@@ -902,13 +902,14 @@ el0_dbg:
* Debug exception handling
*/
tbnz x24, #0, el0_inv // EL0 only
+ mrs x24, far_el1
gic_prio_kentry_setup tmp=x3
- mrs x0, far_el1
+ ct_user_exit
+ mov x0, x24
mov x1, x25
mov x2, sp
bl do_debug_exception
enable_da_f
- ct_user_exit
b ret_to_user
el0_inv:
enable_daif
@@ -958,13 +959,14 @@ ENDPROC(el1_error)
el0_error:
kernel_entry 0
el0_error_naked:
- mrs x1, esr_el1
+ mrs x25, esr_el1
gic_prio_kentry_setup tmp=x2
+ ct_user_exit
enable_dbg
mov x0, sp
+ mov x1, x25
bl do_serror
enable_da_f
- ct_user_exit
b ret_to_user
ENDPROC(el0_error)
When taking an SError or Debug exception from EL0, we run the C handler for these exceptions before updating the context tracking code and unmasking lower priority interrupts. When booting with nohz_full lockdep tells us we got this wrong: | ============================= | WARNING: suspicious RCU usage | 5.3.0-rc2-00010-gb4b5e9dcb11b-dirty #11271 Not tainted | ----------------------------- | include/linux/rcupdate.h:643 rcu_read_unlock() used illegally wh! | | other info that might help us debug this: | | | RCU used illegally from idle CPU! | rcu_scheduler_active = 2, debug_locks = 1 | RCU used illegally from extended quiescent state! | 1 lock held by a.out/432: | #0: 00000000c7a79515 (rcu_read_lock){....}, at: brk_handler+0x00 | | stack backtrace: | CPU: 1 PID: 432 Comm: a.out Not tainted 5.3.0-rc2-00010-gb4b5e9d1 | Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno De8 | Call trace: | dump_backtrace+0x0/0x140 | show_stack+0x14/0x20 | dump_stack+0xbc/0x104 | lockdep_rcu_suspicious+0xf8/0x108 | brk_handler+0x164/0x1b0 | do_debug_exception+0x11c/0x278 | el0_dbg+0x14/0x20 Move the ct_user_exit calls to be before do_debug_exception() and do_serror() respectively. Cc: Masami Hiramatsu <mhiramat@kernel.org> Fixes: 6c81fe7925cc4c42 ("arm64: enable context tracking") Signed-off-by: James Morse <james.morse@arm.com> --- The context to this is Masami Hiramatsu's patch adding sanity checks for this: Link: https://lore.kernel.org/r/156466954920.8995.14798868044005509434.stgit@devnote2 --- arch/arm64/kernel/entry.S | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)