From a7b3474cbb2864d5500d5e4f48dd57c903975cab Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 22 Sep 2020 09:58:52 +0200 Subject: x86/irq: Make run_on_irqstack_cond() typesafe Sami reported that run_on_irqstack_cond() requires the caller to cast functions to mismatching types, which trips indirect call Control-Flow Integrity (CFI) in Clang. Instead of disabling CFI on that function, provide proper helpers for the three call variants. The actual ASM code stays the same as that is out of reach. [ bp: Fix __run_on_irqstack() prototype to match. ] Fixes: 931b94145981 ("x86/entry: Provide helpers for executing on the irqstack") Reported-by: Nathan Chancellor Reported-by: Sami Tolvanen Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Tested-by: Sami Tolvanen Cc: Link: https://github.com/ClangBuiltLinux/linux/issues/1052 Link: https://lkml.kernel.org/r/87pn6eb5tv.fsf@nanos.tec.linutronix.de --- arch/x86/include/asm/idtentry.h | 2 +- arch/x86/include/asm/irq_stack.h | 69 +++++++++++++++++++++++++++++++++++----- 2 files changed, 62 insertions(+), 9 deletions(-) (limited to 'arch/x86/include/asm') diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index a43366191212..a0638640f1ed 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -242,7 +242,7 @@ __visible noinstr void func(struct pt_regs *regs) \ instrumentation_begin(); \ irq_enter_rcu(); \ kvm_set_cpu_l1tf_flush_l1d(); \ - run_on_irqstack_cond(__##func, regs, regs); \ + run_sysvec_on_irqstack_cond(__##func, regs); \ irq_exit_rcu(); \ instrumentation_end(); \ irqentry_exit(regs, state); \ diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h index 4ae66f097101..775816965c6a 100644 --- a/arch/x86/include/asm/irq_stack.h +++ b/arch/x86/include/asm/irq_stack.h @@ -12,20 +12,50 @@ static __always_inline bool irqstack_active(void) return __this_cpu_read(irq_count) != -1; } -void asm_call_on_stack(void *sp, void *func, void *arg); +void asm_call_on_stack(void *sp, void (*func)(void), void *arg); +void asm_call_sysvec_on_stack(void *sp, void (*func)(struct pt_regs *regs), + struct pt_regs *regs); +void asm_call_irq_on_stack(void *sp, void (*func)(struct irq_desc *desc), + struct irq_desc *desc); -static __always_inline void __run_on_irqstack(void *func, void *arg) +static __always_inline void __run_on_irqstack(void (*func)(void)) { void *tos = __this_cpu_read(hardirq_stack_ptr); __this_cpu_add(irq_count, 1); - asm_call_on_stack(tos - 8, func, arg); + asm_call_on_stack(tos - 8, func, NULL); + __this_cpu_sub(irq_count, 1); +} + +static __always_inline void +__run_sysvec_on_irqstack(void (*func)(struct pt_regs *regs), + struct pt_regs *regs) +{ + void *tos = __this_cpu_read(hardirq_stack_ptr); + + __this_cpu_add(irq_count, 1); + asm_call_sysvec_on_stack(tos - 8, func, regs); + __this_cpu_sub(irq_count, 1); +} + +static __always_inline void +__run_irq_on_irqstack(void (*func)(struct irq_desc *desc), + struct irq_desc *desc) +{ + void *tos = __this_cpu_read(hardirq_stack_ptr); + + __this_cpu_add(irq_count, 1); + asm_call_irq_on_stack(tos - 8, func, desc); __this_cpu_sub(irq_count, 1); } #else /* CONFIG_X86_64 */ static inline bool irqstack_active(void) { return false; } -static inline void __run_on_irqstack(void *func, void *arg) { } +static inline void __run_on_irqstack(void (*func)(void)) { } +static inline void __run_sysvec_on_irqstack(void (*func)(struct pt_regs *regs), + struct pt_regs *regs) { } +static inline void __run_irq_on_irqstack(void (*func)(struct irq_desc *desc), + struct irq_desc *desc) { } #endif /* !CONFIG_X86_64 */ static __always_inline bool irq_needs_irq_stack(struct pt_regs *regs) @@ -37,17 +67,40 @@ static __always_inline bool irq_needs_irq_stack(struct pt_regs *regs) return !user_mode(regs) && !irqstack_active(); } -static __always_inline void run_on_irqstack_cond(void *func, void *arg, + +static __always_inline void run_on_irqstack_cond(void (*func)(void), struct pt_regs *regs) { - void (*__func)(void *arg) = func; + lockdep_assert_irqs_disabled(); + + if (irq_needs_irq_stack(regs)) + __run_on_irqstack(func); + else + func(); +} + +static __always_inline void +run_sysvec_on_irqstack_cond(void (*func)(struct pt_regs *regs), + struct pt_regs *regs) +{ + lockdep_assert_irqs_disabled(); + if (irq_needs_irq_stack(regs)) + __run_sysvec_on_irqstack(func, regs); + else + func(regs); +} + +static __always_inline void +run_irq_on_irqstack_cond(void (*func)(struct irq_desc *desc), struct irq_desc *desc, + struct pt_regs *regs) +{ lockdep_assert_irqs_disabled(); if (irq_needs_irq_stack(regs)) - __run_on_irqstack(__func, arg); + __run_irq_on_irqstack(func, desc); else - __func(arg); + func(desc); } #endif -- cgit v1.2.3