| Message ID | 20220420065013.222816-21-npiggin@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | gdbserver multi-threaded debugging and POWER9/10 support | expand |
On Wed, 20 Apr 2022 at 06:51, Nicholas Piggin <npiggin@gmail.com> wrote: > > POWER9 has a strange problem with attn, but otherwise gdbserver > works well. Enable it. > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Reviewed-by: Joel Stanley <joel@jms.id.au> > --- > README.md | 14 +++++++++++--- > src/pdbgproxy.c | 29 +++++++++++++++++++++++++---- > 2 files changed, 36 insertions(+), 7 deletions(-) > > diff --git a/README.md b/README.md > index 9ece33f9..ba17c613 100644 > --- a/README.md > +++ b/README.md > @@ -534,8 +534,9 @@ There are also low level htm commands which can also be used: > - `dump` will dump the trace to a file. > > ### GDBSERVER > -At the moment gdbserver is only supported on P8 while the cores are in the > -kernel. > +At the moment gdbserver is only supported on P8 and P9. > + > +Memory access can only be performed on kernel memory. > > To run a gdbserver on a P8 machine from a BMC running openbmc: > > @@ -547,7 +548,7 @@ $ ./pdbg -d p8 -p0 -c11 -t0 gdbserver 44 > > On your local machine: > $ gdb > -(gdb) set architecture powerpc:common64 > +(gdb) set architecture powerpc:common64 > (gdb) target remote palm5-bmc:44 > > Debugging info: > @@ -566,6 +567,13 @@ Notes: > happen. > 2. If you want to view the kernel call trace then run gdb on the vmlinux that > the host is running (the kernel needs to be compiled with debug symbols). > +3. The kernel HARDLOCKUP watchdog can interact badly with GDBSERVER (and all > +pdbg direct controls for that matter). Disabling it before debugging is a > +good idea. > +4. Idle states have often had problems with pdbg direct controls. If things are > +misbehaving, booting Linux with powersave=off is the first thing to try. > +5. attn instructions seem to cause host hangs on POWER9. gdb breakpoints should > +not be used. > > ## Submitting patches > > diff --git a/src/pdbgproxy.c b/src/pdbgproxy.c > index 4c7b4a82..3028d418 100644 > --- a/src/pdbgproxy.c > +++ b/src/pdbgproxy.c > @@ -105,6 +105,9 @@ static void detach(uint64_t *stack, void *priv) > > #define POWER8_HID_ENABLE_ATTN PPC_BIT(31) > > +#define POWER9_HID_ENABLE_ATTN PPC_BIT(3) > +#define POWER9_HID_FLUSH_ICACHE PPC_BIT(2) > + > static int set_attn(bool enable) > { > uint64_t hid; > @@ -122,6 +125,17 @@ static int set_attn(bool enable) > return 0; > hid &= ~POWER8_HID_ENABLE_ATTN; > } > + } else if (pdbg_target_compatible(thread_target, "ibm,power9-thread")) { > + if (enable) { > + if (hid & POWER9_HID_ENABLE_ATTN) > + return 0; > + hid |= POWER9_HID_ENABLE_ATTN; > + } else { > + if (!(hid & POWER9_HID_ENABLE_ATTN)) > + return 0; > + hid &= ~POWER9_HID_ENABLE_ATTN; > + } > + hid |= POWER9_HID_FLUSH_ICACHE; > } else { > return -1; > } > @@ -658,13 +672,20 @@ static int gdbserver(uint16_t port) > return 0; > } > > - // > - // Temporary until I can get this working a bit smoother on p9 > - if (!pdbg_target_compatible(thread, "ibm,power8-thread")) { > - PR_ERROR("GDBSERVER is only available on POWER8\n"); > + if (!pdbg_target_compatible(thread, "ibm,power8-thread") && > + !pdbg_target_compatible(thread, "ibm,power9-thread")) { > + PR_ERROR("GDBSERVER is only available on POWER8 and POWER9\n"); > return -1; > } > > + if (pdbg_target_compatible(thread, "ibm,power9-thread")) { > + /* > + * XXX: If we advertise no swbreak support on POWER9 does > + * that prevent the client using them? > + */ > + PR_WARNING("Breakpoints may cause host crashes on POWER9 and should not be used\n"); > + } > + > /* Check endianess in MSR */ > rc = thread_getmsr(thread, &msr); > if (rc) { > -- > 2.35.1 > > -- > Pdbg mailing list > Pdbg@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/pdbg
