
- Get rid of CONFIG_LEGACY_VSYSCALL_EMULATE as nothing should be using
it anymore
* tag 'x86_vdso_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/vsyscall: Remove CONFIG_LEGACY_VSYSCALL_EMULATE
- Remove function export
- Correct asm constraint
- Fix __setup handlers retval
-----BEGIN PGP SIGNATURE-----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=/WGB
-----END PGP SIGNATURE-----
Merge tag 'x86_misc_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 updates from Borislav Petkov:
"A variety of fixes which don't fit any other tip bucket:
- Remove unnecessary function export
- Correct asm constraint
- Fix __setup handlers retval"
* tag 'x86_misc_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/mm: Cleanup the control_va_addr_alignment() __setup handler
x86: Fix return value of __setup handlers
x86/delay: Fix the wrong asm constraint in delay_loop()
x86/amd_nb: Unexport amd_cache_northbridges()
conventions so that former can be converted to C eventually
- Simplify PUSH_AND_CLEAR_REGS so that it can be used at the system call
entry paths instead of having opencoded, slightly different variants of it
everywhere
- Misc other fixes
-----BEGIN PGP SIGNATURE-----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=P80f
-----END PGP SIGNATURE-----
Merge tag 'x86_asm_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Borislav Petkov:
- A bunch of changes towards streamlining low level asm helpers'
calling conventions so that former can be converted to C eventually
- Simplify PUSH_AND_CLEAR_REGS so that it can be used at the system
call entry paths instead of having opencoded, slightly different
variants of it everywhere
- Misc other fixes
* tag 'x86_asm_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/entry: Fix register corruption in compat syscall
objtool: Fix STACK_FRAME_NON_STANDARD reloc type
linkage: Fix issue with missing symbol size
x86/entry: Remove skip_r11rcx
x86/entry: Use PUSH_AND_CLEAR_REGS for compat
x86/entry: Simplify entry_INT80_compat()
x86/mm: Simplify RESERVE_BRK()
x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS
x86/entry: Don't call error_entry() for XENPV
x86/entry: Move CLD to the start of the idtentry macro
x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry()
x86/entry: Switch the stack after error_entry() returns
x86/traps: Use pt_regs directly in fixup_bad_iret()
Add to confidential guests the necessary memory integrity protection
against malicious hypervisor-based attacks like data replay, memory
remapping and others, thus achieving a stronger isolation from the
hypervisor.
At the core of the functionality is a new structure called a reverse
map table (RMP) with which the guest has a say in which pages get
assigned to it and gets notified when a page which it owns, gets
accessed/modified under the covers so that the guest can take an
appropriate action.
In addition, add support for the whole machinery needed to launch a SNP
guest, details of which is properly explained in each patch.
And last but not least, the series refactors and improves parts of the
previous SEV support so that the new code is accomodated properly and
not just bolted on.
-----BEGIN PGP SIGNATURE-----
iQIzBAABCgAdFiEEzv7L6UO9uDPlPSfHEsHwGGHeVUoFAmKLU2AACgkQEsHwGGHe
VUpb/Q//f4LGiJf4nw1flzpe90uIsHNwAafng3NOjeXmhI/EcOlqPf23WHPCgg3Z
2umfa4sRZyj4aZubDd7tYAoq4qWrQ7pO7viWCNTh0InxBAILOoMPMuq2jSAbq0zV
ASUJXeQ2bqjYxX4JV4N5f3HT2l+k68M0mpGLN0H+O+LV9pFS7dz7Jnsg+gW4ZP25
PMPLf6FNzO/1tU1aoYu80YDP1ne4eReLrNzA7Y/rx+S2NAetNwPn21AALVgoD4Nu
vFdKh4MHgtVbwaQuh0csb/+4vD+tDXAhc8lbIl+Abl9ZxJaDWtAJW5D9e2CnsHk1
NOkHwnrzizzhtGK1g56YPUVRFAWhZYMOI1hR0zGPLQaVqBnN4b+iahPeRiV0XnGE
PSbIHSfJdeiCkvLMCdIAmpE5mRshhRSUfl1CXTCdetMn8xV/qz/vG6bXssf8yhTV
cfLGPHU7gfVmsbR9nk5a8KZ78PaytxOxfIDXvCy8JfQwlIWtieaCcjncrj+sdMJy
0fdOuwvi4jma0cyYuPolKiS1Hn4ldeibvxXT7CZQlIx6jZShMbpfpTTJs11XdtHm
PdDAc1TY3AqI33mpy9DhDQmx/+EhOGxY3HNLT7evRhv4CfdQeK3cPVUWgo4bGNVv
ZnFz7nvmwpyufltW9K8mhEZV267174jXGl6/idxybnlVE7ESr2Y=
=Y8kW
-----END PGP SIGNATURE-----
Merge tag 'x86_sev_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull AMD SEV-SNP support from Borislav Petkov:
"The third AMD confidential computing feature called Secure Nested
Paging.
