| Message ID | 20200421141234.v2.5.I22067ad43e77ddfd4b64c2d49030628480f9e8d9@changeid (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kgdb: Support late serial drivers; enable early debug w/ boot consoles | expand |
On Tue, Apr 21, 2020 at 02:14:43PM -0700, Douglas Anderson wrote: > In order to make early kgdb work properly we need early_brk64() to be > able to call into it. This is as easy as adding a call into > call_break_hook() just like we do later in the normal brk_handler(). > > Once we do this we can let kgdb know that it can break into the > debugger a little earlier (specifically when parsing early_param's). > > NOTE: without this patch it turns out that arm64 can't do breakpoints > even at dbg_late_init(), so if we decide something about this patch is > wrong we might need to move dbg_late_init() a little later. > > Signed-off-by: Douglas Anderson <dianders@chromium.org> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Will Deacon <will@kernel.org> I haven't done any testing at this point (I'd hope to enable tests for this in the test suite), however FWIW and just so you know I didn't forget about this patch: Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Daniel.
diff --git a/arch/arm64/include/asm/debug-monitors.h b/arch/arm64/include/asm/debug-monitors.h index 7619f473155f..2d82a0314d29 100644 --- a/arch/arm64/include/asm/debug-monitors.h +++ b/arch/arm64/include/asm/debug-monitors.h @@ -97,6 +97,8 @@ void unregister_user_break_hook(struct break_hook *hook); void register_kernel_break_hook(struct break_hook *hook); void unregister_kernel_break_hook(struct break_hook *hook); +int call_break_hook(struct pt_regs *regs, unsigned int esr); + u8 debug_monitors_arch(void); enum dbg_active_el { diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c index 48222a4760c2..59c353dfc8e9 100644 --- a/arch/arm64/kernel/debug-monitors.c +++ b/arch/arm64/kernel/debug-monitors.c @@ -297,7 +297,7 @@ void unregister_kernel_break_hook(struct break_hook *hook) unregister_debug_hook(&hook->node); } -static int call_break_hook(struct pt_regs *regs, unsigned int esr) +int call_break_hook(struct pt_regs *regs, unsigned int esr) { struct break_hook *hook; struct list_head *list; diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index 43119922341f..96a47af870bc 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -301,6 +301,11 @@ static struct notifier_block kgdb_notifier = { .priority = -INT_MAX, }; +extern bool kgdb_arch_can_debug_early(void) +{ + return true; +} + /* * kgdb_arch_init - Perform any architecture specific initialization. * This function will handle the initialization of any architecture diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index cf402be5c573..a8173f0c1774 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -1044,6 +1044,9 @@ int __init early_brk64(unsigned long addr, unsigned int esr, if ((comment & ~KASAN_BRK_MASK) == KASAN_BRK_IMM) return kasan_handler(regs, esr) != DBG_HOOK_HANDLED; #endif + if (call_break_hook(regs, esr) == DBG_HOOK_HANDLED) + return 0; + return bug_handler(regs, esr) != DBG_HOOK_HANDLED; }
In order to make early kgdb work properly we need early_brk64() to be able to call into it. This is as easy as adding a call into call_break_hook() just like we do later in the normal brk_handler(). Once we do this we can let kgdb know that it can break into the debugger a little earlier (specifically when parsing early_param's). NOTE: without this patch it turns out that arm64 can't do breakpoints even at dbg_late_init(), so if we decide something about this patch is wrong we might need to move dbg_late_init() a little later. Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> --- Changes in v2: None arch/arm64/include/asm/debug-monitors.h | 2 ++ arch/arm64/kernel/debug-monitors.c | 2 +- arch/arm64/kernel/kgdb.c | 5 +++++ arch/arm64/kernel/traps.c | 3 +++ 4 files changed, 11 insertions(+), 1 deletion(-)