[patch V2 11/17] x86/entry: Use generic syscall entry function

From: Thomas Gleixner
Date: Wed Oct 23 2019 - 08:32:28 EST

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From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

Replace the syscall entry work handling with the generic version, Provide
the necessary helper inlines to handle the real architecture specific
parts, e.g. audit and seccomp invocations.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/Kconfig | 1
arch/x86/entry/common.c | 108 +++---------------------------------
arch/x86/include/asm/entry-common.h | 59 +++++++++++++++++++
arch/x86/include/asm/thread_info.h | 5 -
4 files changed, 70 insertions(+), 103 deletions(-)

--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -111,6 +111,7 @@ config X86
select GENERIC_CPU_AUTOPROBE
select GENERIC_CPU_VULNERABILITIES
select GENERIC_EARLY_IOREMAP
+ select GENERIC_ENTRY
select GENERIC_FIND_FIRST_BIT
select GENERIC_IOMAP
select GENERIC_IRQ_EFFECTIVE_AFF_MASK if SMP
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -10,13 +10,13 @@
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
+#include <linux/entry-common.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <linux/tracehook.h>
#include <linux/audit.h>
-#include <linux/seccomp.h>
#include <linux/signal.h>
#include <linux/export.h>
#include <linux/context_tracking.h>
@@ -34,7 +34,6 @@
#include <asm/fpu/api.h>
#include <asm/nospec-branch.h>

-#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>

#ifdef CONFIG_CONTEXT_TRACKING
@@ -48,86 +47,6 @@
static inline void enter_from_user_mode(void) {}
#endif

-static void do_audit_syscall_entry(struct pt_regs *regs, u32 arch)
-{
-#ifdef CONFIG_X86_64
- if (arch == AUDIT_ARCH_X86_64) {
- audit_syscall_entry(regs->orig_ax, regs->di,
- regs->si, regs->dx, regs->r10);
- } else
-#endif
- {
- audit_syscall_entry(regs->orig_ax, regs->bx,
- regs->cx, regs->dx, regs->si);
- }
-}
-
-/*
- * Returns the syscall nr to run (which should match regs->orig_ax) or -1
- * to skip the syscall.
- */
-static long syscall_trace_enter(struct pt_regs *regs)
-{
- u32 arch = in_ia32_syscall() ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64;
-
- struct thread_info *ti = current_thread_info();
- unsigned long ret = 0;
- u32 work;
-
- if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
- BUG_ON(regs != task_pt_regs(current));
-
- work = READ_ONCE(ti->flags);
-
- if (work & (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU)) {
- ret = tracehook_report_syscall_entry(regs);
- if (ret || (work & _TIF_SYSCALL_EMU))
- return -1L;
- }
-
-#ifdef CONFIG_SECCOMP
- /*
- * Do seccomp after ptrace, to catch any tracer changes.
- */
- if (work & _TIF_SECCOMP) {
- struct seccomp_data sd;
-
- sd.arch = arch;
- sd.nr = regs->orig_ax;
- sd.instruction_pointer = regs->ip;
-#ifdef CONFIG_X86_64
- if (arch == AUDIT_ARCH_X86_64) {
- sd.args[0] = regs->di;
- sd.args[1] = regs->si;
- sd.args[2] = regs->dx;
- sd.args[3] = regs->r10;
- sd.args[4] = regs->r8;
- sd.args[5] = regs->r9;
- } else
-#endif
- {
- sd.args[0] = regs->bx;
- sd.args[1] = regs->cx;
- sd.args[2] = regs->dx;
- sd.args[3] = regs->si;
- sd.args[4] = regs->di;
- sd.args[5] = regs->bp;
- }
-
- ret = __secure_computing(&sd);
- if (ret == -1)
- return ret;
- }
-#endif
-
- if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
- trace_sys_enter(regs, regs->orig_ax);
-
- do_audit_syscall_entry(regs, arch);
-
- return ret ?: regs->orig_ax;
-}
-
#define EXIT_TO_USERMODE_LOOP_FLAGS \
(_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
_TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY | _TIF_PATCH_PENDING)
@@ -280,16 +199,13 @@ static void syscall_slow_exit_work(struc
#ifdef CONFIG_X86_64
__visible void do_syscall_64(unsigned long nr, struct pt_regs *regs)
{
- struct thread_info *ti;
-
/* User to kernel transition disabled interrupts. */
trace_hardirqs_off();