Add to confidential guests the necessary memory integrity protection
against malicious hypervisor-based attacks like data replay, memory
remapping and others, thus achieving a stronger isolation from the
hypervisor.
At the core of the functionality is a new structure called a reverse
map table (RMP) with which the guest has a say in which pages get
assigned to it and gets notified when a page which it owns, gets
accessed/modified under the covers so that the guest can take an
appropriate action.
In addition, add support for the whole machinery needed to launch a
SNP guest, details of which is properly explained in each patch.
And last but not least, the series refactors and improves parts of the
previous SEV support so that the new code is accomodated properly and
not just bolted on"
* tag 'x86_sev_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits)
x86/entry: Fixup objtool/ibt validation
x86/sev: Mark the code returning to user space as syscall gap
x86/sev: Annotate stack change in the #VC handler
x86/sev: Remove duplicated assignment to variable info
x86/sev: Fix address space sparse warning
x86/sev: Get the AP jump table address from secrets page
x86/sev: Add missing __init annotations to SEV init routines
virt: sevguest: Rename the sevguest dir and files to sev-guest
virt: sevguest: Change driver name to reflect generic SEV support
x86/boot: Put globals that are accessed early into the .data section
x86/boot: Add an efi.h header for the decompressor
virt: sevguest: Fix bool function returning negative value
virt: sevguest: Fix return value check in alloc_shared_pages()
x86/sev-es: Replace open-coded hlt-loop with sev_es_terminate()
virt: sevguest: Add documentation for SEV-SNP CPUID Enforcement
virt: sevguest: Add support to get extended report
virt: sevguest: Add support to derive key
virt: Add SEV-SNP guest driver
x86/sev: Register SEV-SNP guest request platform device
x86/sev: Provide support for SNP guest request NAEs
...
Commit
47f33de4aa ("x86/sev: Mark the code returning to user space as syscall gap")
added a bunch of text references without annotating them, resulting in a
spree of objtool complaints:
vmlinux.o: warning: objtool: vc_switch_off_ist+0x77: relocation to !ENDBR: entry_SYSCALL_64+0x15c
vmlinux.o: warning: objtool: vc_switch_off_ist+0x8f: relocation to !ENDBR: entry_SYSCALL_compat+0xa5
vmlinux.o: warning: objtool: vc_switch_off_ist+0x97: relocation to !ENDBR: .entry.text+0x21ea
vmlinux.o: warning: objtool: vc_switch_off_ist+0xef: relocation to !ENDBR: .entry.text+0x162
vmlinux.o: warning: objtool: __sev_es_ist_enter+0x60: relocation to !ENDBR: entry_SYSCALL_64+0x15c
vmlinux.o: warning: objtool: __sev_es_ist_enter+0x6c: relocation to !ENDBR: .entry.text+0x162
vmlinux.o: warning: objtool: __sev_es_ist_enter+0x8a: relocation to !ENDBR: entry_SYSCALL_compat+0xa5
vmlinux.o: warning: objtool: __sev_es_ist_enter+0xc1: relocation to !ENDBR: .entry.text+0x21ea
Since these text references are used to compare against IP, and are not
an indirect call target, they don't need ENDBR so annotate them away.