diff --git a/README.md b/README.md index 9ece33f9..ba17c613 100644 --- a/README.md +++ b/README.md @@ -534,8 +534,9 @@ There are also low level htm commands which can also be used: - `dump` will dump the trace to a file. ### GDBSERVER -At the moment gdbserver is only supported on P8 while the cores are in the -kernel. +At the moment gdbserver is only supported on P8 and P9. + +Memory access can only be performed on kernel memory. To run a gdbserver on a P8 machine from a BMC running openbmc: @@ -547,7 +548,7 @@ $ ./pdbg -d p8 -p0 -c11 -t0 gdbserver 44 On your local machine: $ gdb -(gdb) set architecture powerpc:common64 +(gdb) set architecture powerpc:common64 (gdb) target remote palm5-bmc:44 Debugging info: @@ -566,6 +567,13 @@ Notes: happen. 2. If you want to view the kernel call trace then run gdb on the vmlinux that the host is running (the kernel needs to be compiled with debug symbols). +3. The kernel HARDLOCKUP watchdog can interact badly with GDBSERVER (and all +pdbg direct controls for that matter). Disabling it before debugging is a +good idea. +4. Idle states have often had problems with pdbg direct controls. If things are +misbehaving, booting Linux with powersave=off is the first thing to try. +5. attn instructions seem to cause host hangs on POWER9. gdb breakpoints should +not be used. ## Submitting patches diff --git a/src/pdbgproxy.c b/src/pdbgproxy.c index 4c7b4a82..3028d418 100644 --- a/src/pdbgproxy.c +++ b/src/pdbgproxy.c @@ -105,6 +105,9 @@ static void detach(uint64_t *stack, void *priv) #define POWER8_HID_ENABLE_ATTN PPC_BIT(31) +#define POWER9_HID_ENABLE_ATTN PPC_BIT(3) +#define POWER9_HID_FLUSH_ICACHE PPC_BIT(2) + static int set_attn(bool enable) { uint64_t hid; @@ -122,6 +125,17 @@ static int set_attn(bool enable) return 0; hid &= ~POWER8_HID_ENABLE_ATTN; } + } else if (pdbg_target_compatible(thread_target, "ibm,power9-thread")) { + if (enable) { + if (hid & POWER9_HID_ENABLE_ATTN) + return 0; + hid |= POWER9_HID_ENABLE_ATTN; + } else { + if (!(hid & POWER9_HID_ENABLE_ATTN)) + return 0; + hid &= ~POWER9_HID_ENABLE_ATTN; + } + hid |= POWER9_HID_FLUSH_ICACHE; } else { return -1; } @@ -658,13 +672,20 @@ static int gdbserver(uint16_t port) return 0; } - // - // Temporary until I can get this working a bit smoother on p9 - if (!pdbg_target_compatible(thread, "ibm,power8-thread")) { - PR_ERROR("GDBSERVER is only available on POWER8\n"); + if (!pdbg_target_compatible(thread, "ibm,power8-thread") && + !pdbg_target_compatible(thread, "ibm,power9-thread")) { + PR_ERROR("GDBSERVER is only available on POWER8 and POWER9\n"); return -1; } + if (pdbg_target_compatible(thread, "ibm,power9-thread")) { + /* + * XXX: If we advertise no swbreak support on POWER9 does + * that prevent the client using them? + */ + PR_WARNING("Breakpoints may cause host crashes on POWER9 and should not be used\n"); + } + /* Check endianess in MSR */ rc = thread_getmsr(thread, &msr); if (rc) {
POWER9 has a strange problem with attn, but otherwise gdbserver works well. Enable it. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- README.md | 14 +++++++++++--- src/pdbgproxy.c | 29 +++++++++++++++++++++++++---- 2 files changed, 36 insertions(+), 7 deletions(-)