[tip:core/core] x86/traps: Weaken context tracking entry assertions
Commit-ID: f0a97af83f6287357dcc100c859ec0066f164f32
Gitweb: http://git.kernel.org/tip/f0a97af83f6287357dcc100c859ec0066f164f32
Author: Andy Lutomirski
AuthorDate: Thu, 20 Aug 2015 22:03:21 -0700
Committer: Ingo Molnar
CommitDate: Sat, 22 Aug 2015 11:12:10 +0200
x86/traps: Weaken context tracking entry assertions
We were asserting that we were all the way in CONTEXT_KERNEL
when exception handlers were called. While having this be true
is, I think, a nice goal (or maybe a variant in which we assert
that we're in CONTEXT_KERNEL or some new IRQ context), we're not
quite there.
In particular, if an IRQ interrupts the SYSCALL prologue and the
IRQ handler in turn causes an exception, the exception entry
will be called in RCU IRQ mode but with CONTEXT_USER.
This is okay (nothing goes wrong), but until we fix up the
SYSCALL prologue, we need to avoid warning.
Signed-off-by: Andy Lutomirski
Acked-by: Frederic Weisbecker
Cc: Andy Lutomirski
Cc: Borislav Petkov
Cc: Brian Gerst
Cc: Denys Vlasenko
Cc: H. Peter Anvin
Cc: Linus Torvalds
Cc: Oleg Nesterov
Cc: Peter Zijlstra
Cc: Sasha Levin
Cc: Thomas Gleixner
Link:
http://lkml.kernel.org/r/c81faf3916346c0e04346c441392974f49cd7184.1440133286.git.l...@kernel.org
Signed-off-by: Ingo Molnar
---
arch/x86/kernel/traps.c | 18 +-
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 86a82ea..45e8d98 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -112,7 +112,7 @@ static inline void preempt_conditional_cli(struct pt_regs
*regs)
void ist_enter(struct pt_regs *regs)
{
if (user_mode(regs)) {
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), "entry code didn't wake
RCU");
} else {
/*
* We might have interrupted pretty much anything. In
@@ -282,7 +282,7 @@ static void do_error_trap(struct pt_regs *regs, long
error_code, char *str,
{
siginfo_t info;
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), "entry code didn't wake RCU");
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
NOTIFY_STOP) {
@@ -364,7 +364,7 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long
error_code)
const struct bndcsr *bndcsr;
siginfo_t *info;
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), "entry code didn't wake RCU");
if (notify_die(DIE_TRAP, "bounds", regs, error_code,
X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
return;
@@ -442,7 +442,7 @@ do_general_protection(struct pt_regs *regs, long error_code)
{
struct task_struct *tsk;
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), "entry code didn't wake RCU");
conditional_sti(regs);
if (v8086_mode(regs)) {
@@ -496,7 +496,7 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs,
long error_code)
return;
ist_enter(regs);
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), "entry code didn't wake RCU");
#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
SIGTRAP) == NOTIFY_STOP)
@@ -729,14 +729,14 @@ static void math_error(struct pt_regs *regs, int
error_code, int trapnr)
dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
{
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), "entry code didn't wake RCU");
math_error(regs, error_code, X86_TRAP_MF);
}
dotraplinkage void
do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
{
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), "entry code didn't wake RCU");
math_error(regs, error_code, X86_TRAP_XF);
}
@@ -749,7 +749,7 @@ do_spurious_interrupt_bug(struct pt_regs *regs, long
error_code)
dotraplinkage void
do_device_not_available(struct pt_regs *regs, long error_code)
{
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), "entry code didn't wake RCU");
BUG_ON(use_eager_fpu());
#ifdef CONFIG_MATH_EMULATION
@@ -775,7 +775,7 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long
error_code)
{
siginfo_t info;
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), "entry code didn't wake RCU");
local_irq_enable();
info.si_signo = SIGILL;
--
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[tip:core/core] x86/traps: Weaken context tracking entry assertions
Commit-ID: f0a97af83f6287357dcc100c859ec0066f164f32
Gitweb: http://git.kernel.org/tip/f0a97af83f6287357dcc100c859ec0066f164f32
Author: Andy Lutomirski l...@kernel.org
AuthorDate: Thu, 20 Aug 2015 22:03:21 -0700
Committer: Ingo Molnar mi...@kernel.org
CommitDate: Sat, 22 Aug 2015 11:12:10 +0200
x86/traps: Weaken context tracking entry assertions
We were asserting that we were all the way in CONTEXT_KERNEL
when exception handlers were called. While having this be true
is, I think, a nice goal (or maybe a variant in which we assert
that we're in CONTEXT_KERNEL or some new IRQ context), we're not
quite there.
