diff options
author | Mark Rutland <mark.rutland@arm.com> | 2020-12-02 13:15:55 +0000 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2020-12-02 19:49:11 +0000 |
commit | 3d2403fd10a1dbb359b154af41ffed9f2a7520e8 (patch) | |
tree | 9b9a9ec4d627c49ebb3c1231481a6f86dd1bf1f7 /arch/arm64/kernel/sdei.c | |
parent | 7b90dc40e36e0beb0fdecfef80f33a2e88aced14 (diff) |
arm64: uaccess: remove set_fs()
Now that the uaccess primitives dont take addr_limit into account, we
have no need to manipulate this via set_fs() and get_fs(). Remove
support for these, along with some infrastructure this renders
redundant.
We no longer need to flip UAO to access kernel memory under KERNEL_DS,
and head.S unconditionally clears UAO for all kernel configurations via
an ERET in init_kernel_el. Thus, we don't need to dynamically flip UAO,
nor do we need to context-switch it. However, we still need to adjust
PAN during SDEI entry.
Masking of __user pointers no longer needs to use the dynamic value of
addr_limit, and can use a constant derived from the maximum possible
userspace task size. A new TASK_SIZE_MAX constant is introduced for
this, which is also used by core code. In configurations supporting
52-bit VAs, this may include a region of unusable VA space above a
48-bit TTBR0 limit, but never includes any portion of TTBR1.
Note that TASK_SIZE_MAX is an exclusive limit, while USER_DS and
KERNEL_DS were inclusive limits, and is converted to a mask by
subtracting one.
As the SDEI entry code repurposes the otherwise unnecessary
pt_regs::orig_addr_limit field to store the TTBR1 of the interrupted
context, for now we rename that to pt_regs::sdei_ttbr1. In future we can
consider factoring that out.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: James Morse <james.morse@arm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201202131558.39270-10-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/sdei.c')
-rw-r--r-- | arch/arm64/kernel/sdei.c | 7 |
1 files changed, 1 insertions, 6 deletions
diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c index c9640e50967a..e04b3e90c003 100644 --- a/arch/arm64/kernel/sdei.c +++ b/arch/arm64/kernel/sdei.c @@ -242,15 +242,12 @@ asmlinkage __kprobes notrace unsigned long __sdei_handler(struct pt_regs *regs, struct sdei_registered_event *arg) { unsigned long ret; - mm_segment_t orig_addr_limit; /* * We didn't take an exception to get here, so the HW hasn't - * set/cleared bits in PSTATE that we may rely on. Initialize PAN, then - * use force_uaccess_begin() to reset addr_limit. + * set/cleared bits in PSTATE that we may rely on. Initialize PAN. */ __sdei_pstate_entry(); - orig_addr_limit = force_uaccess_begin(); nmi_enter(); @@ -258,7 +255,5 @@ __sdei_handler(struct pt_regs *regs, struct sdei_registered_event *arg) nmi_exit(); - force_uaccess_end(orig_addr_limit); - return ret; } |