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Subject[PATCH v2 05/12] task_isolation: arch/x86: enable task isolation functionality
Date
From: Chris Metcalf <cmetcalf@mellanox.com>

In prepare_exit_to_usermode(), run cleanup for tasks exited from
isolation and call task_isolation_start() for tasks with
TIF_TASK_ISOLATION.

In syscall_trace_enter_phase1(), add the necessary support for
reporting syscalls for task-isolation processes.

Add task_isolation_remote() calls for the kernel exception types
that do not result in signals, namely non-signalling page faults.

Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
[abelits@marvell.com: adapted for kernel 5.6]
Signed-off-by: Alex Belits <abelits@marvell.com>
---
arch/x86/Kconfig | 1 +
arch/x86/entry/common.c | 15 +++++++++++++++
arch/x86/include/asm/apic.h | 3 +++
arch/x86/include/asm/thread_info.h | 4 +++-
arch/x86/kernel/apic/ipi.c | 2 ++
arch/x86/mm/fault.c | 4 ++++
6 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index beea77046f9b..9ea6d3e6e77d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -144,6 +144,7 @@ config X86
select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_SECCOMP_FILTER
+ select HAVE_ARCH_TASK_ISOLATION
select HAVE_ARCH_THREAD_STRUCT_WHITELIST
select HAVE_ARCH_STACKLEAK
select HAVE_ARCH_TRACEHOOK
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 9747876980b5..ba8cd75dc7cf 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -26,6 +26,7 @@
#include <linux/livepatch.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
+#include <linux/isolation.h>

#include <asm/desc.h>
#include <asm/traps.h>
@@ -86,6 +87,15 @@ static long syscall_trace_enter(struct pt_regs *regs)
return -1L;
}

+ /*
+ * In task isolation mode, we may prevent the syscall from
+ * running, and if so we also deliver a signal to the process.
+ */
+ if (work & _TIF_TASK_ISOLATION) {
+ if (task_isolation_syscall(regs->orig_ax) == -1)
+ return -1L;
+ work &= ~_TIF_TASK_ISOLATION;
+ }
#ifdef CONFIG_SECCOMP
/*
* Do seccomp after ptrace, to catch any tracer changes.
@@ -189,6 +199,8 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs)
lockdep_assert_irqs_disabled();
lockdep_sys_exit();

+ task_isolation_check_run_cleanup();
+
cached_flags = READ_ONCE(ti->flags);

if (unlikely(cached_flags & EXIT_TO_USERMODE_LOOP_FLAGS))
@@ -204,6 +216,9 @@ __visible inline void prepare_exit_to_usermode(struct pt_regs *regs)
if (unlikely(cached_flags & _TIF_NEED_FPU_LOAD))
switch_fpu_return();

+ if (cached_flags & _TIF_TASK_ISOLATION)
+ task_isolation_start();
+
#ifdef CONFIG_COMPAT
/*
* Compat syscalls set TS_COMPAT. Make sure we clear it before
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 19e94af9cc5d..71149abbb0a0 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -3,6 +3,7 @@
#define _ASM_X86_APIC_H

#include <linux/cpumask.h>
+#include <linux/isolation.h>

#include <asm/alternative.h>
#include <asm/cpufeature.h>
@@ -524,6 +525,7 @@ extern void irq_exit(void);

static inline void entering_irq(void)
{
+ task_isolation_interrupt("irq");
irq_enter();
kvm_set_cpu_l1tf_flush_l1d();
}
@@ -536,6 +538,7 @@ static inline void entering_ack_irq(void)

static inline void ipi_entering_ack_irq(void)
{
+ task_isolation_interrupt("ack irq");
irq_enter();
ack_APIC_irq();
kvm_set_cpu_l1tf_flush_l1d();
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index cf4327986e98..60d107f784ee 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -92,6 +92,7 @@ struct thread_info {
#define TIF_NOCPUID 15 /* CPUID is not accessible in userland */
#define TIF_NOTSC 16 /* TSC is not accessible in userland */
#define TIF_IA32 17 /* IA32 compatibility process */
+#define TIF_TASK_ISOLATION 18 /* task isolation enabled for task */
#define TIF_NOHZ 19 /* in adaptive nohz mode */
#define TIF_MEMDIE 20 /* is terminating due to OOM killer */
#define TIF_POLLING_NRFLAG 21 /* idle is polling for TIF_NEED_RESCHED */
@@ -122,6 +123,7 @@ struct thread_info {
#define _TIF_NOCPUID (1 << TIF_NOCPUID)
#define _TIF_NOTSC (1 << TIF_NOTSC)
#define _TIF_IA32 (1 << TIF_IA32)
+#define _TIF_TASK_ISOLATION (1 << TIF_TASK_ISOLATION)
#define _TIF_NOHZ (1 << TIF_NOHZ)
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
#define _TIF_IO_BITMAP (1 << TIF_IO_BITMAP)
@@ -140,7 +142,7 @@ struct thread_info {
#define _TIF_WORK_SYSCALL_ENTRY \
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
_TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
- _TIF_NOHZ)
+ _TIF_NOHZ | _TIF_TASK_ISOLATION)

/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW_BASE \
diff --git a/arch/x86/kernel/apic/ipi.c b/arch/x86/kernel/apic/ipi.c
index 6ca0f91372fd..b4dfaad6a440 100644
--- a/arch/x86/kernel/apic/ipi.c
+++ b/arch/x86/kernel/apic/ipi.c
@@ -2,6 +2,7 @@

#include <linux/cpumask.h>
#include <linux/smp.h>
+#include <linux/isolation.h>

#include "local.h"

@@ -67,6 +68,7 @@ void native_smp_send_reschedule(int cpu)
WARN(1, "sched: Unexpected reschedule of offline CPU#%d!\n", cpu);
return;
}
+ task_isolation_remote(cpu, "reschedule IPI");
apic->send_IPI(cpu, RESCHEDULE_VECTOR);
}

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index fa4ea09593ab..2175a8655a7d 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -18,6 +18,7 @@
#include <linux/uaccess.h> /* faulthandler_disabled() */
#include <linux/efi.h> /* efi_recover_from_page_fault()*/
#include <linux/mm_types.h>
+#include <linux/isolation.h> /* task_isolation_interrupt */

#include <asm/cpufeature.h> /* boot_cpu_has, ... */
#include <asm/traps.h> /* dotraplinkage, ... */
@@ -1483,6 +1484,9 @@ void do_user_addr_fault(struct pt_regs *regs,
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
}

+ /* No signal was generated, but notify task-isolation tasks. */
+ task_isolation_interrupt("page fault at %#lx", address);
+
check_v8086_mode(regs, address, tsk);
}
NOKPROBE_SYMBOL(do_user_addr_fault);
--
2.20.1
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