[PATCH AUTOSEL 4.19 06/21] powerpc/pci: Add ppc_md.discover_phbs()

[PATCH AUTOSEL 4.19 06/21] powerpc/pci: Add ppc_md.discover_phbs()

[Sasha Levin]

From: Oliver O'Halloran <oohall@gmail.com>

[ Upstream commit 5537fcb319d016ce387f818dd774179bc03217f5 ]

On many powerpc platforms the discovery and initalisation of
pci_controllers (PHBs) happens inside of setup_arch(). This is very early
in boot (pre-initcalls) and means that we're initialising the PHB long
before many basic kernel services (slab allocator, debugfs, a real ioremap)
are available.

On PowerNV this causes an additional problem since we map the PHB registers
with ioremap(). As of commit d538aadc2718 ("powerpc/ioremap: warn on early
use of ioremap()") a warning is printed because we're using the "incorrect"
API to setup and MMIO mapping in searly boot. The kernel does provide
early_ioremap(), but that is not intended to create long-lived MMIO
mappings and a seperate warning is printed by generic code if
early_ioremap() mappings are "leaked."

This is all fixable with dumb hacks like using early_ioremap() to setup
the initial mapping then replacing it with a real ioremap later on in
boot, but it does raise the question: Why the hell are we setting up the
PHB's this early in boot?

The old and wise claim it's due to "hysterical rasins." Aside from amused
grapes there doesn't appear to be any real reason to maintain the current
behaviour. Already most of the newer embedded platforms perform PHB
discovery in an arch_initcall and between the end of setup_arch() and the
start of initcalls none of the generic kernel code does anything PCI
related. On powerpc scanning PHBs occurs in a subsys_initcall so it should
be possible to move the PHB discovery to a core, postcore or arch initcall.

This patch adds the ppc_md.discover_phbs hook and a core_initcall stub that
calls it. The core_initcalls are the earliest to be called so this will
any possibly issues with dependency between initcalls. This isn't just an
academic issue either since on pseries and PowerNV EEH init occurs in an
arch_initcall and depends on the pci_controllers being available, similarly
the creation of pci_dns occurs at core_initcall_sync (i.e. between core and
postcore initcalls). These problems need to be addressed seperately.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
[mpe: Make discover_phbs() static]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201103043523.916109-1-oohall@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/include/asm/machdep.h |  3 +++
 arch/powerpc/kernel/pci-common.c   | 10 ++++++++++
 2 files changed, 13 insertions(+)

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index a47de82fb8e2..bda87cbf106d 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -71,6 +71,9 @@ struct machdep_calls {
 	int		(*pcibios_root_bridge_prepare)(struct pci_host_bridge
 				*bridge);
 
+	/* finds all the pci_controllers present at boot */
+	void 		(*discover_phbs)(void);
+
 	/* To setup PHBs when using automatic OF platform driver for PCI */
 	int		(*pci_setup_phb)(struct pci_controller *host);
 
diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 88e4f69a09e5..74628aca2bf1 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c
@@ -1671,3 +1671,13 @@ static void fixup_hide_host_resource_fsl(struct pci_dev *dev)
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_MOTOROLA, PCI_ANY_ID, fixup_hide_host_resource_fsl);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_FREESCALE, PCI_ANY_ID, fixup_hide_host_resource_fsl);
+
+
+static int __init discover_phbs(void)
+{
+	if (ppc_md.discover_phbs)
+		ppc_md.discover_phbs();
+
+	return 0;
+}
+core_initcall(discover_phbs);
-- 
2.30.1

[PATCH AUTOSEL 4.19 07/21] powerpc: improve handling of unrecoverable system reset

[Sasha Levin]

From: Nicholas Piggin <npiggin@gmail.com>

[ Upstream commit 11cb0a25f71818ca7ab4856548ecfd83c169aa4d ]

If an unrecoverable system reset hits in process context, the system
does not have to panic. Similar to machine check, call nmi_exit()
before die().

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210130130852.2952424-26-npiggin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/kernel/traps.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 1b2d84cb373b..2379c4bf3979 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -433,8 +433,11 @@ out:
 		die("Unrecoverable nested System Reset", regs, SIGABRT);
 #endif
 	/* Must die if the interrupt is not recoverable */
-	if (!(regs->msr & MSR_RI))
+	if (!(regs->msr & MSR_RI)) {
+		/* For the reason explained in die_mce, nmi_exit before die */
+		nmi_exit();
 		die("Unrecoverable System Reset", regs, SIGABRT);
+	}
 
 	if (!nested)
 		nmi_exit();
-- 
2.30.1

[PATCH AUTOSEL 4.19 08/21] powerpc/perf: Record counter overflow always if SAMPLE_IP is unset

[Sasha Levin]

From: Athira Rajeev <atrajeev@linux.vnet.ibm.com>

[ Upstream commit d137845c973147a22622cc76c7b0bc16f6206323 ]

While sampling for marked events, currently we record the sample only
if the SIAR valid bit of Sampled Instruction Event Register (SIER) is
set. SIAR_VALID bit is used for fetching the instruction address from
Sampled Instruction Address Register(SIAR). But there are some
usecases, where the user is interested only in the PMU stats at each
counter overflow and the exact IP of the overflow event is not
required. Dropping SIAR invalid samples will fail to record some of
the counter overflows in such cases.

Example of such usecase is dumping the PMU stats (event counts) after
some regular amount of instructions/events from the userspace (ex: via
ptrace). Here counter overflow is indicated to userspace via signal
handler, and captured by monitoring and enabling I/O signaling on the
event file descriptor. In these cases, we expect to get
sample/overflow indication after each specified sample_period.

Perf event attribute will not have PERF_SAMPLE_IP set in the
sample_type if exact IP of the overflow event is not requested. So
while profiling if SAMPLE_IP is not set, just record the counter
overflow irrespective of SIAR_VALID check.

Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
[mpe: Reflow comment and if formatting]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1612516492-1428-1-git-send-email-atrajeev@linux.vnet.ibm.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/powerpc/perf/core-book3s.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index 70de13822828..091bdeaf02a3 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -2046,7 +2046,17 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
 			left += period;
 			if (left <= 0)
 				left = period;
-			record = siar_valid(regs);
+
+			/*
+			 * If address is not requested in the sample via
+			 * PERF_SAMPLE_IP, just record that sample irrespective
+			 * of SIAR valid check.
+			 */
+			if (event->attr.sample_type & PERF_SAMPLE_IP)
+				record = siar_valid(regs);
+			else
+				record = 1;
+
 			event->hw.last_period = event->hw.sample_period;
 		}
 		if (left < 0x80000000LL)
@@ -2064,9 +2074,10 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
 	 * MMCR2. Check attr.exclude_kernel and address to drop the sample in
 	 * these cases.
 	 */
-	if (event->attr.exclude_kernel && record)
-		if (is_kernel_addr(mfspr(SPRN_SIAR)))
-			record = 0;
+	if (event->attr.exclude_kernel &&
+	    (event->attr.sample_type & PERF_SAMPLE_IP) &&
+	    is_kernel_addr(mfspr(SPRN_SIAR)))
+		record = 0;
 
 	/*
 	 * Finally record data if requested.
-- 
2.30.1