diff options
| author | Gabriel Krisman Bertazi <krisman@collabora.com> | 2020-10-03 23:25:28 -0400 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2020-10-26 13:46:46 +0100 |
| commit | 214f0e804358cdd13b5cbe4445189f23e30618b4 (patch) | |
| tree | 26375412b60264094acab4242858e156367f4deb /arch/x86 | |
| parent | 375d4bfda57392f0865dae051e1c4bd2700e8d71 (diff) | |
| download | lwn-214f0e804358cdd13b5cbe4445189f23e30618b4.tar.gz lwn-214f0e804358cdd13b5cbe4445189f23e30618b4.zip | |
x86/compat: Simplify compat syscall userspace allocation
When allocating user memory space for a compat system call, don't consider
whether the originating code is IA32 or X32, just allocate from a safe
region for both, beyond the redzone. This should be safe for IA32, and has
the benefit of avoiding TIF_IA32, which is about to be removed.
Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201004032536.1229030-3-krisman@collabora.com
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/compat.h | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h index 0e327a01f50f..f145e3326c6d 100644 --- a/arch/x86/include/asm/compat.h +++ b/arch/x86/include/asm/compat.h @@ -177,14 +177,13 @@ typedef struct user_regs_struct compat_elf_gregset_t; static inline void __user *arch_compat_alloc_user_space(long len) { - compat_uptr_t sp; - - if (test_thread_flag(TIF_IA32)) { - sp = task_pt_regs(current)->sp; - } else { - /* -128 for the x32 ABI redzone */ - sp = task_pt_regs(current)->sp - 128; - } + compat_uptr_t sp = task_pt_regs(current)->sp; + + /* + * -128 for the x32 ABI redzone. For IA32, it is not strictly + * necessary, but not harmful. + */ + sp -= 128; return (void __user *)round_down(sp - len, 16); } |