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It was mistaken that the physical memory returned from "reserve_mem" had to
be vmap()'d to get to it from a virtual address. But reserve_mem already
maps the memory to the virtual address of the kernel so a simple
phys_to_virt() can be used to get to the virtual address from the physical
memory returned by "reserve_mem". With this new found knowledge, the
code can be cleaned up and simplified.
- Enforce that the persistent memory is page aligned
As the buffers using the persistent memory are all going to be
mapped via pages, make sure that the memory given to the tracing
infrastructure is page aligned. If it is not, it will print a warning
and fail to map the buffer.
- Use phys_to_virt() to get the virtual address from reserve_mem
Instead of calling vmap() on the physical memory returned from
"reserve_mem", use phys_to_virt() instead.
As the memory returned by "memmap" or any other means where a physical
address is given to the tracing infrastructure, it still needs to
be vmap(). Since this memory can never be returned back to the buddy
allocator nor should it ever be memmory mapped to user space, flag
this buffer and up the ref count. The ref count will keep it from
ever being freed, and the flag will prevent it from ever being memory
mapped to user space.
- Use vmap_page_range() for memmap virtual address mapping
For the memmap buffer, instead of allocating an array of struct pages,
assigning them to the contiguous phsycial memory and then passing that to
vmap(), use vmap_page_range() instead
- Replace flush_dcache_folio() with flush_kernel_vmap_range()
Instead of calling virt_to_folio() and passing that to
flush_dcache_folio(), just call flush_kernel_vmap_range() directly.
This also fixes a bug where if a subbuffer was bigger than PAGE_SIZE
only the PAGE_SIZE portion would be flushed.
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Merge tag 'trace-ringbuffer-v6.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace
Pull ring-buffer updates from Steven Rostedt:
"Persistent buffer cleanups and simplifications.
It was mistaken that the physical memory returned from "reserve_mem"
had to be vmap()'d to get to it from a virtual address. But
reserve_mem already maps the memory to the virtual address of the
kernel so a simple phys_to_virt() can be used to get to the virtual
address from the physical memory returned by "reserve_mem". With this
new found knowledge, the code can be cleaned up and simplified.
- Enforce that the persistent memory is page aligned
As the buffers using the persistent memory are all going to be
mapped via pages, make sure that the memory given to the tracing
infrastructure is page aligned. If it is not, it will print a
warning and fail to map the buffer.
- Use phys_to_virt() to get the virtual address from reserve_mem
Instead of calling vmap() on the physical memory returned from
"reserve_mem", use phys_to_virt() instead.
As the memory returned by "memmap" or any other means where a
physical address is given to the tracing infrastructure, it still
needs to be vmap(). Since this memory can never be returned back to
the buddy allocator nor should it ever be memmory mapped to user
space, flag this buffer and up the ref count. The ref count will
keep it from ever being freed, and the flag will prevent it from
ever being memory mapped to user space.
- Use vmap_page_range() for memmap virtual address mapping
For the memmap buffer, instead of allocating an array of struct
pages, assigning them to the contiguous phsycial memory and then
passing that to vmap(), use vmap_page_range() instead
- Replace flush_dcache_folio() with flush_kernel_vmap_range()
Instead of calling virt_to_folio() and passing that to
flush_dcache_folio(), just call flush_kernel_vmap_range() directly.
This also fixes a bug where if a subbuffer was bigger than
PAGE_SIZE only the PAGE_SIZE portion would be flushed"
* tag 'trace-ringbuffer-v6.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ring-buffer: Use flush_kernel_vmap_range() over flush_dcache_folio()
tracing: Use vmap_page_range() to map memmap ring buffer
tracing: Have reserve_mem use phys_to_virt() and separate from memmap buffer
tracing: Enforce the persistent ring buffer to be page aligned