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| author | Mark Rutland <mark.rutland@arm.com> | 2020-12-02 14:15:55 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2020-12-02 20:49:11 +0100 |
| commit | 3d2403fd10a1dbb359b154af41ffed9f2a7520e8 (patch) | |
| tree | 9b9a9ec4d627c49ebb3c1231481a6f86dd1bf1f7 /arch/arm64/kernel/entry.S | |
| parent | arm64: uaccess cleanup macro naming (diff) | |
| download | linux-3d2403fd10a1dbb359b154af41ffed9f2a7520e8.tar.xz linux-3d2403fd10a1dbb359b154af41ffed9f2a7520e8.zip | |
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/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 19 |
1 files changed, 3 insertions, 16 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index b295fb912b12..bdd3b57b12f5 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -216,12 +216,6 @@ alternative_else_nop_endif .else add x21, sp, #S_FRAME_SIZE get_current_task tsk - /* Save the task's original addr_limit and set USER_DS */ - ldr x20, [tsk, #TSK_TI_ADDR_LIMIT] - str x20, [sp, #S_ORIG_ADDR_LIMIT] - mov x20, #USER_DS - str x20, [tsk, #TSK_TI_ADDR_LIMIT] - /* No need to reset PSTATE.UAO, hardware's already set it to 0 for us */ .endif /* \el == 0 */ mrs x22, elr_el1 mrs x23, spsr_el1 @@ -279,12 +273,6 @@ alternative_else_nop_endif .macro kernel_exit, el .if \el != 0 disable_daif - - /* Restore the task's original addr_limit. */ - ldr x20, [sp, #S_ORIG_ADDR_LIMIT] - str x20, [tsk, #TSK_TI_ADDR_LIMIT] - - /* No need to restore UAO, it will be restored from SPSR_EL1 */ .endif /* Restore pmr */ @@ -999,10 +987,9 @@ SYM_CODE_START(__sdei_asm_entry_trampoline) mov x4, xzr /* - * Use reg->interrupted_regs.addr_limit to remember whether to unmap - * the kernel on exit. + * Remember whether to unmap the kernel on exit. */ -1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] +1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)] #ifdef CONFIG_RANDOMIZE_BASE adr x4, tramp_vectors + PAGE_SIZE @@ -1023,7 +1010,7 @@ NOKPROBE(__sdei_asm_entry_trampoline) * x4: struct sdei_registered_event argument from registration time. */ SYM_CODE_START(__sdei_asm_exit_trampoline) - ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_ORIG_ADDR_LIMIT)] + ldr x4, [x4, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)] cbnz x4, 1f tramp_unmap_kernel tmp=x4 |