In particular, if an IRQ interrupts the SYSCALL prologue and the
IRQ handler in turn causes an exception, the exception entry
will be called in RCU IRQ mode but with CONTEXT_USER.
This is okay (nothing goes wrong), but until we fix up the
SYSCALL prologue, we need to avoid warning.
Signed-off-by: Andy Lutomirski l...@kernel.org
Acked-by: Frederic Weisbecker fweis...@gmail.com
Cc: Andy Lutomirski l...@amacapital.net
Cc: Borislav Petkov b...@alien8.de
Cc: Brian Gerst brge...@gmail.com
Cc: Denys Vlasenko dvlas...@redhat.com
Cc: H. Peter Anvin h...@zytor.com
Cc: Linus Torvalds torva...@linux-foundation.org
Cc: Oleg Nesterov o...@redhat.com
Cc: Peter Zijlstra pet...@infradead.org
Cc: Sasha Levin sasha.le...@oracle.com
Cc: Thomas Gleixner t...@linutronix.de
Link:
http://lkml.kernel.org/r/c81faf3916346c0e04346c441392974f49cd7184.1440133286.git.l...@kernel.org
Signed-off-by: Ingo Molnar mi...@kernel.org
---
arch/x86/kernel/traps.c | 18 +-
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 86a82ea..45e8d98 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -112,7 +112,7 @@ static inline void preempt_conditional_cli(struct pt_regs
*regs)
void ist_enter(struct pt_regs *regs)
{
if (user_mode(regs)) {
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), entry code didn't wake
RCU);
} else {
/*
* We might have interrupted pretty much anything. In
@@ -282,7 +282,7 @@ static void do_error_trap(struct pt_regs *regs, long
error_code, char *str,
{
siginfo_t info;
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), entry code didn't wake RCU);
if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) !=
NOTIFY_STOP) {
@@ -364,7 +364,7 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long
error_code)
const struct bndcsr *bndcsr;
siginfo_t *info;
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), entry code didn't wake RCU);
if (notify_die(DIE_TRAP, bounds, regs, error_code,
X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP)
return;
@@ -442,7 +442,7 @@ do_general_protection(struct pt_regs *regs, long error_code)
{
struct task_struct *tsk;
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), entry code didn't wake RCU);
conditional_sti(regs);
if (v8086_mode(regs)) {
@@ -496,7 +496,7 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs,
long error_code)
return;
ist_enter(regs);
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), entry code didn't wake RCU);
#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
if (kgdb_ll_trap(DIE_INT3, int3, regs, error_code, X86_TRAP_BP,
SIGTRAP) == NOTIFY_STOP)
@@ -729,14 +729,14 @@ static void math_error(struct pt_regs *regs, int
error_code, int trapnr)
dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
{
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), entry code didn't wake RCU);
math_error(regs, error_code, X86_TRAP_MF);
}
dotraplinkage void
do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
{
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), entry code didn't wake RCU);
math_error(regs, error_code, X86_TRAP_XF);
}
@@ -749,7 +749,7 @@ do_spurious_interrupt_bug(struct pt_regs *regs, long
error_code)
dotraplinkage void
do_device_not_available(struct pt_regs *regs, long error_code)
{
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), entry code didn't wake RCU);
BUG_ON(use_eager_fpu());
#ifdef CONFIG_MATH_EMULATION
@@ -775,7 +775,7 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long
error_code)
{
siginfo_t info;
- CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+ rcu_lockdep_assert(rcu_is_watching(), entry code didn't wake RCU);