enter_from_user_mode();
local_irq_enable();
- ti = current_thread_info();
- if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY)
- nr = syscall_trace_enter(regs);
+
+ nr = syscall_enter_from_usermode(regs, nr);

if (likely(nr < NR_syscalls)) {
nr = array_index_nospec(nr, NR_syscalls);
@@ -316,22 +232,18 @@ static void syscall_slow_exit_work(struc
*/
static __always_inline void do_syscall_32_irqs_on(struct pt_regs *regs)
{
- struct thread_info *ti = current_thread_info();
unsigned int nr = (unsigned int)regs->orig_ax;

#ifdef CONFIG_IA32_EMULATION
- ti->status |= TS_COMPAT;
+ current_thread_info()->status |= TS_COMPAT;
#endif

- if (READ_ONCE(ti->flags) & _TIF_WORK_SYSCALL_ENTRY) {
- /*
- * Subtlety here: if ptrace pokes something larger than
- * 2^32-1 into orig_ax, this truncates it. This may or
- * may not be necessary, but it matches the old asm
- * behavior.
- */
- nr = syscall_trace_enter(regs);
- }
+ /*
+ * Subtlety here: if ptrace pokes something larger than 2^32-1 into
+ * orig_ax, this truncates it. This may or may not be necessary,
+ * but it matches the old asm behavior.
+ */
+ nr = syscall_enter_from_usermode(regs, nr);

if (likely(nr < IA32_NR_syscalls)) {
nr = array_index_nospec(nr, IA32_NR_syscalls);
--- /dev/null
+++ b/arch/x86/include/asm/entry-common.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ASM_X86_ENTRY_COMMON_H
+#define _ASM_X86_ENTRY_COMMON_H
+
+#include <linux/seccomp.h>
+#include <linux/audit.h>
+
+static inline long arch_syscall_enter_seccomp(struct pt_regs *regs)
+{
+#ifdef CONFIG_SECCOMP
+ u32 arch = in_ia32_syscall() ? AUDIT_ARCH_I386 : AUDIT_ARCH_X86_64;
+ struct seccomp_data sd;
+
+ sd.arch = arch;
+ sd.nr = regs->orig_ax;
+ sd.instruction_pointer = regs->ip;
+
+#ifdef CONFIG_X86_64
+ if (arch == AUDIT_ARCH_X86_64) {
+ sd.args[0] = regs->di;
+ sd.args[1] = regs->si;
+ sd.args[2] = regs->dx;
+ sd.args[3] = regs->r10;
+ sd.args[4] = regs->r8;
+ sd.args[5] = regs->r9;
+ } else
+#endif
+ {
+ sd.args[0] = regs->bx;
+ sd.args[1] = regs->cx;
+ sd.args[2] = regs->dx;
+ sd.args[3] = regs->si;
+ sd.args[4] = regs->di;
+ sd.args[5] = regs->bp;
+ }
+
+ return __secure_computing(&sd);
+#else
+ return 0;
+#endif
+}
+#define arch_syscall_enter_seccomp arch_syscall_enter_seccomp
+
+static inline void arch_syscall_enter_audit(struct pt_regs *regs)
+{
+#ifdef CONFIG_X86_64
+ if (in_ia32_syscall()) {
+ audit_syscall_entry(regs->orig_ax, regs->di,
+ regs->si, regs->dx, regs->r10);
+ } else
+#endif
+ {
+ audit_syscall_entry(regs->orig_ax, regs->bx,
+ regs->cx, regs->dx, regs->si);
+ }
+}
+#define arch_syscall_enter_audit arch_syscall_enter_audit
+
+#endif
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -133,11 +133,6 @@ struct thread_info {
#define _TIF_X32 (1 << TIF_X32)
#define _TIF_FSCHECK (1 << TIF_FSCHECK)

-/* Work to do before invoking the actual syscall. */
-#define _TIF_WORK_SYSCALL_ENTRY \
- (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
- _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT)
-
/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW_BASE \
(_TIF_IO_BITMAP|_TIF_NOCPUID|_TIF_NOTSC|_TIF_BLOCKSTEP| \

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