Fixes: 47f33de4aa ("x86/sev: Mark the code returning to user space as syscall gap")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220520082604.GQ2578@worktop.programming.kicks-ass.net
When returning to user space, %rsp is user-controlled value.
If it is a SNP-guest and the hypervisor decides to mess with the
code-page for this path while a CPU is executing it, a potential #VC
could hit in the syscall return path and mislead the #VC handler.
So make ip_within_syscall_gap() return true in this case.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20220412124909.10467-1-jiangshanlai@gmail.com
In idtentry_vc(), vc_switch_off_ist() determines a safe stack to
switch to, off of the IST stack. Annotate the new stack switch with
ENCODE_FRAME_POINTER in case UNWINDER_FRAME_POINTER is used.
A stack walk before looks like this:
CPU: 0 PID: 0 Comm: swapper Not tainted 5.18.0-rc7+ #2
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Call Trace:
<TASK>
dump_stack_lvl
dump_stack
kernel_exc_vmm_communication
asm_exc_vmm_communication
? native_read_msr
? __x2apic_disable.part.0
? x2apic_setup
? cpu_init
? trap_init
? start_kernel
? x86_64_start_reservations
? x86_64_start_kernel
? secondary_startup_64_no_verify
</TASK>
and with the fix, the stack dump is exact:
CPU: 0 PID: 0 Comm: swapper Not tainted 5.18.0-rc7+ #3
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Call Trace:
<TASK>
dump_stack_lvl
dump_stack
kernel_exc_vmm_communication
asm_exc_vmm_communication
RIP: 0010:native_read_msr
Code: ...
< snipped regs >
? __x2apic_disable.part.0
x2apic_setup
cpu_init
trap_init
start_kernel
x86_64_start_reservations
x86_64_start_kernel
secondary_startup_64_no_verify
</TASK>
[ bp: Test in a SEV-ES guest and rewrite the commit message to
explain what exactly this does. ]
Fixes: a13644f3a5 ("x86/entry/64: Add entry code for #VC handler")
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220316041612.71357-1-jiangshanlai@gmail.com
CONFIG_LEGACY_VSYSCALL_EMULATE is, as far as I know, only needed for the
combined use of exotic and outdated debugging mechanisms with outdated
binaries. At this point, no one should be using it. Eventually, dynamic
switching of vsyscalls will be implemented, but this is much more
complicated to support in EMULATE mode than XONLY mode.
So let's force all the distros off of EMULATE mode. If anyone actually
needs it, they can set vsyscall=emulate, and the kernel can then get
away with refusing to support newer security models if that option is
set.
[ bp: Remove "we"s. ]
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Florian Weimer <fweimer@redhat.com>
Link: https://lore.kernel.org/r/898932fe61db6a9d61bc2458fa2f6049f1ca9f5c.1652290558.git.luto@kernel.org
Yes, r11 and rcx have been restored previously, but since they're being
popped anyway (into rsi) might as well pop them into their own regs --
setting them to the value they already are.
Less magical code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220506121631.365070674@infradead.org
Since the upper regs don't exist for ia32 code, preserving them
doesn't hurt and it simplifies the code.
This doesn't add any attack surface that would not already be
available through INT80.
Notably:
- 32bit SYSENTER: didn't clear si, dx, cx.
- 32bit SYSCALL, INT80: *do* clear si since the C functions don't
take a second argument.
- 64bit: didn't clear si since the C functions take a second
argument; except the error_entry path might have only one argument,
so clearing si was missing here.
32b SYSENTER should be clearing all those 3 registers, nothing uses them
and selftests pass.
Unconditionally clear rsi since it simplifies code.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220506121631.293889636@infradead.org
Instead of playing silly games with rdi, use rax for simpler and more
consistent code.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220506121631.221072885@infradead.org
__setup() handlers should return 1 to obsolete_checksetup() in
init/main.c to indicate that the boot option has been handled. A return
of 0 causes the boot option/value to be listed as an Unknown kernel
parameter and added to init's (limited) argument (no '=') or environment
(with '=') strings. So return 1 from these x86 __setup handlers.
