Get k(g)db working #140
Comments
|
Is that used by anyone on powerpc? I thought |
|
It's not used much because we've always had But really we should either get it working or prevent it from being enabled, I don't like having things that are known to not work sitting around for people to trip up on. |
mpe
referenced
this issue
in linuxppc/linux
Jun 18, 2018
While hacking on kTLS, I ran into the following panic from an unprivileged netserver / netperf TCP session: BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 PGD 800000037f378067 P4D 800000037f378067 PUD 3c0e61067 PMD 0 Oops: 0010 [#1] SMP KASAN PTI CPU: 1 PID: 2289 Comm: netserver Not tainted 4.17.0+ torvalds#139 Hardware name: LENOVO 20FBCTO1WW/20FBCTO1WW, BIOS N1FET47W (1.21 ) 11/28/2016 RIP: 0010: (null) Code: Bad RIP value. RSP: 0018:ffff88036abcf740 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: ffff88036f5f6800 RCX: 1ffff1006debed26 RDX: ffff88036abcf920 RSI: ffff8803cb1a4f00 RDI: ffff8803c258c280 RBP: ffff8803c258c280 R08: ffff8803c258c280 R09: ffffed006f559d48 R10: ffff88037aacea43 R11: ffffed006f559d49 R12: ffff8803c258c280 R13: ffff8803cb1a4f20 R14: 00000000000000db R15: ffffffffc168a350 FS: 00007f7e631f4700(0000) GS:ffff8803d1c80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000003ccf64005 CR4: 00000000003606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? tls_sw_poll+0xa4/0x160 [tls] ? sock_poll+0x20a/0x680 ? do_select+0x77b/0x11a0 ? poll_schedule_timeout.constprop.12+0x130/0x130 ? pick_link+0xb00/0xb00 ? read_word_at_a_time+0x13/0x20 ? vfs_poll+0x270/0x270 ? deref_stack_reg+0xad/0xe0 ? __read_once_size_nocheck.constprop.6+0x10/0x10 [...] Debugging further, it turns out that calling into ctx->sk_poll() is invalid since sk_poll itself is NULL which was saved from the original TCP socket in order for tls_sw_poll() to invoke it. Looks like the recent conversion from poll to poll_mask callback started in 1525242 ("net: add support for ->poll_mask in proto_ops") missed to eventually convert kTLS, too: TCP's ->poll was converted over to the ->poll_mask in commit 2c7d3da ("net/tcp: convert to ->poll_mask") and therefore kTLS wrongly saved the ->poll old one which is now NULL. Convert kTLS over to use ->poll_mask instead. Also instead of POLLIN | POLLRDNORM use the proper EPOLLIN | EPOLLRDNORM bits as the case in tcp_poll_mask() as well that is mangled here. Fixes: 2c7d3da ("net/tcp: convert to ->poll_mask") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Christoph Hellwig <hch@lst.de> Cc: Dave Watson <davejwatson@fb.com> Tested-by: Dave Watson <davejwatson@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
|
Tried it on 8xx, no Oops, but uggly 'ptrval'. Should we do something about it ? But it silently hangs after calling 'help' |
|
bta silently hangs as well |
|
Those silent hangs are in fact a problem in CPM serial driver. |
|
When booting with parameter 'debug_boot_weak_hash', I get the following Seems like kdb_getarea tries to access hashed address and not real address (The 0xba99ad80 in first line is written by %p while kdb_getarea() uses %lx |
|
The issue seems to be linked to the following call:
On the 8xx, we end up with On faster platforms, we most likely end up with an hashed pointer, which is by definition a non valid address hence the Oops. |
|
When replacing that Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry |
|
See https://patchwork.ozlabs.org/patch/969879/ @mpe, does it fix the issue you reported ? |
fengguang
referenced
this issue
in 0day-ci/linux
Sep 14, 2018
On a powerpc 8xx, 'btc' fails as follows: Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0x0 when booting the kernel with 'debug_boot_weak_hash', it fails as well Entering kdb (current=0xba99ad80, pid 284) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0xba99ad80 On other platforms, Oopses have been observed too, see https://github.com/linuxppc/linux/issues/139 This is due to btc calling 'btt' with %p pointer as an argument. This patch replaces %p by %px to get the real pointer value as expected by 'btt' Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Cc: <stable@vger.kernel.org> # 4.15+
|
It helps, it makes But the selftests still crash. |
|
Apparently, it works on the 8xx: |
|
Seems to work properly on 83xx as well: |
|
@mpe, it seems you get a program check from somewhere else than expected:
Then the second program check is the WARN_ON in eprintk() called from check_and_rewind_pc() Could you tell what is at |
|
In the meantime, I discovered that kdb was left over when we implemented STRICT_KERNEL_RWX. The following patch fixes setting the breakpoint with STRICT_KERNEL_RWX is active: |
|
I've fixed the breakpoint mismatch. On LE we need to use Now it's getting to the singlestep test, which seems to be getting stuck. |
|
Not sure if you want to track this here but I see that the hvc driver only sends KGDB output to hvc0, regardless of kgdboc value in the boot line: From drivers/tty/hvc/hvc_console.c: This is particularly relevant when using QEMU with |
|
I am testing this on 4.19 kernel, and this is what I get, not sure if it is related, or I am mis-using it: Looking at the failing instruction, I see: Looking at the code, I see: So, it means that tty is null, and it is being de-referenced by driver_data |
pull bot
referenced
this issue
in lokeshbv/linux
Nov 14, 2018
On a powerpc 8xx, 'btc' fails as follows: Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0x0 when booting the kernel with 'debug_boot_weak_hash', it fails as well Entering kdb (current=0xba99ad80, pid 284) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0xba99ad80 On other platforms, Oopses have been observed too, see https://github.com/linuxppc/linux/issues/139 This is due to btc calling 'btt' with %p pointer as an argument. This patch replaces %p by %px to get the real pointer value as expected by 'btt' Fixes: ad67b74 ("printk: hash addresses printed with %p") Cc: <stable@vger.kernel.org> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
