From e45e8ddf3cfcc7eb756caa35d81c731282b5d0d1 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 22 Sep 2020 09:58:52 +0200 Subject: [PATCH] x86/irq: Make run_on_irqstack_cond() typesafe commit a7b3474cbb2864d5500d5e4f48dd57c903975cab upstream. 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 Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/common.c | 2 +- arch/x86/entry/entry_64.S | 2 + arch/x86/include/asm/idtentry.h | 2 +- arch/x86/include/asm/irq_stack.h | 70 ++++++++++++++++++++++++++++---- arch/x86/kernel/irq.c | 2 +- arch/x86/kernel/irq_64.c | 2 +- 6 files changed, 68 insertions(+), 12 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 606c4e25ee934..e290164df5ada 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -814,7 +814,7 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs) old_regs = set_irq_regs(regs); instrumentation_begin(); - run_on_irqstack_cond(__xen_pv_evtchn_do_upcall, NULL, regs); + run_on_irqstack_cond(__xen_pv_evtchn_do_upcall, regs); instrumentation_begin(); set_irq_regs(old_regs); diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index d2a00c97e53f6..20f62398477e5 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -687,6 +687,8 @@ SYM_CODE_END(.Lbad_gs) * rdx: Function argument (can be NULL if none) */ SYM_FUNC_START(asm_call_on_stack) +SYM_INNER_LABEL(asm_call_sysvec_on_stack, SYM_L_GLOBAL) +SYM_INNER_LABEL(asm_call_irq_on_stack, SYM_L_GLOBAL) /* * Save the frame pointer unconditionally. This allows the ORC * unwinder to handle the stack switch. diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index 80d3b30d3ee3e..4abe2e5b3fa76 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -246,7 +246,7 @@ __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(); \ idtentry_exit_cond_rcu(regs, rcu_exit); \ diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h index 4ae66f097101d..d95616c7e7d40 100644 --- a/arch/x86/include/asm/irq_stack.h +++ b/arch/x86/include/asm/irq_stack.h @@ -3,6 +3,7 @@ #define _ASM_X86_IRQ_STACK_H #include +#include #include @@ -12,20 +13,50 @@ 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 +68,40 @@ 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 diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 181060247e3cb..c5dd50369e2f3 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -227,7 +227,7 @@ static __always_inline void handle_irq(struct irq_desc *desc, struct pt_regs *regs) { if (IS_ENABLED(CONFIG_X86_64)) - run_on_irqstack_cond(desc->handle_irq, desc, regs); + run_irq_on_irqstack_cond(desc->handle_irq, desc, regs); else __handle_irq(desc, regs); } diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c index 1b4fe93a86c5c..440eed558558d 100644 --- a/arch/x86/kernel/irq_64.c +++ b/arch/x86/kernel/irq_64.c @@ -74,5 +74,5 @@ int irq_init_percpu_irqstack(unsigned int cpu) void do_softirq_own_stack(void) { - run_on_irqstack_cond(__do_softirq, NULL, NULL); + run_on_irqstack_cond(__do_softirq, NULL); } -- 2.47.3