From: Alexandre Chartre <alexandre.chartre@oracle.com>
To: "tglx@linutronix.de"@userv0121.oracle.com,
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Subject: [RFC][PATCH 17/24] x86/pti: Execute IDT handlers with error code on the kernel stack
Date: Mon, 9 Nov 2020 12:23:12 +0100 [thread overview]
Message-ID: <20201109112319.264511-18-alexandre.chartre@oracle.com> (raw)
In-Reply-To: <20201109112319.264511-1-alexandre.chartre@oracle.com>
After an interrupt/exception in userland, the kernel is entered
and it switches the stack to the PTI stack which is mapped both in
the kernel and in the user page-table. When executing the interrupt
function, switch to the kernel stack (which is mapped only in the
kernel page-table) so that no kernel data leak to the userland
through the stack.
Changes IDT handlers which have an error code.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
arch/x86/include/asm/idtentry.h | 18 ++++++++++++++++--
arch/x86/kernel/traps.c | 2 +-
2 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 3595a31947b3..a82e31b45442 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -25,6 +25,12 @@ void idtentry_exit_nmi(struct pt_regs *regs, bool irq_state);
(void (*)(void))(func), (void *)(arg1)) : \
func(arg1))
+#define CALL_ON_STACK_2(stack, func, arg1, arg2) \
+ ((stack) ? \
+ asm_call_on_stack_2(stack, \
+ (void (*)(void))(func), (void *)(arg1), (void *)(arg2)) : \
+ func(arg1, arg2))
+
/*
* Functions to return the top of the kernel stack if we are using the
* user page-table (and thus not running with the kernel stack). If we
@@ -53,6 +59,13 @@ void run_idt(void (*func)(struct pt_regs *), struct pt_regs *regs)
CALL_ON_STACK_1(pti_kernel_stack(regs), func, regs);
}
+static __always_inline
+void run_idt_errcode(void (*func)(struct pt_regs *, unsigned long),
+ struct pt_regs *regs, unsigned long error_code)
+{
+ CALL_ON_STACK_2(pti_kernel_stack(regs), func, regs, error_code);
+}
+
/**
* DECLARE_IDTENTRY - Declare functions for simple IDT entry points
* No error code pushed by hardware
@@ -141,7 +154,7 @@ __visible noinstr void func(struct pt_regs *regs, \
irqentry_state_t state = irqentry_enter(regs); \
\
instrumentation_begin(); \
- __##func (regs, error_code); \
+ run_idt_errcode(__##func, regs, error_code); \
instrumentation_end(); \
irqentry_exit(regs, state); \
} \
@@ -239,7 +252,8 @@ __visible noinstr void func(struct pt_regs *regs, \
instrumentation_begin(); \
irq_enter_rcu(); \
kvm_set_cpu_l1tf_flush_l1d(); \
- __##func (regs, (u8)error_code); \
+ run_idt_errcode((void (*)(struct pt_regs *, unsigned long))__##func, \
+ regs, (u8)error_code); \
irq_exit_rcu(); \
instrumentation_end(); \
irqentry_exit(regs, state); \
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 5161385b3670..9a51aa016fb3 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -979,7 +979,7 @@ DEFINE_IDTENTRY_DEBUG(exc_debug)
/* User entry, runs on regular task stack */
DEFINE_IDTENTRY_DEBUG_USER(exc_debug)
{
- exc_debug_user(regs, debug_read_clear_dr6());
+ run_idt_errcode(exc_debug_user, regs, debug_read_clear_dr6());
}
#else
/* 32 bit does not have separate entry points. */
--
2.18.4
next prev parent reply other threads:[~2020-11-09 11:23 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-09 11:22 [RFC][PATCH 00/24] x86/pti: Defer CR3 switch to C code Alexandre Chartre
2020-11-09 11:22 ` [RFC][PATCH 01/24] x86/syscall: Add wrapper for invoking syscall function Alexandre Chartre
2020-11-09 17:25 ` Andy Lutomirski
2020-11-09 17:45 ` Alexandre Chartre
2020-11-09 11:22 ` [RFC][PATCH 02/24] x86/entry: Update asm_call_on_stack to support more function arguments Alexandre Chartre
2020-11-09 11:22 ` [RFC][PATCH 03/24] x86/entry: Consolidate IST entry from userspace Alexandre Chartre
2020-11-09 11:22 ` [RFC][PATCH 04/24] x86/sev-es: Define a setup stack function for the VC idtentry Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 05/24] x86/entry: Implement ret_from_fork body with C code Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 06/24] x86/pti: Provide C variants of PTI switch CR3 macros Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 07/24] x86/entry: Fill ESPFIX stack using C code Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 08/24] x86/entry: Add C version of SWAPGS and SWAPGS_UNSAFE_STACK Alexandre Chartre
2020-11-09 17:38 ` Andy Lutomirski
2020-11-09 18:04 ` Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 09/24] x86/entry: Add C version of paranoid_entry/exit Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 10/24] x86/pti: Introduce per-task PTI trampoline stack Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 11/24] x86/pti: Function to clone page-table entries from a specified mm Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 12/24] x86/pti: Function to map per-cpu page-table entry Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 13/24] x86/pti: Extend PTI user mappings Alexandre Chartre
2020-11-09 17:28 ` Andy Lutomirski
2020-11-09 17:52 ` Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 14/24] x86/pti: Use PTI stack instead of trampoline stack Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 15/24] x86/pti: Execute syscall functions on the kernel stack Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 16/24] x86/pti: Execute IDT handlers " Alexandre Chartre
2020-11-09 11:23 ` Alexandre Chartre [this message]
2020-11-09 11:23 ` [RFC][PATCH 18/24] x86/pti: Execute system vector " Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 19/24] x86/pti: Execute page fault handler " Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 20/24] x86/pti: Execute NMI " Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 21/24] x86/entry: Disable stack-protector for IST entry C handlers Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 22/24] x86/entry: Defer paranoid entry/exit to C code Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 23/24] x86/entry: Remove paranoid_entry and paranoid_exit Alexandre Chartre
2020-11-09 11:23 ` [RFC][PATCH 24/24] x86/pti: Defer CR3 switch to C code for non-IST and syscall entries Alexandre Chartre
2020-11-09 14:00 ` [RFC][PATCH 00/24] x86/pti: Defer CR3 switch to C code Alexandre Chartre
2020-11-09 14:44 Alexandre Chartre
2020-11-09 14:44 ` [RFC][PATCH 17/24] x86/pti: Execute IDT handlers with error code on the kernel stack Alexandre Chartre
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