Examples:
Unknown kernel command line parameters "apicpmtimer
BOOT_IMAGE=/boot/bzImage-517rc8 vdso=1 ring3mwait=disable", will be
passed to user space.
Run /sbin/init as init process
with arguments:
/sbin/init
apicpmtimer
with environment:
HOME=/
TERM=linux
BOOT_IMAGE=/boot/bzImage-517rc8
vdso=1
ring3mwait=disable
Fixes: 2aae950b21 ("x86_64: Add vDSO for x86-64 with gettimeofday/clock_gettime/getcpu")
Fixes: 77b52b4c5c ("x86: add "debugpat" boot option")
Fixes: e16fd002af ("x86/cpufeature: Enable RING3MWAIT for Knights Landing")
Fixes: b8ce335906 ("x86_64: convert to clock events")
Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Link: https://lore.kernel.org/r/20220314012725.26661-1-rdunlap@infradead.org
XENPV doesn't use swapgs_restore_regs_and_return_to_usermode(),
error_entry() and the code between entry_SYSENTER_compat() and
entry_SYSENTER_compat_after_hwframe.
Change the PV-compatible SWAPGS to the ASM instruction swapgs in these
places.
Also remove the definition of SWAPGS since no more users.
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220503032107.680190-7-jiangshanlai@gmail.com
XENPV guests enter already on the task stack and they can't fault for
native_iret() nor native_load_gs_index() since they use their own pvop
for IRET and load_gs_index(). A CR3 switch is not needed either.
So there is no reason to call error_entry() in XENPV.
[ bp: Massage commit message. ]
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220503032107.680190-6-jiangshanlai@gmail.com
The macro idtentry() (through idtentry_body()) calls error_entry()
unconditionally even on XENPV. But XENPV needs to only push and clear
regs.
PUSH_AND_CLEAR_REGS in error_entry() makes the stack not return to its
original place when the function returns, which means it is not possible
to convert it to a C function.
Carve out PUSH_AND_CLEAR_REGS out of error_entry() and into a separate
function and call it before error_entry() in order to avoid calling
error_entry() on XENPV.
It will also allow for error_entry() to be converted to C code that can
use inlined sync_regs() and save a function call.
[ bp: Massage commit message. ]
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20220503032107.680190-4-jiangshanlai@gmail.com
error_entry() calls fixup_bad_iret() before sync_regs() if it is a fault
from a bad IRET, to copy pt_regs to the kernel stack. It switches to the
kernel stack directly after sync_regs().
But error_entry() itself is also a function call, so it has to stash
the address it is going to return to, in %r12 which is unnecessarily
complicated.
Move the stack switching after error_entry() and get rid of the need to
handle the return address.
[ bp: Massage commit message. ]
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220503032107.680190-3-jiangshanlai@gmail.com
Always stash the address error_entry() is going to return to, in %r12
and get rid of the void *error_entry_ret; slot in struct bad_iret_stack
which was supposed to account for it and pt_regs pushed on the stack.
After this, both fixup_bad_iret() and sync_regs() can work on a struct
pt_regs pointer directly.
[ bp: Rewrite commit message, touch ups. ]
Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220503032107.680190-2-jiangshanlai@gmail.com
Objtool can figure out that some \cfunc()s are noreturn and then
complains about certain instances having unreachable tails:
vmlinux.o: warning: objtool: asm_exc_xen_unknown_trap()+0x16: unreachable instruction
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220408094718.441854969@infradead.org
- Add new environment variables, USERCFLAGS and USERLDFLAGS to allow
additional flags to be passed to user-space programs.
- Fix missing fflush() bugs in Kconfig and fixdep
- Fix a minor bug in the comment format of the .config file
- Make kallsyms ignore llvm's local labels, .L*
- Fix UAPI compile-test for cross-compiling with Clang
- Extend the LLVM= syntax to support LLVM=<suffix> form for using a
particular version of LLVm, and LLVM=<prefix> form for using custom
LLVM in a particular directory path.
