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author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2023-03-12 14:26:03 +0300 |
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committer | Dave Hansen <dave.hansen@linux.intel.com> | 2023-03-16 13:08:39 -0700 |
commit | 2f8794bd087e7958c8d1f0a0538856ca03e0bf3c (patch) | |
tree | fb0d64dff58561c2b5f71f6ebfe30aa0bd6b41b7 /arch/x86/kernel/process_64.c | |
parent | e0bddc19ba9578bc4e4c60a3f29ccc227277854c (diff) | |
download | linux-stable-2f8794bd087e7958c8d1f0a0538856ca03e0bf3c.tar.gz linux-stable-2f8794bd087e7958c8d1f0a0538856ca03e0bf3c.tar.bz2 linux-stable-2f8794bd087e7958c8d1f0a0538856ca03e0bf3c.zip |
x86/mm: Provide arch_prctl() interface for LAM
Add a few of arch_prctl() handles:
- ARCH_ENABLE_TAGGED_ADDR enabled LAM. The argument is required number
of tag bits. It is rounded up to the nearest LAM mode that can
provide it. For now only LAM_U57 is supported, with 6 tag bits.
- ARCH_GET_UNTAG_MASK returns untag mask. It can indicates where tag
bits located in the address.
- ARCH_GET_MAX_TAG_BITS returns the maximum tag bits user can request.
Zero if LAM is not supported.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Alexander Potapenko <glider@google.com>
Link: https://lore.kernel.org/all/20230312112612.31869-9-kirill.shutemov%40linux.intel.com
Diffstat (limited to 'arch/x86/kernel/process_64.c')
-rw-r--r-- | arch/x86/kernel/process_64.c | 55 |
1 files changed, 54 insertions, 1 deletions
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index cd34bcf7f860..186f34add865 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -743,6 +743,48 @@ static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr) } #endif +#ifdef CONFIG_ADDRESS_MASKING + +#define LAM_U57_BITS 6 + +static int prctl_enable_tagged_addr(struct mm_struct *mm, unsigned long nr_bits) +{ + if (!cpu_feature_enabled(X86_FEATURE_LAM)) + return -ENODEV; + + /* PTRACE_ARCH_PRCTL */ + if (current->mm != mm) + return -EINVAL; + + if (mmap_write_lock_killable(mm)) + return -EINTR; + + if (test_bit(MM_CONTEXT_LOCK_LAM, &mm->context.flags)) { + mmap_write_unlock(mm); + return -EBUSY; + } + + if (!nr_bits) { + mmap_write_unlock(mm); + return -EINVAL; + } else if (nr_bits <= LAM_U57_BITS) { + mm->context.lam_cr3_mask = X86_CR3_LAM_U57; + mm->context.untag_mask = ~GENMASK(62, 57); + } else { + mmap_write_unlock(mm); + return -EINVAL; + } + + write_cr3(__read_cr3() | mm->context.lam_cr3_mask); + set_tlbstate_lam_mode(mm); + set_bit(MM_CONTEXT_LOCK_LAM, &mm->context.flags); + + mmap_write_unlock(mm); + + return 0; +} +#endif + long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) { int ret = 0; @@ -830,7 +872,18 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) case ARCH_MAP_VDSO_64: return prctl_map_vdso(&vdso_image_64, arg2); #endif - +#ifdef CONFIG_ADDRESS_MASKING + case ARCH_GET_UNTAG_MASK: + return put_user(task->mm->context.untag_mask, + (unsigned long __user *)arg2); + case ARCH_ENABLE_TAGGED_ADDR: + return prctl_enable_tagged_addr(task->mm, arg2); + case ARCH_GET_MAX_TAG_BITS: + if (!cpu_feature_enabled(X86_FEATURE_LAM)) + return put_user(0, (unsigned long __user *)arg2); + else + return put_user(LAM_U57_BITS, (unsigned long __user *)arg2); +#endif default: ret = -EINVAL; break; |