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authorThomas Gleixner <tglx@linutronix.de>2020-09-02 02:50:54 +0300
committerThomas Gleixner <tglx@linutronix.de>2020-09-04 16:50:14 +0300
commit4facb95b7adaf77e2da73aafb9ba60996fe42a12 (patch)
treeddb9a047283999071caad1f0ea5b1e5f3e27c703 /kernel
parentd5c678aed5eddb944b8e7ce451b107b39245962d (diff)
downloadlinux-4facb95b7adaf77e2da73aafb9ba60996fe42a12.tar.xz
x86/entry: Unbreak 32bit fast syscall
Andy reported that the syscall treacing for 32bit fast syscall fails: # ./tools/testing/selftests/x86/ptrace_syscall_32 ... [RUN] SYSEMU [FAIL] Initial args are wrong (nr=224, args=10 11 12 13 14 4289172732) ... [RUN] SYSCALL [FAIL] Initial args are wrong (nr=29, args=0 0 0 0 0 4289172732) The eason is that the conversion to generic entry code moved the retrieval of the sixth argument (EBP) after the point where the syscall entry work runs, i.e. ptrace, seccomp, audit... Unbreak it by providing a split up version of syscall_enter_from_user_mode(). - syscall_enter_from_user_mode_prepare() establishes state and enables interrupts - syscall_enter_from_user_mode_work() runs the entry work Replace the call to syscall_enter_from_user_mode() in the 32bit fast syscall C-entry with the split functions and stick the EBP retrieval between them. Fixes: 27d6b4d14f5c ("x86/entry: Use generic syscall entry function") Reported-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/87k0xdjbtt.fsf@nanos.tec.linutronix.de
Diffstat (limited to 'kernel')
-rw-r--r--kernel/entry/common.c35
1 files changed, 29 insertions, 6 deletions
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index fcae019158ca..18683598edbc 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -69,22 +69,45 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall,
return ret ? : syscall_get_nr(current, regs);
}
-noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
+static __always_inline long
+__syscall_enter_from_user_work(struct pt_regs *regs, long syscall)
{
unsigned long ti_work;
- enter_from_user_mode(regs);
- instrumentation_begin();
-
- local_irq_enable();
ti_work = READ_ONCE(current_thread_info()->flags);
if (ti_work & SYSCALL_ENTER_WORK)
syscall = syscall_trace_enter(regs, syscall, ti_work);
- instrumentation_end();
return syscall;
}
+long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall)
+{
+ return __syscall_enter_from_user_work(regs, syscall);
+}
+
+noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall)
+{
+ long ret;
+
+ enter_from_user_mode(regs);
+
+ instrumentation_begin();
+ local_irq_enable();
+ ret = __syscall_enter_from_user_work(regs, syscall);
+ instrumentation_end();
+
+ return ret;
+}
+
+noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs)
+{
+ enter_from_user_mode(regs);
+ instrumentation_begin();
+ local_irq_enable();
+ instrumentation_end();
+}
+
/**
* exit_to_user_mode - Fixup state when exiting to user mode
*