| Message ID | 20180718211013.14512-2-labbott@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Laura, On Wed, Jul 18, 2018 at 02:10:12PM -0700, Laura Abbott wrote: > > In preparation for enabling the stackleak plugin on arm64, > we need a way to get the bounds of the current stack. > Introduce a new primitive current_stack_type which is similar > to x86's get_stack_info. Utilize that to rework > on_accessible_stack slightly as well. > > Signed-off-by: Laura Abbott <labbott@redhat.com> > --- > So this did end up looking quite a bit like get_stack_info but I didn't > really see the need to integrate this more than this. I do think > actually enumerating the types makes things a bit cleaner. > --- > arch/arm64/include/asm/sdei.h | 8 ++- > arch/arm64/include/asm/stacktrace.h | 94 ++++++++++++++++++++++++----- > arch/arm64/kernel/ptrace.c | 2 +- > arch/arm64/kernel/sdei.c | 21 ++++++- > 4 files changed, 103 insertions(+), 22 deletions(-) > > diff --git a/arch/arm64/include/asm/sdei.h b/arch/arm64/include/asm/sdei.h > index e073e6886685..34f7b203845b 100644 > --- a/arch/arm64/include/asm/sdei.h > +++ b/arch/arm64/include/asm/sdei.h > @@ -40,15 +40,17 @@ asmlinkage unsigned long __sdei_handler(struct pt_regs *regs, > unsigned long sdei_arch_get_entry_point(int conduit); > #define sdei_arch_get_entry_point(x) sdei_arch_get_entry_point(x) > > -bool _on_sdei_stack(unsigned long sp); > -static inline bool on_sdei_stack(unsigned long sp) > +bool _on_sdei_stack(unsigned long sp, unsigned long *, unsigned long *); > +static inline bool on_sdei_stack(unsigned long sp, > + unsigned long *stack_low, > + unsigned long *stack_high) > { > if (!IS_ENABLED(CONFIG_VMAP_STACK)) > return false; > if (!IS_ENABLED(CONFIG_ARM_SDE_INTERFACE)) > return false; > if (in_nmi()) > - return _on_sdei_stack(sp); > + return _on_sdei_stack(sp, stack_low, stack_high); > > return false; > } > diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h > index 902f9edacbea..9855a0425e64 100644 > --- a/arch/arm64/include/asm/stacktrace.h > +++ b/arch/arm64/include/asm/stacktrace.h > @@ -39,7 +39,9 @@ extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk); > > DECLARE_PER_CPU(unsigned long *, irq_stack_ptr); > > -static inline bool on_irq_stack(unsigned long sp) > +static inline bool on_irq_stack(unsigned long sp, > + unsigned long *stack_low, > + unsigned long *stack_high) > { > unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr); > unsigned long high = low + IRQ_STACK_SIZE; > @@ -47,47 +49,109 @@ static inline bool on_irq_stack(unsigned long sp) > if (!low) > return false; > > - return (low <= sp && sp < high); > + if (sp < low || sp >= high) > + return false; > + > + if (stack_low && stack_high) { > + *stack_low = low; > + *stack_high = high; > + } > + > + return true; > } Rather than having to pass separete pointers to low/high, could we please wrap them up as a struct, e.g. struct stack_info { unsigned long low, high; stack_type type; } ... and pass a single pointer to that? e.g. static inline bool on_irq_stack(unsigned long sp, struct stack_info *info) { unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr); unsigned long high = low + IRQ_STACK_SIZE; if (!low) return false; if (sp < low || sp >= high) return false; if (info) { info->low = low; info->high = high; info->type = STACK_TYPE_IRQ; } return true; } That simplified the prototypes, and will allow us to distinguish the two SDEI stacks (which we'll need for making stack unwiding robust to cross-stack loops). > -static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp) > +static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp, > + unsigned long *stack_low, > + unsigned long *stack_high) > { > unsigned long low = (unsigned long)task_stack_page(tsk); > unsigned long high = low + THREAD_SIZE; > > - return (low <= sp && sp < high); > + if (sp < low || sp >= high) > + return false; > + > + if (stack_low && stack_high) { > + *stack_low = low; > + *stack_high = high; > + } > + > + return true; > } > > #ifdef CONFIG_VMAP_STACK > DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack); > > -static inline bool on_overflow_stack(unsigned long sp) > +static inline bool on_overflow_stack(unsigned long sp, > + unsigned long *stack_low, > + unsigned long *stack_high) > { > unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack); > unsigned long high = low + OVERFLOW_STACK_SIZE; > > - return (low <= sp && sp < high); > + if (sp < low || sp >= high) > + return false; > + > + if (stack_low && stack_high) { > + *stack_low = low; > + *stack_high = high; > + } > + > + return true; > } > #else > -static inline bool on_overflow_stack(unsigned long sp) { return false; } > +static inline bool on_overflow_stack(unsigned long sp, > + unsigned long *stack_low, > + unsigned long *stack_high) { return false; } > #endif > > +enum stack_type { > + STACK_TYPE_UNKNOWN, > + STACK_TYPE_TASK, > + STACK_TYPE_IRQ, > + STACK_TYPE_OVERFLOW, > + STACK_TYPE_SDEI, > +}; For SDEI we'll need STACK_TYPE_SDEI_NORMAL and STACK_TYPE_SDEI_CRITICAL, at least for stack unwinding. > + > +static inline enum stack_type current_stack_type(struct task_struct *tsk, > + unsigned long sp, > + unsigned long *stack_low, > + unsigned long *stack_high) > +{ > + if (on_task_stack(tsk, sp, stack_low, stack_high)) > + return STACK_TYPE_TASK; > + if (on_irq_stack(sp, stack_low, stack_high)) > + return STACK_TYPE_IRQ; > + if (on_overflow_stack(sp, stack_low, stack_high)) > + return STACK_TYPE_OVERFLOW; > + if (on_sdei_stack(sp, stack_low, stack_high)) > + return STACK_TYPE_SDEI; > + return STACK_TYPE_UNKNOWN; > +} > + > /* > * We can only safely access per-cpu stacks from current in a non-preemptible > * context. > */ > static inline bool on_accessible_stack(struct task_struct *tsk, unsigned long sp) > { > - if (on_task_stack(tsk, sp)) > + enum stack_type type; > + unsigned long low, high; > + > + type = current_stack_type(tsk, sp, &low, &high); > + > + switch (type) { > + case STACK_TYPE_TASK: > return true; > - if (tsk != current || preemptible()) > + case STACK_TYPE_IRQ: > + case STACK_TYPE_OVERFLOW: > + case STACK_TYPE_SDEI: > + if (tsk != current || preemptible()) > + return false; > + else > + return true; > + case STACK_TYPE_UNKNOWN: > return false; > - if (on_irq_stack(sp)) > - return true; > - if (on_overflow_stack(sp)) > - return true; > - if (on_sdei_stack(sp)) > - return true; > + } > > return false; > } With the stacut stack_info, I think we can leave the logic of on_accessible_stack() as-is, modulo a new info parameter that we pass on into each on_<foo>_stack(), and then we don't neeed a separate current_stack_type() function. > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > index 5c338ce5a7fa..a6b3a2be7561 100644 > --- a/arch/arm64/kernel/ptrace.c > +++ b/arch/arm64/kernel/ptrace.c > @@ -132,7 +132,7 @@ static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr) > { > return ((addr & ~(THREAD_SIZE - 1)) == > (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1))) || > - on_irq_stack(addr); > + on_irq_stack(addr, NULL, NULL); > } > > /** > diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c > index 6b8d90d5ceae..8e18913a53fd 100644 > --- a/arch/arm64/kernel/sdei.c > +++ b/arch/arm64/kernel/sdei.c > @@ -88,7 +88,9 @@ static int init_sdei_stacks(void) > return err; > } > > -bool _on_sdei_stack(unsigned long sp) > +bool _on_sdei_stack(unsigned long sp, > + unsigned long *stack_low, > + unsigned long *stack_high) > { > unsigned long low, high; > > @@ -98,13 +100,26 @@ bool _on_sdei_stack(unsigned long sp) > low = (unsigned long)raw_cpu_read(sdei_stack_critical_ptr); > high = low + SDEI_STACK_SIZE; > > - if (low <= sp && sp < high) > + if (low <= sp && sp < high) { > + if (stack_low && stack_high) { > + *stack_low = low; > + *stack_high = high; > + } > return true; > + } > > low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr); > high = low + SDEI_STACK_SIZE; > > - return (low <= sp && sp < high); > + if (low <= sp && sp < high) { > + if (stack_low && stack_high) { > + *stack_low = low; > + *stack_high = high; > + } > + return true; > + } > + > + return false; > } We should probably split this into separate on_sdei_normal_stack() and on_sdei_critical_stack() functions. Then we can do: bool on_sdei_<foo>_stack(...) { if (<out of bounds>) return false; if (info) { <assign info fields>; } return true; } bool _on_sdei_stack(unsigned long sp, struct stack_info *info) { if (on_sedi_critical_stack(sp, info)) return true; if (on_sdei_normal_stack(sp, info)) return true; return false; } ... which is a little nicer for legibility. Otherwise, this looks good to me. Thanks, Mark.
diff --git a/arch/arm64/include/asm/sdei.h b/arch/arm64/include/asm/sdei.h index e073e6886685..34f7b203845b 100644 --- a/arch/arm64/include/asm/sdei.h +++ b/arch/arm64/include/asm/sdei.h @@ -40,15 +40,17 @@ asmlinkage unsigned long __sdei_handler(struct pt_regs *regs, unsigned long sdei_arch_get_entry_point(int conduit); #define sdei_arch_get_entry_point(x) sdei_arch_get_entry_point(x) -bool _on_sdei_stack(unsigned long sp); -static inline bool on_sdei_stack(unsigned long sp) +bool _on_sdei_stack(unsigned long sp, unsigned long *, unsigned long *); +static inline bool on_sdei_stack(unsigned long sp, + unsigned long *stack_low, + unsigned long *stack_high) { if (!IS_ENABLED(CONFIG_VMAP_STACK)) return false; if (!IS_ENABLED(CONFIG_ARM_SDE_INTERFACE)) return false; if (in_nmi()) - return _on_sdei_stack(sp); + return _on_sdei_stack(sp, stack_low, stack_high); return false; } diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h index 902f9edacbea..9855a0425e64 100644 --- a/arch/arm64/include/asm/stacktrace.h +++ b/arch/arm64/include/asm/stacktrace.h @@ -39,7 +39,9 @@ extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk); DECLARE_PER_CPU(unsigned long *, irq_stack_ptr); -static inline bool on_irq_stack(unsigned long sp) +static inline bool on_irq_stack(unsigned long sp, + unsigned long *stack_low, + unsigned long *stack_high) { unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr); unsigned long high = low + IRQ_STACK_SIZE; @@ -47,47 +49,109 @@ static inline bool on_irq_stack(unsigned long sp) if (!low) return false; - return (low <= sp && sp < high); + if (sp < low || sp >= high) + return false; + + if (stack_low && stack_high) { + *stack_low = low; + *stack_high = high; + } + + return true; } -static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp) +static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp, + unsigned long *stack_low, + unsigned long *stack_high) { unsigned long low = (unsigned long)task_stack_page(tsk); unsigned long high = low + THREAD_SIZE; - return (low <= sp && sp < high); + if (sp < low || sp >= high) + return false; + + if (stack_low && stack_high) { + *stack_low = low; + *stack_high = high; + } + + return true; } #ifdef CONFIG_VMAP_STACK DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack); -static inline bool on_overflow_stack(unsigned long sp) +static inline bool on_overflow_stack(unsigned long sp, + unsigned long *stack_low, + unsigned long *stack_high) { unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack); unsigned long high = low + OVERFLOW_STACK_SIZE; - return (low <= sp && sp < high); + if (sp < low || sp >= high) + return false; + + if (stack_low && stack_high) { + *stack_low = low; + *stack_high = high; + } + + return true; } #else -static inline bool on_overflow_stack(unsigned long sp) { return false; } +static inline bool on_overflow_stack(unsigned long sp, + unsigned long *stack_low, + unsigned long *stack_high) { return false; } #endif +enum stack_type { + STACK_TYPE_UNKNOWN, + STACK_TYPE_TASK, + STACK_TYPE_IRQ, + STACK_TYPE_OVERFLOW, + STACK_TYPE_SDEI, +}; + +static inline enum stack_type current_stack_type(struct task_struct *tsk, + unsigned long sp, + unsigned long *stack_low, + unsigned long *stack_high) +{ + if (on_task_stack(tsk, sp, stack_low, stack_high)) + return STACK_TYPE_TASK; + if (on_irq_stack(sp, stack_low, stack_high)) + return STACK_TYPE_IRQ; + if (on_overflow_stack(sp, stack_low, stack_high)) + return STACK_TYPE_OVERFLOW; + if (on_sdei_stack(sp, stack_low, stack_high)) + return STACK_TYPE_SDEI; + return STACK_TYPE_UNKNOWN; +} + /* * We can only safely access per-cpu stacks from current in a non-preemptible * context. */ static inline bool on_accessible_stack(struct task_struct *tsk, unsigned long sp) { - if (on_task_stack(tsk, sp)) + enum stack_type type; + unsigned long low, high; + + type = current_stack_type(tsk, sp, &low, &high); + + switch (type) { + case STACK_TYPE_TASK: return true; - if (tsk != current || preemptible()) + case STACK_TYPE_IRQ: + case STACK_TYPE_OVERFLOW: + case STACK_TYPE_SDEI: + if (tsk != current || preemptible()) + return false; + else + return true; + case STACK_TYPE_UNKNOWN: return false; - if (on_irq_stack(sp)) - return true; - if (on_overflow_stack(sp)) - return true; - if (on_sdei_stack(sp)) - return true; + } return false; } diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index 5c338ce5a7fa..a6b3a2be7561 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -132,7 +132,7 @@ static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr) { return ((addr & ~(THREAD_SIZE - 1)) == (kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1))) || - on_irq_stack(addr); + on_irq_stack(addr, NULL, NULL); } /** diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c index 6b8d90d5ceae..8e18913a53fd 100644 --- a/arch/arm64/kernel/sdei.c +++ b/arch/arm64/kernel/sdei.c @@ -88,7 +88,9 @@ static int init_sdei_stacks(void) return err; } -bool _on_sdei_stack(unsigned long sp) +bool _on_sdei_stack(unsigned long sp, + unsigned long *stack_low, + unsigned long *stack_high) { unsigned long low, high; @@ -98,13 +100,26 @@ bool _on_sdei_stack(unsigned long sp) low = (unsigned long)raw_cpu_read(sdei_stack_critical_ptr); high = low + SDEI_STACK_SIZE; - if (low <= sp && sp < high) + if (low <= sp && sp < high) { + if (stack_low && stack_high) { + *stack_low = low; + *stack_high = high; + } return true; + } low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr); high = low + SDEI_STACK_SIZE; - return (low <= sp && sp < high); + if (low <= sp && sp < high) { + if (stack_low && stack_high) { + *stack_low = low; + *stack_high = high; + } + return true; + } + + return false; } unsigned long sdei_arch_get_entry_point(int conduit)
In preparation for enabling the stackleak plugin on arm64, we need a way to get the bounds of the current stack. Introduce a new primitive current_stack_type which is similar to x86's get_stack_info. Utilize that to rework on_accessible_stack slightly as well. Signed-off-by: Laura Abbott <labbott@redhat.com> --- So this did end up looking quite a bit like get_stack_info but I didn't really see the need to integrate this more than this. I do think actually enumerating the types makes things a bit cleaner. --- arch/arm64/include/asm/sdei.h | 8 ++- arch/arm64/include/asm/stacktrace.h | 94 ++++++++++++++++++++++++----- arch/arm64/kernel/ptrace.c | 2 +- arch/arm64/kernel/sdei.c | 21 ++++++- 4 files changed, 103 insertions(+), 22 deletions(-)