Commit d60b228f authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon
Browse files

arm64: entry: split SDEI entry 



We'd like to keep all the entry sequencing in entry-common.c, as this
will allow us to ensure this is consistent, and free from any unsound
instrumentation.

Currently __sdei_handler() performs the NMI entry/exit sequences in
sdei.c. Let's split the low-level entry sequence from the event
handling, moving the former to entry-common.c and keeping the latter in
sdei.c. The event handling function is renamed to do_sdei_event(),
matching the do_${FOO}() pattern used for other exception handlers.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Acked-by: default avatarMarc Zyngier <maz@kernel.org>
Reviewed-by: default avatarJoey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210607094624.34689-18-mark.rutland@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 8168f098

arch/arm64/include/asm/sdei.h

+3 −0
Original line number Diff line number Diff line
@@ -37,6 +37,9 @@ struct sdei_registered_event; 
asmlinkage unsigned long __sdei_handler(struct pt_regs *regs,

					struct sdei_registered_event *arg);



unsigned long do_sdei_event(struct pt_regs *regs,

			    struct sdei_registered_event *arg);



unsigned long sdei_arch_get_entry_point(int conduit);

#define sdei_arch_get_entry_point(x)	sdei_arch_get_entry_point(x)

arch/arm64/kernel/entry-common.c

+37 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <asm/kprobes.h>

#include <asm/mmu.h>

#include <asm/processor.h>

#include <asm/sdei.h>

#include <asm/stacktrace.h>

#include <asm/sysreg.h>

#include <asm/system_misc.h>
@@ -710,3 +711,39 @@ asmlinkage void noinstr handle_bad_stack(struct pt_regs *regs) 
	panic_bad_stack(regs, esr, far);

}

#endif /* CONFIG_VMAP_STACK */



#ifdef CONFIG_ARM_SDE_INTERFACE

asmlinkage noinstr unsigned long

__sdei_handler(struct pt_regs *regs, struct sdei_registered_event *arg)

{

	unsigned long ret;



	/*

	 * We didn't take an exception to get here, so the HW hasn't

	 * set/cleared bits in PSTATE that we may rely on.

	 *

	 * The original SDEI spec (ARM DEN 0054A) can be read ambiguously as to

	 * whether PSTATE bits are inherited unchanged or generated from

	 * scratch, and the TF-A implementation always clears PAN and always

	 * clears UAO. There are no other known implementations.

	 *

	 * Subsequent revisions (ARM DEN 0054B) follow the usual rules for how

	 * PSTATE is modified upon architectural exceptions, and so PAN is

	 * either inherited or set per SCTLR_ELx.SPAN, and UAO is always

	 * cleared.

	 *

	 * We must explicitly reset PAN to the expected state, including

	 * clearing it when the host isn't using it, in case a VM had it set.

	 */

	if (system_uses_hw_pan())

		set_pstate_pan(1);

	else if (cpu_has_pan())

		set_pstate_pan(0);



	arm64_enter_nmi(regs);

	ret = do_sdei_event(regs, arg);

	arm64_exit_nmi(regs);



	return ret;

}

#endif /* CONFIG_ARM_SDE_INTERFACE */

arch/arm64/kernel/sdei.c

+3 −45
Original line number Diff line number Diff line
@@ -231,12 +231,12 @@ unsigned long sdei_arch_get_entry_point(int conduit) 
}



/*

 * __sdei_handler() returns one of:

 * do_sdei_event() returns one of:

 *  SDEI_EV_HANDLED -  success, return to the interrupted context.

 *  SDEI_EV_FAILED  -  failure, return this error code to firmare.

 *  virtual-address -  success, return to this address.

 */

static __kprobes unsigned long _sdei_handler(struct pt_regs *regs,

unsigned long __kprobes do_sdei_event(struct pt_regs *regs,

				      struct sdei_registered_event *arg)

{

	u32 mode;
@@ -292,45 +292,3 @@ static __kprobes unsigned long _sdei_handler(struct pt_regs *regs, 


	return vbar + 0x480;

}
 


static void __kprobes notrace __sdei_pstate_entry(void)

{

	/*

	 * The original SDEI spec (ARM DEN 0054A) can be read ambiguously as to

	 * whether PSTATE bits are inherited unchanged or generated from

	 * scratch, and the TF-A implementation always clears PAN and always

	 * clears UAO. There are no other known implementations.

	 *

	 * Subsequent revisions (ARM DEN 0054B) follow the usual rules for how

	 * PSTATE is modified upon architectural exceptions, and so PAN is

	 * either inherited or set per SCTLR_ELx.SPAN, and UAO is always

	 * cleared.

	 *

	 * We must explicitly reset PAN to the expected state, including

	 * clearing it when the host isn't using it, in case a VM had it set.

	 */

	if (system_uses_hw_pan())

		set_pstate_pan(1);

	else if (cpu_has_pan())

		set_pstate_pan(0);

}



asmlinkage noinstr unsigned long

__sdei_handler(struct pt_regs *regs, struct sdei_registered_event *arg)

{

	unsigned long ret;



	/*

	 * 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.

	 */

	__sdei_pstate_entry();



	arm64_enter_nmi(regs);



	ret = _sdei_handler(regs, arg);



	arm64_exit_nmi(regs);



	return ret;

}