On Mon, 2022-10-31 at 15:54 +1000, Nicholas Piggin wrote:
> Most callers just want to validate an arbitrary kernel stack pointer,
> some need a particular size. Make the size case the exceptional one
> with an extra function.
>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
> ---
> arch/powerpc/include/asm/processor.h | 15 ++++++++++++---
> arch/powerpc/kernel/process.c | 23 ++++++++++++++---------
> arch/powerpc/kernel/stacktrace.c | 2 +-
> arch/powerpc/perf/callchain.c | 6 +++---
> 4 files changed, 30 insertions(+), 16 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/processor.h
> b/arch/powerpc/include/asm/processor.h
> index 631802999d59..e96c9b8c2a60 100644
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -374,9 +374,18 @@ static inline unsigned long __pack_fe01(unsigned
> int fpmode)
>
> #endif
>
> -/* Check that a certain kernel stack pointer is valid in task_struct
> p */
> -int validate_sp(unsigned long sp, struct task_struct *p,
> - unsigned long nbytes);
> +/*
> + * Check that a certain kernel stack pointer is a valid (minimum
> sized)
> + * stack frame in task_struct p.
> + */
> +int validate_sp(unsigned long sp, struct task_struct *p);
> +
> +/*
> + * validate the stack frame of a particular minimum size, used for
> when we are
> + * looking at a certain object in the stack beyond the minimum.
> + */
> +int validate_sp_size(unsigned long sp, struct task_struct *p,
> + unsigned long nbytes);
>
> /*
> * Prefetch macros.
> diff --git a/arch/powerpc/kernel/process.c
> b/arch/powerpc/kernel/process.c
> index 6cb3982a11ef..b5defea32e75 100644
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -2128,9 +2128,12 @@ static inline int
> valid_emergency_stack(unsigned long sp, struct task_struct *p,
> return 0;
> }
>
> -
> -int validate_sp(unsigned long sp, struct task_struct *p,
> - unsigned long nbytes)
> +/*
> + * validate the stack frame of a particular minimum size, used for
> when we are
> + * looking at a certain object in the stack beyond the minimum.
> + */
> +int validate_sp_size(unsigned long sp, struct task_struct *p,
> + unsigned long nbytes)
> {
> unsigned long stack_page = (unsigned long)task_stack_page(p);
>
> @@ -2146,7 +2149,10 @@ int validate_sp(unsigned long sp, struct
> task_struct *p,
> return valid_emergency_stack(sp, p, nbytes);
> }
>
> -EXPORT_SYMBOL(validate_sp);
> +int validate_sp(unsigned long sp, struct task_struct *p)
> +{
> + return validate_sp(sp, p, STACK_FRAME_OVERHEAD);
Hi Nick, I assume this supposed to be validate_sp_size()? Did you get
this to compile?
> +}
>
> static unsigned long ___get_wchan(struct task_struct *p)
> {
> @@ -2154,13 +2160,12 @@ static unsigned long ___get_wchan(struct
> task_struct *p)
> int count = 0;
>
> sp = p->thread.ksp;
> - if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD))
> + if (!validate_sp(sp, p))
> return 0;
>
> do {
> sp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
> - if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD) ||
> - task_is_running(p))
> + if (!validate_sp(sp, p) || task_is_running(p))
> return 0;
> if (count > 0) {
> ip = READ_ONCE_NOCHECK(((unsigned long
> *)sp)[STACK_FRAME_LR_SAVE]);
> @@ -2214,7 +2219,7 @@ void __no_sanitize_address show_stack(struct
> task_struct *tsk,
> lr = 0;
> printk("%sCall Trace:\n", loglvl);
> do {
> - if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
> + if (!validate_sp(sp, tsk))
> break;
>
> stack = (unsigned long *) sp;
> @@ -2241,7 +2246,7 @@ void __no_sanitize_address show_stack(struct
> task_struct *tsk,
> * could hold a pt_regs, if that does not fit then it
> can't
> * have regs.
> */
> - if (validate_sp(sp, tsk, STACK_SWITCH_FRAME_SIZE)
> + if (validate_sp_size(sp, tsk,
> STACK_SWITCH_FRAME_SIZE)
> && stack[STACK_INT_FRAME_MARKER_LONGS] ==
> STACK_FRAME_REGS_MARKER) {
> struct pt_regs *regs = (struct pt_regs *)
> (sp + STACK_INT_FRAME_REGS);
> diff --git a/arch/powerpc/kernel/stacktrace.c
> b/arch/powerpc/kernel/stacktrace.c
> index 453ac317a6cf..1dbbf30f265e 100644
> --- a/arch/powerpc/kernel/stacktrace.c
> +++ b/arch/powerpc/kernel/stacktrace.c
> @@ -43,7 +43,7 @@ void __no_sanitize_address
> arch_stack_walk(stack_trace_consume_fn consume_entry,
> unsigned long *stack = (unsigned long *) sp;
> unsigned long newsp, ip;
>
> - if (!validate_sp(sp, task, STACK_FRAME_OVERHEAD))
> + if (!validate_sp(sp, task))
> return;
>
> newsp = stack[0];
> diff --git a/arch/powerpc/perf/callchain.c
> b/arch/powerpc/perf/callchain.c
> index b01497ed5173..6b4434dd0ff3 100644
> --- a/arch/powerpc/perf/callchain.c
> +++ b/arch/powerpc/perf/callchain.c
> @@ -27,7 +27,7 @@ static int valid_next_sp(unsigned long sp, unsigned
> long prev_sp)
> {
> if (sp & 0xf)
> return 0; /* must be 16-byte aligned */
> - if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
> + if (!validate_sp(sp, current))
> return 0;
> if (sp >= prev_sp + STACK_FRAME_MIN_SIZE)
> return 1;
> @@ -53,7 +53,7 @@ perf_callchain_kernel(struct
> perf_callchain_entry_ctx *entry, struct pt_regs *re
> sp = regs->gpr[1];
> perf_callchain_store(entry, perf_instruction_pointer(regs));
>
> - if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
> + if (!validate_sp(sp, current))
> return;
>
> for (;;) {
> @@ -61,7 +61,7 @@ perf_callchain_kernel(struct
> perf_callchain_entry_ctx *entry, struct pt_regs *re
> next_sp = fp[0];
>
> if (next_sp == sp + STACK_INT_FRAME_SIZE &&
> - validate_sp(sp, current, STACK_INT_FRAME_SIZE) &&
> + validate_sp_size(sp, current,
> STACK_INT_FRAME_SIZE) &&
> fp[STACK_INT_FRAME_MARKER_LONGS] ==
> STACK_FRAME_REGS_MARKER) {
> /*
> * This looks like an interrupt frame for an
