[PATCH v2 1/9] arm64: allow kprobes on EL0 handlers

Mark Rutland
2022-10-19T15:00:16Z

Currently do_sysinstr() and do_cp15instr() are marked with
NOKPROBE_SYMBOL(). However, these are only called for exceptions taken
from EL0, and there is no risk of recursion in kprobes, so this is not
necessary.

Remove the NOKPROBE_SYMBOL() annotation, and rename the two functions to
more clearly indicate that these are solely for exceptions taken from
EL0, better matching the names used by the lower level entry points in
entry-common.c.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
---
arch/arm64/include/asm/exception.h | 4 ++--
arch/arm64/kernel/entry-common.c | 4 ++--
arch/arm64/kernel/traps.c | 6 ++----
3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h
index 19713d0f013b..bc0dd002106d 100644
--- a/arch/arm64/include/asm/exception.h
+++ b/arch/arm64/include/asm/exception.h
@@ -67,10 +67,10 @@ void do_fpsimd_acc(unsigned long esr, struct pt_regs *regs);
void do_sve_acc(unsigned long esr, struct pt_regs *regs);
void do_sme_acc(unsigned long esr, struct pt_regs *regs);
void do_fpsimd_exc(unsigned long esr, struct pt_regs *regs);
-void do_sysinstr(unsigned long esr, struct pt_regs *regs);
+void do_el0_sys(unsigned long esr, struct pt_regs *regs);
void do_sp_pc_abort(unsigned long addr, unsigned long esr, struct pt_regs *regs);
void bad_el0_sync(struct pt_regs *regs, int reason, unsigned long esr);
-void do_cp15instr(unsigned long esr, struct pt_regs *regs);
+void do_el0_cp15(unsigned long esr, struct pt_regs *regs);
int do_compat_alignment_fixup(unsigned long addr, struct pt_regs *regs);
void do_el0_svc(struct pt_regs *regs);
void do_el0_svc_compat(struct pt_regs *regs);
diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index 9173fad279af..135d4a5868fe 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -569,7 +569,7 @@ static void noinstr el0_sys(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
- do_sysinstr(esr, regs);
+ do_el0_sys(esr, regs);
exit_to_user_mode(regs);
}

@@ -761,7 +761,7 @@ static void noinstr el0_cp15(struct pt_regs *regs, unsigned long esr)
{
enter_from_user_mode(regs);
local_daif_restore(DAIF_PROCCTX);
- do_cp15instr(esr, regs);
+ do_el0_cp15(esr, regs);
exit_to_user_mode(regs);
}

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 23d281ed7621..ae184d661067 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -748,7 +748,7 @@ static const struct sys64_hook cp15_64_hooks[] = {
{},
};

-void do_cp15instr(unsigned long esr, struct pt_regs *regs)
+void do_el0_cp15(unsigned long esr, struct pt_regs *regs)
{
const struct sys64_hook *hook, *hook_base;

@@ -786,10 +786,9 @@ void do_cp15instr(unsigned long esr, struct pt_regs *regs)
*/
do_undefinstr(regs, esr);
}
-NOKPROBE_SYMBOL(do_cp15instr);
#endif

-void do_sysinstr(unsigned long esr, struct pt_regs *regs)
+void do_el0_sys(unsigned long esr, struct pt_regs *regs)
{
const struct sys64_hook *hook;

@@ -806,7 +805,6 @@ void do_sysinstr(unsigned long esr, struct pt_regs *regs)
*/
do_undefinstr(regs, esr);
}
-NOKPROBE_SYMBOL(do_sysinstr);

static const char *esr_class_str[] = {
[0 ... ESR_ELx_EC_MAX] = "UNRECOGNIZED EC",