Messages in this thread | | | Date | Thu, 19 Nov 2020 13:11:18 +0000 | From | Will Deacon <> | Subject | Re: [PATCH 2/2] arm64: scs: use vmapped IRQ and SDEI shadow stacks |
| |
On Thu, Oct 22, 2020 at 01:23:55PM -0700, Sami Tolvanen wrote: > Use scs_alloc() to allocate also IRQ and SDEI shadow stacks instead of > using statically allocated stacks. > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > --- > arch/arm64/include/asm/scs.h | 21 ++++++++++- > arch/arm64/kernel/entry.S | 6 ++-- > arch/arm64/kernel/irq.c | 2 ++ > arch/arm64/kernel/scs.c | 67 +++++++++++++++++++++++++++++++++--- > arch/arm64/kernel/sdei.c | 7 ++++ > include/linux/scs.h | 8 ++--- > kernel/scs.c | 4 +-- > 7 files changed, 101 insertions(+), 14 deletions(-) > > diff --git a/arch/arm64/include/asm/scs.h b/arch/arm64/include/asm/scs.h > index eaa2cd92e4c1..e9d2c3e67ff9 100644 > --- a/arch/arm64/include/asm/scs.h > +++ b/arch/arm64/include/asm/scs.h > @@ -24,6 +24,25 @@ > .endm > #endif /* CONFIG_SHADOW_CALL_STACK */ > > -#endif /* __ASSEMBLY __ */ > +#else /* __ASSEMBLY__ */ > + > +#include <linux/scs.h> > + > +#ifdef CONFIG_SHADOW_CALL_STACK > + > +extern void scs_init_irq(void); > + > +extern void scs_free_sdei(void);
This is only called on the scs_init_sdei() failure path, so it can be static. But see below, because I think we should move all of these functions out of scs.c anyway.
> diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c > index 9cf2fb87584a..54ba3725bc0e 100644 > --- a/arch/arm64/kernel/irq.c > +++ b/arch/arm64/kernel/irq.c > @@ -20,6 +20,7 @@ > #include <linux/seq_file.h> > #include <linux/vmalloc.h> > #include <asm/daifflags.h> > +#include <asm/scs.h> > #include <asm/vmap_stack.h> > > /* Only access this in an NMI enter/exit */ > @@ -54,6 +55,7 @@ static void init_irq_stacks(void) > void __init init_IRQ(void) > { > init_irq_stacks(); > + scs_init_irq();
If we internalise this in init_irq_stacks()...
> diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c > index 7689f2031c0c..04519a7cb51d 100644 > --- a/arch/arm64/kernel/sdei.c > +++ b/arch/arm64/kernel/sdei.c > @@ -13,6 +13,7 @@ > #include <asm/kprobes.h> > #include <asm/mmu.h> > #include <asm/ptrace.h> > +#include <asm/scs.h> > #include <asm/sections.h> > #include <asm/stacktrace.h> > #include <asm/sysreg.h> > @@ -138,6 +139,12 @@ unsigned long sdei_arch_get_entry_point(int conduit) > return 0; > } > > + if (scs_init_sdei()) {
... and this in init_sdei_stacks(), then I think we remove all of the code from arch/arm64/kernel/scs.c.
> diff --git a/include/linux/scs.h b/include/linux/scs.h > index 86e3c4b7b714..6b35a83576d4 100644 > --- a/include/linux/scs.h > +++ b/include/linux/scs.h > @@ -21,13 +21,11 @@ > /* An illegal pointer value to mark the end of the shadow stack. */ > #define SCS_END_MAGIC (0x5f6UL + POISON_POINTER_DELTA) > > -/* Allocate a static per-CPU shadow stack */ > -#define DEFINE_SCS(name) \ > - DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], name) \ > - > #define task_scs(tsk) (task_thread_info(tsk)->scs_base) > #define task_scs_sp(tsk) (task_thread_info(tsk)->scs_sp) > > +void *scs_alloc(int node); > +void scs_free(void *s); > void scs_init(void); > int scs_prepare(struct task_struct *tsk, int node); > void scs_release(struct task_struct *tsk); > @@ -56,6 +54,8 @@ static inline bool task_scs_end_corrupted(struct task_struct *tsk) > > #else /* CONFIG_SHADOW_CALL_STACK */ > > +static inline void *scs_alloc(int node) { return NULL; } > +static inline void scs_free(void *s) {} > static inline void scs_init(void) {} > static inline void scs_task_reset(struct task_struct *tsk) {} > static inline int scs_prepare(struct task_struct *tsk, int node) { return 0; } > diff --git a/kernel/scs.c b/kernel/scs.c > index 2136edba548d..8df4a92cd939 100644 > --- a/kernel/scs.c > +++ b/kernel/scs.c > @@ -24,7 +24,7 @@ static void __scs_account(void *s, int account) > #define NR_CACHED_SCS 2 > static DEFINE_PER_CPU(void *, scs_cache[NR_CACHED_SCS]); > > -static void *scs_alloc(int node) > +void *scs_alloc(int node) > { > int i; > void *s; > @@ -63,7 +63,7 @@ static void *scs_alloc(int node) > return s; > } > > -static void scs_free(void *s) > +void scs_free(void *s)
Should be part of the first patch?
Will
| |