Re: [PATCH mm-unstable v2 05/16] mm: arc: Use generic_mmap_hint()
From: Liam R. Howlett <hidden>
Date: 2024-12-12 21:15:20
Also in:
linux-alpha, linux-arm-kernel, linux-mips, linux-mm, linux-s390, linux-sh, lkml, loongarch, sparclinux
* Kalesh Singh [off-list ref] [241211 18:28]:
Introduce arc arch_mmap_hint() and define HAVE_ARCH_MMAP_HINT. This is a preparatory patch, no functional change is introduced.
You have changed the order of the map fixed check and the len check. I *think* what you have done is correct, but your comment is certainly wrong. Your generic call also has more checks than exist in this version of the code - which, again is probably good, but a functional change surely?
quoted hunk ↗ jump to hunk
Signed-off-by: Kalesh Singh <redacted> --- Changes in v2: - MAP_FIXED case is also handled in arch_mmap_hint() since this is just a special case of the hint addr being "enforced", per Yang Shi. - Consolidate error handling in arch_mmap_hint(). arch/arc/include/asm/pgtable.h | 1 + arch/arc/mm/mmap.c | 43 +++++++++++++++++----------------- 2 files changed, 23 insertions(+), 21 deletions(-)diff --git a/arch/arc/include/asm/pgtable.h b/arch/arc/include/asm/pgtable.h index 4cf45a99fd79..af3210ea4888 100644 --- a/arch/arc/include/asm/pgtable.h +++ b/arch/arc/include/asm/pgtable.h@@ -28,6 +28,7 @@ extern pgd_t swapper_pg_dir[] __aligned(PAGE_SIZE); /* to cope with aliasing VIPT cache */ #define HAVE_ARCH_UNMAPPED_AREA +#define HAVE_ARCH_MMAP_HINT #endif /* __ASSEMBLY__ */diff --git a/arch/arc/mm/mmap.c b/arch/arc/mm/mmap.c index 2185afe8d59f..df01d4d9964b 100644 --- a/arch/arc/mm/mmap.c +++ b/arch/arc/mm/mmap.c@@ -14,6 +14,26 @@ #include <asm/cacheflush.h> +unsigned long arch_mmap_hint(struct file *filp, unsigned long addr, + unsigned long len, unsigned long pgoff, + unsigned long flags) +{ + if (len > TASK_SIZE) + return -ENOMEM; + + /* + * We enforce the MAP_FIXED case. + */ + if (flags & MAP_FIXED) { + if (flags & MAP_SHARED && + (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)) + return -EINVAL; + return addr; + } + + return generic_mmap_hint(filp, addr, len, pgoff, flags); +} + /* * Ensure that shared mappings are correctly aligned to * avoid aliasing issues with VIPT caches.@@ -27,30 +47,11 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long flags, vm_flags_t vm_flags) { struct mm_struct *mm = current->mm; - struct vm_area_struct *vma; struct vm_unmapped_area_info info = {}; - /* - * We enforce the MAP_FIXED case. - */ - if (flags & MAP_FIXED) { - if (flags & MAP_SHARED && - (addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)) - return -EINVAL; + addr = arch_mmap_hint(filp, addr, len, pgoff, flags); + if (addr) return addr; - } - - if (len > TASK_SIZE) - return -ENOMEM; - - if (addr) { - addr = PAGE_ALIGN(addr); - - vma = find_vma(mm, addr); - if (TASK_SIZE - len >= addr && - (!vma || addr + len <= vm_start_gap(vma))) - return addr; - } info.length = len; info.low_limit = mm->mmap_base;-- 2.47.0.338.g60cca15819-goog