linux-kernel - [PATCH v2] powerpc: Don't use %pK through printk

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Message-Id: <20250718-restricted-pointers-powerpc-v2-1-fd7bddd809f3@linutronix.de>
Date: Fri, 18 Jul 2025 15:20:25 +0200
From: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
To: Mahesh J Salgaonkar <mahesh@...ux.ibm.com>, 
 Oliver O'Halloran <oohall@...il.com>, 
 Madhavan Srinivasan <maddy@...ux.ibm.com>, 
 Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>, 
 Christophe Leroy <christophe.leroy@...roup.eu>, 
 Naveen N Rao <naveen@...nel.org>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org, 
 Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Subject: [PATCH v2] powerpc: Don't use %pK through printk

In the past %pK was preferable to %p as it would not leak raw pointer
values into the kernel log.
Since commit ad67b74d2469 ("printk: hash addresses printed with %p")
the regular %p has been improved to avoid this issue.
Furthermore, restricted pointers ("%pK") were never meant to be used
through printk(). They can still unintentionally leak raw pointers or
acquire sleeping locks in atomic contexts.

Switch to the regular pointer formatting which is safer and
easier to reason about.

Link: https://lore.kernel.org/lkml/20250113171731-dc10e3c1-da64-4af0-b767-7c7070468023@linutronix.de/
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
---
Changes in v2:
- Rework commit message
- Link to v1: https://lore.kernel.org/r/20250217-restricted-pointers-powerpc-v1-1-32c6bff63c9a@linutronix.de
---
 arch/powerpc/kernel/eeh_driver.c | 2 +-
 arch/powerpc/perf/hv-24x7.c      | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
index 7efe04c68f0fe3fb1c3c13d97d58e79e47cf103b..10ce6b3bd3b7c54f91544ae7f7fd3f32a51ee09a 100644
--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -907,7 +907,7 @@ void eeh_handle_normal_event(struct eeh_pe *pe)
 		/* FIXME: Use the same format as dump_stack() */
 		pr_err("EEH: Call Trace:\n");
 		for (i = 0; i < pe->trace_entries; i++)
-			pr_err("EEH: [%pK] %pS\n", ptrs[i], ptrs[i]);
+			pr_err("EEH: [%p] %pS\n", ptrs[i], ptrs[i]);
 
 		pe->trace_entries = 0;
 	}
diff --git a/arch/powerpc/perf/hv-24x7.c b/arch/powerpc/perf/hv-24x7.c
index 681cf85af2b327785acfa64bfce13c37cabacba3..e42677cc254a9a048ca20a34b654132b810bef22 100644
--- a/arch/powerpc/perf/hv-24x7.c
+++ b/arch/powerpc/perf/hv-24x7.c
@@ -713,12 +713,12 @@ static ssize_t catalog_event_len_validate(struct hv_24x7_event_data *event,
 	ev_len = be16_to_cpu(event->length);
 
 	if (ev_len % 16)
-		pr_info("event %zu has length %zu not divisible by 16: event=%pK\n",
+		pr_info("event %zu has length %zu not divisible by 16: event=%p\n",
 				event_idx, ev_len, event);
 
 	ev_end = (__u8 *)event + ev_len;
 	if (ev_end > end) {
-		pr_warn("event %zu has .length=%zu, ends after buffer end: ev_end=%pK > end=%pK, offset=%zu\n",
+		pr_warn("event %zu has .length=%zu, ends after buffer end: ev_end=%p > end=%p, offset=%zu\n",
 				event_idx, ev_len, ev_end, end,
 				offset);
 		return -1;
@@ -726,14 +726,14 @@ static ssize_t catalog_event_len_validate(struct hv_24x7_event_data *event,
 
 	calc_ev_end = event_end(event, end);
 	if (!calc_ev_end) {
-		pr_warn("event %zu has a calculated length which exceeds buffer length %zu: event=%pK end=%pK, offset=%zu\n",
+		pr_warn("event %zu has a calculated length which exceeds buffer length %zu: event=%p end=%p, offset=%zu\n",
 			event_idx, event_data_bytes, event, end,
 			offset);
 		return -1;
 	}
 
 	if (calc_ev_end > ev_end) {
-		pr_warn("event %zu exceeds its own length: event=%pK, end=%pK, offset=%zu, calc_ev_end=%pK\n",
+		pr_warn("event %zu exceeds its own length: event=%p, end=%p, offset=%zu, calc_ev_end=%p\n",
 			event_idx, event, ev_end, offset, calc_ev_end);
 		return -1;
 	}

---
base-commit: d086c886ceb9f59dea6c3a9dae7eb89e780a20c9
change-id: 20250217-restricted-pointers-powerpc-f11876496464

Best regards,
-- 
Thomas Weißschuh <thomas.weissschuh@...utronix.de>