plbossart
referenced
this issue
in plbossart/sound
Nov 15, 2018
On a powerpc 8xx, 'btc' fails as follows: Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0x0 when booting the kernel with 'debug_boot_weak_hash', it fails as well Entering kdb (current=0xba99ad80, pid 284) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0xba99ad80 On other platforms, Oopses have been observed too, see https://github.com/linuxppc/linux/issues/139 This is due to btc calling 'btt' with %p pointer as an argument. This patch replaces %p by %px to get the real pointer value as expected by 'btt' Fixes: ad67b74 ("printk: hash addresses printed with %p") Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Cc: <stable@vger.kernel.org> # 4.15+ Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com> (cherry picked from commit a0ca72c git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb.git kgdb-next) BUG=chromium:900598 TEST=kgdb works better Change-Id: I5ecb3860244f98d1ae17edcd7d95398b101ca85a Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/1310053 Reviewed-by: Guenter Roeck <groeck@chromium.org>
|
Following fixes are now in 4.20: |
woodsts
referenced
this issue
in woodsts/linux-stable
Nov 21, 2018
commit dded2e1 upstream. On a powerpc 8xx, 'btc' fails as follows: Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0x0 when booting the kernel with 'debug_boot_weak_hash', it fails as well Entering kdb (current=0xba99ad80, pid 284) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0xba99ad80 On other platforms, Oopses have been observed too, see https://github.com/linuxppc/linux/issues/139 This is due to btc calling 'btt' with %p pointer as an argument. This patch replaces %p by %px to get the real pointer value as expected by 'btt' Fixes: ad67b74 ("printk: hash addresses printed with %p") Cc: <stable@vger.kernel.org> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
woodsts
referenced
this issue
in woodsts/linux-stable
Nov 21, 2018
commit dded2e1 upstream. On a powerpc 8xx, 'btc' fails as follows: Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0x0 when booting the kernel with 'debug_boot_weak_hash', it fails as well Entering kdb (current=0xba99ad80, pid 284) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0xba99ad80 On other platforms, Oopses have been observed too, see https://github.com/linuxppc/linux/issues/139 This is due to btc calling 'btt' with %p pointer as an argument. This patch replaces %p by %px to get the real pointer value as expected by 'btt' Fixes: ad67b74 ("printk: hash addresses printed with %p") Cc: <stable@vger.kernel.org> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
woodsts
referenced
this issue
in woodsts/linux-stable
Nov 21, 2018
commit dded2e1 upstream. On a powerpc 8xx, 'btc' fails as follows: Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0x0 when booting the kernel with 'debug_boot_weak_hash', it fails as well Entering kdb (current=0xba99ad80, pid 284) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0xba99ad80 On other platforms, Oopses have been observed too, see https://github.com/linuxppc/linux/issues/139 This is due to btc calling 'btt' with %p pointer as an argument. This patch replaces %p by %px to get the real pointer value as expected by 'btt' Fixes: ad67b74 ("printk: hash addresses printed with %p") Cc: <stable@vger.kernel.org> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
dsd
referenced
this issue
in endlessm/linux
Nov 27, 2018
BugLink: https://bugs.launchpad.net/bugs/1805158 commit dded2e1 upstream. On a powerpc 8xx, 'btc' fails as follows: Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0x0 when booting the kernel with 'debug_boot_weak_hash', it fails as well Entering kdb (current=0xba99ad80, pid 284) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0xba99ad80 On other platforms, Oopses have been observed too, see https://github.com/linuxppc/linux/issues/139 This is due to btc calling 'btt' with %p pointer as an argument. This patch replaces %p by %px to get the real pointer value as expected by 'btt' Fixes: ad67b74 ("printk: hash addresses printed with %p") Cc: <stable@vger.kernel.org> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
isjerryxiao
referenced
this issue
in isjerryxiao/Amlogic_s905-kernel
Nov 27, 2018
commit dded2e1 upstream. On a powerpc 8xx, 'btc' fails as follows: Entering kdb (current=0x(ptrval), pid 282) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0x0 when booting the kernel with 'debug_boot_weak_hash', it fails as well Entering kdb (current=0xba99ad80, pid 284) due to Keyboard Entry kdb> btc btc: cpu status: Currently on cpu 0 Available cpus: 0 kdb_getarea: Bad address 0xba99ad80 On other platforms, Oopses have been observed too, see https://github.com/linuxppc/linux/issues/139 This is due to btc calling 'btt' with %p pointer as an argument. This patch replaces %p by %px to get the real pointer value as expected by 'btt' Fixes: ad67b74 ("printk: hash addresses printed with %p") Cc: <stable@vger.kernel.org> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
Are there still issues with kgdb ? |
|
I'm seeing the bug in #140 (comment) still happening with 5.8.0-rc4, so I don't think kgdb works with the hvc driver currently. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
The very basics work, eg:
But then other things oops, in particular the self tests blow up.
The text was updated successfully, but these errors were encountered: