Commit a0ccf2ba authored by Mark Rutland's avatar Mark Rutland Committed by Catalin Marinas
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arm64: sdei: move uaccess logic to arch/arm64/ 



The SDEI support code is split across arch/arm64/ and drivers/firmware/,
largley this is split so that the arch-specific portions are under
arch/arm64, and the management logic is under drivers/firmware/.
However, exception entry fixups are currently under drivers/firmware.

Let's move the exception entry fixups under arch/arm64/. This
de-clutters the management logic, and puts all the arch-specific
portions in one place. Doing this also allows the fixups to be applied
earlier, so things like PAN and UAO will be in a known good state before
we run other logic. This will also make subsequent refactoring easier.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarJames Morse <james.morse@arm.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201202131558.39270-2-mark.rutland@arm.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent d87a8e65

arch/arm64/kernel/sdei.c

+12 −6
Original line number Diff line number Diff line
@@ -178,12 +178,6 @@ static __kprobes unsigned long _sdei_handler(struct pt_regs *regs, 
		sdei_api_event_context(i, &regs->regs[i]);

	}



	/*

	 * We didn't take an exception to get here, set PAN. UAO will be cleared

	 * by sdei_event_handler()s force_uaccess_begin() call.

	 */

	__uaccess_enable_hw_pan();



	err = sdei_event_handler(regs, arg);

	if (err)

		return SDEI_EV_FAILED;
@@ -227,6 +221,16 @@ 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 PAN or

	 * cleared UAO, and the exception entry code hasn't reset addr_limit.

	 * Set PAN, then use force_uaccess_begin() to clear UAO and reset

	 * addr_limit.

	 */

	__uaccess_enable_hw_pan();

	orig_addr_limit = force_uaccess_begin();



	nmi_enter();
@@ -234,5 +238,7 @@ __sdei_handler(struct pt_regs *regs, struct sdei_registered_event *arg) 


	nmi_exit();



	force_uaccess_end(orig_addr_limit);



	return ret;

}

drivers/firmware/arm_sdei.c

+0 −14
Original line number Diff line number Diff line
@@ -31,7 +31,6 @@ 
#include <linux/slab.h>

#include <linux/smp.h>

#include <linux/spinlock.h>

#include <linux/uaccess.h>



/*

 * The call to use to reach the firmware.
@@ -1092,26 +1091,13 @@ int sdei_event_handler(struct pt_regs *regs, 
		       struct sdei_registered_event *arg)

{

	int err;

	mm_segment_t orig_addr_limit;

	u32 event_num = arg->event_num;



	/*

	 * Save restore 'fs'.

	 * The architecture's entry code save/restores 'fs' when taking an

	 * exception from the kernel. This ensures addr_limit isn't inherited

	 * if you interrupted something that allowed the uaccess routines to

	 * access kernel memory.

	 * Do the same here because this doesn't come via the same entry code.

	*/

	orig_addr_limit = force_uaccess_begin();



	err = arg->callback(event_num, regs, arg->callback_arg);

	if (err)

		pr_err_ratelimited("event %u on CPU %u failed with error: %d\n",

				   event_num, smp_processor_id(), err);



	force_uaccess_end(orig_addr_limit);



	return err;

}

NOKPROBE_SYMBOL(sdei_event_handler);

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