- Clean up Makefiles
-----BEGIN PGP SIGNATURE-----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=84rW
-----END PGP SIGNATURE-----
Merge tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:
- Add new environment variables, USERCFLAGS and USERLDFLAGS to allow
additional flags to be passed to user-space programs.
- Fix missing fflush() bugs in Kconfig and fixdep
- Fix a minor bug in the comment format of the .config file
- Make kallsyms ignore llvm's local labels, .L*
- Fix UAPI compile-test for cross-compiling with Clang
- Extend the LLVM= syntax to support LLVM=<suffix> form for using a
particular version of LLVm, and LLVM=<prefix> form for using custom
LLVM in a particular directory path.
- Clean up Makefiles
* tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: Make $(LLVM) more flexible
kbuild: add --target to correctly cross-compile UAPI headers with Clang
fixdep: use fflush() and ferror() to ensure successful write to files
arch: syscalls: simplify uapi/kapi directory creation
usr/include: replace extra-y with always-y
certs: simplify empty certs creation in certs/Makefile
certs: include certs/signing_key.x509 unconditionally
kallsyms: ignore all local labels prefixed by '.L'
kconfig: fix missing '# end of' for empty menu
kconfig: add fflush() before ferror() check
kbuild: replace $(if A,A,B) with $(or A,B)
kbuild: Add environment variables for userprogs flags
kbuild: unify cmd_copy and cmd_shipped
$(shell ...) expands to empty. There is no need to assign it to _dummy.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Commit 0bf6276392 ("x32: Warn and disable rather than error if
binutils too old") added a small test in arch/x86/Makefile because
binutils 2.22 or newer is needed to properly support elf32-x86-64. This
check is no longer necessary, as the minimum supported version of
binutils is 2.23, which is enforced at configuration time with
scripts/min-tool-version.sh.
Remove this check and replace all uses of CONFIG_X86_X32 with
CONFIG_X86_X32_ABI, as two symbols are no longer necessary.
[nathan: Rebase, fix up a few places where CONFIG_X86_X32 was still
used, and simplify commit message to satisfy -tip requirements]
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220314194842.3452-2-nathan@kernel.org
Annotate away some of the generic code references. This is things
where we take the address of a symbol for exception handling or return
addresses (eg. context switch).
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.877758523@infradead.org
Kernel entry points should be having ENDBR on for IBT configs.
The SYSCALL entry points are found through taking their respective
address in order to program them in the MSRs, while the exception
entry points are found through UNWIND_HINT_IRET_REGS.
The rule is that any UNWIND_HINT_IRET_REGS at sym+0 should have an
ENDBR, see the later objtool ibt validation patch.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.933157479@infradead.org
Even though Xen currently doesn't advertise IBT, prepare for when it
will eventually do so and sprinkle the ENDBR dust accordingly.
Even though most of the entry points are IRET like, the CPL0
Hypervisor can set WAIT-FOR-ENDBR and demand ENDBR at these sites.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.873919996@infradead.org
By doing an early rewrite of 'jmp native_iret` in
restore_regs_and_return_to_kernel() we can get rid of the last
INTERRUPT_RETURN user and paravirt_iret.
Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.815039833@infradead.org
Since commit 5c8f6a2e31 ("x86/xen: Add
xenpv_restore_regs_and_return_to_usermode()") Xen will no longer reach
this code and we can do away with the paravirt
SWAPGS/INTERRUPT_RETURN.
Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154317.756014488@infradead.org
Pull signal/exit/ptrace updates from Eric Biederman:
"This set of changes deletes some dead code, makes a lot of cleanups
which hopefully make the code easier to follow, and fixes bugs found
along the way.
The end-game which I have not yet reached yet is for fatal signals
that generate coredumps to be short-circuit deliverable from
complete_signal, for force_siginfo_to_task not to require changing
userspace configured signal delivery state, and for the ptrace stops
to always happen in locations where we can guarantee on all
architectures that the all of the registers are saved and available on
the stack.
