132 lines
4.9 KiB
Diff
132 lines
4.9 KiB
Diff
From: Andy Lutomirski <luto@amacapital.net>
|
|
Date: Sat, 22 Nov 2014 18:00:32 -0800
|
|
Subject: x86_64, traps: Stop using IST for #SS
|
|
Origin: https://git.kernel.org/linus/6f442be2fb22be02cafa606f1769fa1e6f894441
|
|
|
|
On a 32-bit kernel, this has no effect, since there are no IST stacks.
|
|
|
|
On a 64-bit kernel, #SS can only happen in user code, on a failed iret
|
|
to user space, a canonical violation on access via RSP or RBP, or a
|
|
genuine stack segment violation in 32-bit kernel code. The first two
|
|
cases don't need IST, and the latter two cases are unlikely fatal bugs,
|
|
and promoting them to double faults would be fine.
|
|
|
|
This fixes a bug in which the espfix64 code mishandles a stack segment
|
|
violation.
|
|
|
|
This saves 4k of memory per CPU and a tiny bit of code.
|
|
|
|
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
|
|
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
|
|
Cc: stable@vger.kernel.org
|
|
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
---
|
|
arch/x86/include/asm/page_32_types.h | 1 -
|
|
arch/x86/include/asm/page_64_types.h | 11 +++++------
|
|
arch/x86/include/asm/traps.h | 1 +
|
|
arch/x86/kernel/dumpstack_64.c | 1 -
|
|
arch/x86/kernel/entry_64.S | 2 +-
|
|
arch/x86/kernel/traps.c | 18 +-----------------
|
|
6 files changed, 8 insertions(+), 26 deletions(-)
|
|
|
|
--- a/arch/x86/include/asm/page_32_types.h
|
|
+++ b/arch/x86/include/asm/page_32_types.h
|
|
@@ -20,7 +20,6 @@
|
|
#define THREAD_SIZE_ORDER 1
|
|
#define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
|
|
|
|
-#define STACKFAULT_STACK 0
|
|
#define DOUBLEFAULT_STACK 1
|
|
#define NMI_STACK 0
|
|
#define DEBUG_STACK 0
|
|
--- a/arch/x86/include/asm/page_64_types.h
|
|
+++ b/arch/x86/include/asm/page_64_types.h
|
|
@@ -14,12 +14,11 @@
|
|
#define IRQ_STACK_ORDER 2
|
|
#define IRQ_STACK_SIZE (PAGE_SIZE << IRQ_STACK_ORDER)
|
|
|
|
-#define STACKFAULT_STACK 1
|
|
-#define DOUBLEFAULT_STACK 2
|
|
-#define NMI_STACK 3
|
|
-#define DEBUG_STACK 4
|
|
-#define MCE_STACK 5
|
|
-#define N_EXCEPTION_STACKS 5 /* hw limit: 7 */
|
|
+#define DOUBLEFAULT_STACK 1
|
|
+#define NMI_STACK 2
|
|
+#define DEBUG_STACK 3
|
|
+#define MCE_STACK 4
|
|
+#define N_EXCEPTION_STACKS 4 /* hw limit: 7 */
|
|
|
|
#define PUD_PAGE_SIZE (_AC(1, UL) << PUD_SHIFT)
|
|
#define PUD_PAGE_MASK (~(PUD_PAGE_SIZE-1))
|
|
--- a/arch/x86/include/asm/traps.h
|
|
+++ b/arch/x86/include/asm/traps.h
|
|
@@ -39,6 +39,7 @@ asmlinkage void simd_coprocessor_error(v
|
|
|
|
#ifdef CONFIG_TRACING
|
|
asmlinkage void trace_page_fault(void);
|
|
+#define trace_stack_segment stack_segment
|
|
#define trace_divide_error divide_error
|
|
#define trace_bounds bounds
|
|
#define trace_invalid_op invalid_op
|
|
--- a/arch/x86/kernel/dumpstack_64.c
|
|
+++ b/arch/x86/kernel/dumpstack_64.c
|
|
@@ -24,7 +24,6 @@ static char x86_stack_ids[][8] = {
|
|
[ DEBUG_STACK-1 ] = "#DB",
|
|
[ NMI_STACK-1 ] = "NMI",
|
|
[ DOUBLEFAULT_STACK-1 ] = "#DF",
|
|
- [ STACKFAULT_STACK-1 ] = "#SS",
|
|
[ MCE_STACK-1 ] = "#MC",
|
|
#if DEBUG_STKSZ > EXCEPTION_STKSZ
|
|
[ N_EXCEPTION_STACKS ...
|
|
--- a/arch/x86/kernel/entry_64.S
|
|
+++ b/arch/x86/kernel/entry_64.S
|
|
@@ -1321,7 +1321,7 @@ apicinterrupt3 HYPERVISOR_CALLBACK_VECTO
|
|
|
|
idtentry debug do_debug has_error_code=0 paranoid=1 shift_ist=DEBUG_STACK
|
|
idtentry int3 do_int3 has_error_code=0 paranoid=1 shift_ist=DEBUG_STACK
|
|
-idtentry stack_segment do_stack_segment has_error_code=1 paranoid=1
|
|
+idtentry stack_segment do_stack_segment has_error_code=1
|
|
#ifdef CONFIG_XEN
|
|
idtentry xen_debug do_debug has_error_code=0
|
|
idtentry xen_int3 do_int3 has_error_code=0
|
|
--- a/arch/x86/kernel/traps.c
|
|
+++ b/arch/x86/kernel/traps.c
|
|
@@ -233,27 +233,11 @@ DO_ERROR(X86_TRAP_UD, SIGILL, "inva
|
|
DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",coprocessor_segment_overrun)
|
|
DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS)
|
|
DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present)
|
|
-#ifdef CONFIG_X86_32
|
|
DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment)
|
|
-#endif
|
|
DO_ERROR(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check)
|
|
|
|
#ifdef CONFIG_X86_64
|
|
/* Runs on IST stack */
|
|
-dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
|
|
-{
|
|
- enum ctx_state prev_state;
|
|
-
|
|
- prev_state = exception_enter();
|
|
- if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
|
|
- X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
|
|
- preempt_conditional_sti(regs);
|
|
- do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
|
|
- preempt_conditional_cli(regs);
|
|
- }
|
|
- exception_exit(prev_state);
|
|
-}
|
|
-
|
|
dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
|
|
{
|
|
static const char str[] = "double fault";
|
|
@@ -778,7 +762,7 @@ void __init trap_init(void)
|
|
set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun);
|
|
set_intr_gate(X86_TRAP_TS, invalid_TSS);
|
|
set_intr_gate(X86_TRAP_NP, segment_not_present);
|
|
- set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK);
|
|
+ set_intr_gate(X86_TRAP_SS, stack_segment);
|
|
set_intr_gate(X86_TRAP_GP, general_protection);
|
|
set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug);
|
|
set_intr_gate(X86_TRAP_MF, coprocessor_error);
|