From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH 6/6] powerpc/64s/interrupt: halt early boot interrupts if paca is not set up
Date: Thu, 15 Sep 2022 22:10:58 +1000 [thread overview]
Message-ID: <20220915121058.2288916-7-npiggin@gmail.com> (raw)
In-Reply-To: <20220915121058.2288916-1-npiggin@gmail.com>
Ensure r13 is zero from very early in boot until it gets set to the
boot paca pointer. This allows early program and mce handlers to halt
if there is no valid paca, rather than potentially run off into the
weeds. This preserves register and memory contents for low level
debugging tools.
Nothing could be printed to console at this point in any case because
even udbg is only set up after the boot paca is set, so this shouldn't
be missed.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/kernel/exceptions-64s.S | 11 +++++++++--
arch/powerpc/kernel/head_64.S | 3 +++
arch/powerpc/kernel/setup_64.c | 1 +
3 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 29d701a20c41..5078b2578dbe 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -724,8 +724,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
* userspace starts.
*/
.macro EARLY_BOOT_FIXUP
-#ifdef CONFIG_CPU_LITTLE_ENDIAN
BEGIN_FTR_SECTION
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
tdi 0,0,0x48 // Trap never, or in reverse endian: b . + 8
b 2f // Skip trampoline if endian is correct
.long 0xa643707d // mtsprg 0, r11 Backup r11
@@ -753,8 +753,15 @@ BEGIN_FTR_SECTION
mtsrr0 r11 // Restore SRR0
mfsprg r11, 0 // Restore r11
2:
-END_FTR_SECTION(0, 1) // nop out after boot
#endif
+ /*
+ * program check could hit at any time, and pseries can not block
+ * MSR[ME] in early boot. So check if there is anything useful in r13
+ * yet, and spin forever if not.
+ */
+ cmpdi r13,0
+ beq .
+END_FTR_SECTION(0, 1) // nop out after boot
.endm
/*
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index cf2c08902c05..6aeba8a9814e 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -494,6 +494,9 @@ __start_initialization_multiplatform:
/* Make sure we are running in 64 bits mode */
bl enable_64b_mode
+ /* Zero r13 (paca) so early program check / mce don't use it */
+ li r13,0
+
/* Get TOC pointer (current runtime address) */
bl relative_toc
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 214d10caf458..d290ea9f0865 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -362,6 +362,7 @@ void __init early_setup(unsigned long dt_ptr)
*/
initialise_paca(&boot_paca, 0);
fixup_boot_paca(&boot_paca);
+ WARN_ON(local_paca != 0);
setup_paca(&boot_paca); /* install the paca into registers */
/* -------- printk is now safe to use ------- */
--
2.37.2
prev parent reply other threads:[~2022-09-15 12:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-15 12:10 [PATCH 0/6] powerpc/64: improve boot debugging Nicholas Piggin
2022-09-15 12:10 ` [PATCH 1/6] powerpc/64: mark irqs hard disabled in boot paca Nicholas Piggin
2022-09-15 12:10 ` [PATCH 2/6] powerpc/64s/interrupt: move early boot ILE fixup into a macro Nicholas Piggin
2022-09-15 12:10 ` [PATCH 3/6] powerpc/64s: early boot machine check handler Nicholas Piggin
2022-09-15 12:10 ` [PATCH 4/6] powerpc/64: avoid using r13 in relocate Nicholas Piggin
2022-09-15 12:10 ` [PATCH 5/6] powerpc/64: don't set boot CPU's r13 to paca until the structure is set up Nicholas Piggin
2022-09-15 12:10 ` Nicholas Piggin [this message]
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