Removal of profile_task_ext, profile_munmap, and profile_handoff_task
are the big successes for dead code removal this round.
A bunch of small bug fixes are included, as most of the issues
reported were small enough that they would not affect bisection so I
simply added the fixes and did not fold the fixes into the changes
they were fixing.
There was a bug that broke coredumps piped to systemd-coredump. I
dropped the change that caused that bug and replaced it entirely with
something much more restrained. Unfortunately that required some
rebasing.
Some successes after this set of changes: There are few enough calls
to do_exit to audit in a reasonable amount of time. The lifetime of
struct kthread now matches the lifetime of struct task, and the
pointer to struct kthread is no longer stored in set_child_tid. The
flag SIGNAL_GROUP_COREDUMP is removed. The field group_exit_task is
removed. Issues where task->exit_code was examined with
signal->group_exit_code should been examined were fixed.
There are several loosely related changes included because I am
cleaning up and if I don't include them they will probably get lost.
The original postings of these changes can be found at:
https://lkml.kernel.org/r/87a6ha4zsd.fsf@email.froward.int.ebiederm.orghttps://lkml.kernel.org/r/87bl1kunjj.fsf@email.froward.int.ebiederm.orghttps://lkml.kernel.org/r/87r19opkx1.fsf_-_@email.froward.int.ebiederm.org
I trimmed back the last set of changes to only the obviously correct
once. Simply because there was less time for review than I had hoped"
* 'signal-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (44 commits)
ptrace/m68k: Stop open coding ptrace_report_syscall
ptrace: Remove unused regs argument from ptrace_report_syscall
ptrace: Remove second setting of PT_SEIZED in ptrace_attach
taskstats: Cleanup the use of task->exit_code
exit: Use the correct exit_code in /proc/<pid>/stat
exit: Fix the exit_code for wait_task_zombie
exit: Coredumps reach do_group_exit
exit: Remove profile_handoff_task
exit: Remove profile_task_exit & profile_munmap
signal: clean up kernel-doc comments
signal: Remove the helper signal_group_exit
signal: Rename group_exit_task group_exec_task
coredump: Stop setting signal->group_exit_task
signal: Remove SIGNAL_GROUP_COREDUMP
signal: During coredumps set SIGNAL_GROUP_EXIT in zap_process
signal: Make coredump handling explicit in complete_signal
signal: Have prepare_signal detect coredumps using signal->core_state
signal: Have the oom killer detect coredumps using signal->core_state
exit: Move force_uaccess back into do_exit
exit: Guarantee make_task_dead leaks the tsk when calling do_task_exit
...
Merge misc updates from Andrew Morton:
"146 patches.
Subsystems affected by this patch series: kthread, ia64, scripts,
ntfs, squashfs, ocfs2, vfs, and mm (slab-generic, slab, kmemleak,
dax, kasan, debug, pagecache, gup, shmem, frontswap, memremap,
memcg, selftests, pagemap, dma, vmalloc, memory-failure, hugetlb,
userfaultfd, vmscan, mempolicy, oom-kill, hugetlbfs, migration, thp,
ksm, page-poison, percpu, rmap, zswap, zram, cleanups, hmm, and
damon)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (146 commits)
mm/damon: hide kernel pointer from tracepoint event
mm/damon/vaddr: hide kernel pointer from damon_va_three_regions() failure log
mm/damon/vaddr: use pr_debug() for damon_va_three_regions() failure logging
mm/damon/dbgfs: remove an unnecessary variable
mm/damon: move the implementation of damon_insert_region to damon.h
mm/damon: add access checking for hugetlb pages
Docs/admin-guide/mm/damon/usage: update for schemes statistics
mm/damon/dbgfs: support all DAMOS stats
Docs/admin-guide/mm/damon/reclaim: document statistics parameters
mm/damon/reclaim: provide reclamation statistics
mm/damon/schemes: account how many times quota limit has exceeded
mm/damon/schemes: account scheme actions that successfully applied
mm/damon: remove a mistakenly added comment for a future feature
Docs/admin-guide/mm/damon/usage: update for kdamond_pid and (mk|rm)_contexts
Docs/admin-guide/mm/damon/usage: mention tracepoint at the beginning
Docs/admin-guide/mm/damon/usage: remove redundant information
Docs/admin-guide/mm/damon/usage: update for scheme quotas and watermarks
mm/damon: convert macro functions to static inline functions
mm/damon: modify damon_rand() macro to static inline function
mm/damon: move damon_rand() definition into damon.h
...
