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SubjectRe: [PATCH v4 19/23] x86/ftrace: Use vmalloc special flag
On Mon, 22 Apr 2019 11:58:01 -0700
Rick Edgecombe <rick.p.edgecombe@intel.com> wrote:

> Use new flag VM_FLUSH_RESET_PERMS for handling freeing of special
> permissioned memory in vmalloc and remove places where memory was set NX
> and RW before freeing which is no longer needed.
>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>

Tested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Steven Rostedt (VMware) <rostedt@godomis.org>

-- Steve

> ---
> arch/x86/kernel/ftrace.c | 14 ++++++--------
> 1 file changed, 6 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index 53ba1aa3a01f..0caf8122d680 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -678,12 +678,8 @@ static inline void *alloc_tramp(unsigned long size)
> {
> return module_alloc(size);
> }
> -static inline void tramp_free(void *tramp, int size)
> +static inline void tramp_free(void *tramp)
> {
> - int npages = PAGE_ALIGN(size) >> PAGE_SHIFT;
> -
> - set_memory_nx((unsigned long)tramp, npages);
> - set_memory_rw((unsigned long)tramp, npages);
> module_memfree(tramp);
> }
> #else
> @@ -692,7 +688,7 @@ static inline void *alloc_tramp(unsigned long size)
> {
> return NULL;
> }
> -static inline void tramp_free(void *tramp, int size) { }
> +static inline void tramp_free(void *tramp) { }
> #endif
>
> /* Defined as markers to the end of the ftrace default trampolines */
> @@ -808,6 +804,8 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
> /* ALLOC_TRAMP flags lets us know we created it */
> ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
>
> + set_vm_flush_reset_perms(trampoline);
> +
> /*
> * Module allocation needs to be completed by making the page
> * executable. The page is still writable, which is a security hazard,
> @@ -816,7 +814,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
> set_memory_x((unsigned long)trampoline, npages);
> return (unsigned long)trampoline;
> fail:
> - tramp_free(trampoline, *tramp_size);
> + tramp_free(trampoline);
> return 0;
> }
>
> @@ -947,7 +945,7 @@ void arch_ftrace_trampoline_free(struct ftrace_ops *ops)
> if (!ops || !(ops->flags & FTRACE_OPS_FL_ALLOC_TRAMP))
> return;
>
> - tramp_free((void *)ops->trampoline, ops->trampoline_size);
> + tramp_free((void *)ops->trampoline);
> ops->trampoline = 0;
> }
>

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