| From bb2d40739b734e74f5bd0c1f31af170c676c8e76 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Sun, 10 May 2020 05:41:56 +0800 |
| Subject: arm64: kgdb: Fix single-step exception handling oops |
| |
| From: Wei Li <liwei391@huawei.com> |
| |
| [ Upstream commit 8523c006264df65aac7d77284cc69aac46a6f842 ] |
| |
| After entering kdb due to breakpoint, when we execute 'ss' or 'go' (will |
| delay installing breakpoints, do single-step first), it won't work |
| correctly, and it will enter kdb due to oops. |
| |
| It's because the reason gotten in kdb_stub() is not as expected, and it |
| seems that the ex_vector for single-step should be 0, like what arch |
| powerpc/sh/parisc has implemented. |
| |
| Before the patch: |
| Entering kdb (current=0xffff8000119e2dc0, pid 0) on processor 0 due to Keyboard Entry |
| [0]kdb> bp printk |
| Instruction(i) BP #0 at 0xffff8000101486cc (printk) |
| is enabled addr at ffff8000101486cc, hardtype=0 installed=0 |
| |
| [0]kdb> g |
| |
| / # echo h > /proc/sysrq-trigger |
| |
| Entering kdb (current=0xffff0000fa878040, pid 266) on processor 3 due to Breakpoint @ 0xffff8000101486cc |
| [3]kdb> ss |
| |
| Entering kdb (current=0xffff0000fa878040, pid 266) on processor 3 Oops: (null) |
| due to oops @ 0xffff800010082ab8 |
| CPU: 3 PID: 266 Comm: sh Not tainted 5.7.0-rc4-13839-gf0e5ad491718 #6 |
| Hardware name: linux,dummy-virt (DT) |
| pstate: 00000085 (nzcv daIf -PAN -UAO) |
| pc : el1_irq+0x78/0x180 |
| lr : __handle_sysrq+0x80/0x190 |
| sp : ffff800015003bf0 |
| x29: ffff800015003d20 x28: ffff0000fa878040 |
| x27: 0000000000000000 x26: ffff80001126b1f0 |
| x25: ffff800011b6a0d8 x24: 0000000000000000 |
| x23: 0000000080200005 x22: ffff8000101486cc |
| x21: ffff800015003d30 x20: 0000ffffffffffff |
| x19: ffff8000119f2000 x18: 0000000000000000 |
| x17: 0000000000000000 x16: 0000000000000000 |
| x15: 0000000000000000 x14: 0000000000000000 |
| x13: 0000000000000000 x12: 0000000000000000 |
| x11: 0000000000000000 x10: 0000000000000000 |
| x9 : 0000000000000000 x8 : ffff800015003e50 |
| x7 : 0000000000000002 x6 : 00000000380b9990 |
| x5 : ffff8000106e99e8 x4 : ffff0000fadd83c0 |
| x3 : 0000ffffffffffff x2 : ffff800011b6a0d8 |
| x1 : ffff800011b6a000 x0 : ffff80001130c9d8 |
| Call trace: |
| el1_irq+0x78/0x180 |
| printk+0x0/0x84 |
| write_sysrq_trigger+0xb0/0x118 |
| proc_reg_write+0xb4/0xe0 |
| __vfs_write+0x18/0x40 |
| vfs_write+0xb0/0x1b8 |
| ksys_write+0x64/0xf0 |
| __arm64_sys_write+0x14/0x20 |
| el0_svc_common.constprop.2+0xb0/0x168 |
| do_el0_svc+0x20/0x98 |
| el0_sync_handler+0xec/0x1a8 |
| el0_sync+0x140/0x180 |
| |
| [3]kdb> |
| |
| After the patch: |
| Entering kdb (current=0xffff8000119e2dc0, pid 0) on processor 0 due to Keyboard Entry |
| [0]kdb> bp printk |
| Instruction(i) BP #0 at 0xffff8000101486cc (printk) |
| is enabled addr at ffff8000101486cc, hardtype=0 installed=0 |
| |
| [0]kdb> g |
| |
| / # echo h > /proc/sysrq-trigger |
| |
| Entering kdb (current=0xffff0000fa852bc0, pid 268) on processor 0 due to Breakpoint @ 0xffff8000101486cc |
| [0]kdb> g |
| |
| Entering kdb (current=0xffff0000fa852bc0, pid 268) on processor 0 due to Breakpoint @ 0xffff8000101486cc |
| [0]kdb> ss |
| |
| Entering kdb (current=0xffff0000fa852bc0, pid 268) on processor 0 due to SS trap @ 0xffff800010082ab8 |
| [0]kdb> |
| |
| Fixes: 44679a4f142b ("arm64: KGDB: Add step debugging support") |
| Signed-off-by: Wei Li <liwei391@huawei.com> |
| Tested-by: Douglas Anderson <dianders@chromium.org> |
| Reviewed-by: Douglas Anderson <dianders@chromium.org> |
| Link: https://lore.kernel.org/r/20200509214159.19680-2-liwei391@huawei.com |
| Signed-off-by: Will Deacon <will@kernel.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| arch/arm64/kernel/kgdb.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c |
| index 43119922341f8..1a157ca33262d 100644 |
| --- a/arch/arm64/kernel/kgdb.c |
| +++ b/arch/arm64/kernel/kgdb.c |
| @@ -252,7 +252,7 @@ static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr) |
| if (!kgdb_single_step) |
| return DBG_HOOK_ERROR; |
| |
| - kgdb_handle_exception(1, SIGTRAP, 0, regs); |
| + kgdb_handle_exception(0, SIGTRAP, 0, regs); |
| return DBG_HOOK_HANDLED; |
| } |
| NOKPROBE_SYMBOL(kgdb_step_brk_fn); |
| -- |
| 2.25.1 |
| |