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| author | Thomas Gleixner <tglx@linutronix.de> | 2021-10-21 15:55:08 -0700 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2021-10-26 10:18:09 +0200 |
| commit | 6f6a7c09c4065a5b140194dfcfe4cf7104fec4d2 (patch) | |
| tree | 58a2932ed1920d7d74a48af3fa700afcadb06382 /arch/x86/kernel/fpu/core.c | |
| parent | 84e4dccc8fce20b497388d756e12de5c9006eb48 (diff) | |
| download | linux-6f6a7c09c4065a5b140194dfcfe4cf7104fec4d2.tar.gz | |
x86/fpu: Add members to struct fpu to cache permission information
Dynamically enabled features can be requested by any thread of a running
process at any time. The request does neither enable the feature nor
allocate larger buffers. It just stores the permission to use the feature
by adding the features to the permission bitmap and by calculating the
required sizes for kernel and user space.
The reallocation of the kernel buffer happens when the feature is used
for the first time which is caught by an exception. The permission
bitmap is then checked and if the feature is permitted, then it becomes
fully enabled. If not, the task dies similarly to a task which uses an
undefined instruction.
The size information is precomputed to allow proper sigaltstack size checks
once the feature is permitted, but not yet in use because otherwise this
would open race windows where too small stacks could be installed causing
a later fail on signal delivery.
Initialize them to the default feature set and sizes.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211021225527.10184-5-chang.seok.bae@intel.com
Diffstat (limited to 'arch/x86/kernel/fpu/core.c')
| -rw-r--r-- | arch/x86/kernel/fpu/core.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 9c475e2efd4d..b05f6a3b2057 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -412,6 +412,11 @@ void fpstate_reset(struct fpu *fpu) /* Set the fpstate pointer to the default fpstate */ fpu->fpstate = &fpu->__fpstate; __fpstate_reset(fpu->fpstate); + + /* Initialize the permission related info in fpu */ + fpu->perm.__state_perm = fpu_kernel_cfg.default_features; + fpu->perm.__state_size = fpu_kernel_cfg.default_size; + fpu->perm.__user_state_size = fpu_user_cfg.default_size; } /* Clone current's FPU state on fork */ |