From: Hari Bathini hbathini@linux.ibm.com
[ Upstream commit 219572d2fc4135b5ce65c735d881787d48b10e71 ]
Kdump can be triggered after panic_notifers since commit f06e5153f4ae2 ("kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump after panic_notifers") introduced crash_kexec_post_notifiers option. But using this option would mean smp_send_stop(), that marks all other CPUs as offline, gets called before kdump is triggered. As a result, kdump routines fail to save other CPUs' registers. To fix this, kdump friendly crash_smp_send_stop() function was introduced with kernel commit 0ee59413c967 ("x86/panic: replace smp_send_stop() with kdump friendly version in panic path"). Override this kdump friendly weak function to handle crash_kexec_post_notifiers option appropriately on powerpc.
Reported-by: kernel test robot lkp@intel.com Signed-off-by: Hari Bathini hbathini@linux.ibm.com [Fixed signature of crash_stop_this_cpu() - reported by lkp@intel.com] Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20211207103719.91117-1-hbathini@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/kernel/smp.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+)
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c index 50aeef08aa470..d993f28107afa 100644 --- a/arch/powerpc/kernel/smp.c +++ b/arch/powerpc/kernel/smp.c @@ -594,6 +594,36 @@ void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *)) } #endif
+#ifdef CONFIG_NMI_IPI +static void crash_stop_this_cpu(struct pt_regs *regs) +#else +static void crash_stop_this_cpu(void *dummy) +#endif +{ + /* + * Just busy wait here and avoid marking CPU as offline to ensure + * register data is captured appropriately. + */ + while (1) + cpu_relax(); +} + +void crash_smp_send_stop(void) +{ + static bool stopped = false; + + if (stopped) + return; + + stopped = true; + +#ifdef CONFIG_NMI_IPI + smp_send_nmi_ipi(NMI_IPI_ALL_OTHERS, crash_stop_this_cpu, 1000000); +#else + smp_call_function(crash_stop_this_cpu, NULL, 0); +#endif /* CONFIG_NMI_IPI */ +} + #ifdef CONFIG_NMI_IPI static void nmi_stop_this_cpu(struct pt_regs *regs) {