Add a function to remap an already mapped buffer with a new address in a decorated page-table: the already mapped buffer is unmapped, and a new mapping is added for the specified new address.
This is useful to track and remap a buffer which can be freed and then reallocated. Signed-off-by: Alexandre Chartre <[email protected]> --- arch/x86/include/asm/dpt.h | 1 + arch/x86/mm/dpt.c | 25 +++++++++++++++++++++++++ 2 files changed, 26 insertions(+) diff --git a/arch/x86/include/asm/dpt.h b/arch/x86/include/asm/dpt.h index fd8c1b84ffe2..3234ba968d80 100644 --- a/arch/x86/include/asm/dpt.h +++ b/arch/x86/include/asm/dpt.h @@ -57,6 +57,7 @@ extern int dpt_map_range(struct dpt *dpt, void *ptr, size_t size, enum page_table_level level); extern int dpt_map(struct dpt *dpt, void *ptr, unsigned long size); extern void dpt_unmap(struct dpt *dpt, void *ptr); +extern int dpt_remap(struct dpt *dpt, void **mapping, void *ptr, size_t size); static inline int dpt_map_module(struct dpt *dpt, char *module_name) { diff --git a/arch/x86/mm/dpt.c b/arch/x86/mm/dpt.c index adc59f9ed876..9517e3081716 100644 --- a/arch/x86/mm/dpt.c +++ b/arch/x86/mm/dpt.c @@ -809,6 +809,31 @@ int dpt_map_percpu(struct dpt *dpt, void *percpu_ptr, size_t size) } EXPORT_SYMBOL(dpt_map_percpu); +int dpt_remap(struct dpt *dpt, void **current_ptrp, void *new_ptr, size_t size) +{ + void *current_ptr = *current_ptrp; + int err; + + if (current_ptr == new_ptr) { + /* no change, already mapped */ + return 0; + } + + if (current_ptr) { + dpt_unmap(dpt, current_ptr); + *current_ptrp = NULL; + } + + err = dpt_map(dpt, new_ptr, size); + if (err) + return err; + + *current_ptrp = new_ptr; + + return 0; +} +EXPORT_SYMBOL(dpt_remap); + /* * dpt_create - allocate a page-table and create a corresponding * decorated page-table. The page-table is allocated and aligned -- 2.18.2