misleading/wrong stacktraces and confuse RELIABLE_STACKTRACE and
LIVEPATCH as the backtrace misses the function which is being fixed up.
- Add Straight Light Speculation mitigation support which uses a new
compiler switch -mharden-sls= which sticks an INT3 after a RET or an
indirect branch in order to block speculation after them. Reportedly,
CPUs do speculate behind such insns.
- The usual set of cleanups and improvements
-----BEGIN PGP SIGNATURE-----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=R52z
-----END PGP SIGNATURE-----
Merge tag 'x86_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 core updates from Borislav Petkov:
- Get rid of all the .fixup sections because this generates
misleading/wrong stacktraces and confuse RELIABLE_STACKTRACE and
LIVEPATCH as the backtrace misses the function which is being fixed
up.
- Add Straight Line Speculation mitigation support which uses a new
compiler switch -mharden-sls= which sticks an INT3 after a RET or an
indirect branch in order to block speculation after them. Reportedly,
CPUs do speculate behind such insns.
- The usual set of cleanups and improvements
* tag 'x86_core_for_v5.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
x86/entry_32: Fix segment exceptions
objtool: Remove .fixup handling
x86: Remove .fixup section
x86/word-at-a-time: Remove .fixup usage
x86/usercopy: Remove .fixup usage
x86/usercopy_32: Simplify __copy_user_intel_nocache()
x86/sgx: Remove .fixup usage
x86/checksum_32: Remove .fixup usage
x86/vmx: Remove .fixup usage
x86/kvm: Remove .fixup usage
x86/segment: Remove .fixup usage
x86/fpu: Remove .fixup usage
x86/xen: Remove .fixup usage
x86/uaccess: Remove .fixup usage
x86/futex: Remove .fixup usage
x86/msr: Remove .fixup usage
x86/extable: Extend extable functionality
x86/entry_32: Remove .fixup usage
x86/entry_64: Remove .fixup usage
x86/copy_mc_64: Remove .fixup usage
...
The LKP robot reported that commit in Fixes: caused a failure. Turns out
the ldt_gdt_32 selftest turns into an infinite loop trying to clear the
segment.
As discovered by Sean, what happens is that PARANOID_EXIT_TO_KERNEL_MODE
in the handle_exception_return path overwrites the entry stack data with
the task stack data, restoring the "bad" segment value.
Instead of having the exception retry the instruction, have it emulate
the full instruction. Replace EX_TYPE_POP_ZERO with EX_TYPE_POP_REG
which will do the equivalent of: POP %reg; MOV $imm, %reg.
In order to encode the segment registers, add them as registers 8-11 for
32-bit.
By setting regs->[defg]s the (nested) RESTORE_REGS will pop this value
at the end of the exception handler and by increasing regs->sp, it will
have skipped the stack slot.
This was debugged by Sean Christopherson <seanjc@google.com>.
[ bp: Add EX_REG_GS too. ]
Fixes: aa93e2ad74 ("x86/entry_32: Remove .fixup usage")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/Yd1l0gInc4zRcnt/@hirez.programming.kicks-ass.net
The -nostdlib option requests the compiler to not use the standard
system startup files or libraries when linking. It is effective only
when $(CC) is used as a linker driver.
Since
379d98ddf4 ("x86: vdso: Use $LD instead of $CC to link")
$(LD) is directly used, hence -nostdlib is unneeded.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20211107162641.324688-1-masahiroy@kernel.org
