Messages in this thread Patch in this message | | | From | Alexandre Chartre <> | Subject | [RFC][PATCH v2 15/21] x86/pti: Execute IDT handlers with error code on the kernel stack | Date | Mon, 16 Nov 2020 15:47:51 +0100 |
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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
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