6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Juergen Gross jgross@suse.com
[ Upstream commit 715ad3e0ec2b13c27335749f27a5c9f0c0e84064 ]
Initializing a percpu variable with the address of a struct tagged as .initdata is breaking the build with CONFIG_SECTION_MISMATCH_WARN_ONLY not set to "y".
Fix that by using an access function instead returning the .initdata struct address if the percpu space of the struct hasn't been allocated yet.
Fixes: 368990a7fe30 ("xen: fix multicall debug data referencing") Reported-by: Borislav Petkov bp@alien8.de Reviewed-by: Boris Ostrovsky boris.ostrovsky@oracle.com Acked-by: "Borislav Petkov (AMD)" bp@alien8.de Tested-by: "Borislav Petkov (AMD)" bp@alien8.de Signed-off-by: Juergen Gross jgross@suse.com Message-ID: 20250327190602.26015-1-jgross@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/xen/multicalls.c | 26 ++++++++++++++------------ arch/x86/xen/smp_pv.c | 1 - arch/x86/xen/xen-ops.h | 3 --- 3 files changed, 14 insertions(+), 16 deletions(-)
diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c index 10c660fae8b30..7237d56a9d3f0 100644 --- a/arch/x86/xen/multicalls.c +++ b/arch/x86/xen/multicalls.c @@ -54,14 +54,20 @@ struct mc_debug_data {
static DEFINE_PER_CPU(struct mc_buffer, mc_buffer); static struct mc_debug_data mc_debug_data_early __initdata; -static DEFINE_PER_CPU(struct mc_debug_data *, mc_debug_data) = - &mc_debug_data_early; static struct mc_debug_data __percpu *mc_debug_data_ptr; DEFINE_PER_CPU(unsigned long, xen_mc_irq_flags);
static struct static_key mc_debug __ro_after_init; static bool mc_debug_enabled __initdata;
+static struct mc_debug_data * __ref get_mc_debug(void) +{ + if (!mc_debug_data_ptr) + return &mc_debug_data_early; + + return this_cpu_ptr(mc_debug_data_ptr); +} + static int __init xen_parse_mc_debug(char *arg) { mc_debug_enabled = true; @@ -71,20 +77,16 @@ static int __init xen_parse_mc_debug(char *arg) } early_param("xen_mc_debug", xen_parse_mc_debug);
-void mc_percpu_init(unsigned int cpu) -{ - per_cpu(mc_debug_data, cpu) = per_cpu_ptr(mc_debug_data_ptr, cpu); -} - static int __init mc_debug_enable(void) { unsigned long flags; + struct mc_debug_data __percpu *mcdb;
if (!mc_debug_enabled) return 0;
- mc_debug_data_ptr = alloc_percpu(struct mc_debug_data); - if (!mc_debug_data_ptr) { + mcdb = alloc_percpu(struct mc_debug_data); + if (!mcdb) { pr_err("xen_mc_debug inactive\n"); static_key_slow_dec(&mc_debug); return -ENOMEM; @@ -93,7 +95,7 @@ static int __init mc_debug_enable(void) /* Be careful when switching to percpu debug data. */ local_irq_save(flags); xen_mc_flush(); - mc_percpu_init(0); + mc_debug_data_ptr = mcdb; local_irq_restore(flags);
pr_info("xen_mc_debug active\n"); @@ -155,7 +157,7 @@ void xen_mc_flush(void) trace_xen_mc_flush(b->mcidx, b->argidx, b->cbidx);
if (static_key_false(&mc_debug)) { - mcdb = __this_cpu_read(mc_debug_data); + mcdb = get_mc_debug(); memcpy(mcdb->entries, b->entries, b->mcidx * sizeof(struct multicall_entry)); } @@ -235,7 +237,7 @@ struct multicall_space __xen_mc_entry(size_t args)
ret.mc = &b->entries[b->mcidx]; if (static_key_false(&mc_debug)) { - struct mc_debug_data *mcdb = __this_cpu_read(mc_debug_data); + struct mc_debug_data *mcdb = get_mc_debug();
mcdb->caller[b->mcidx] = __builtin_return_address(0); mcdb->argsz[b->mcidx] = args; diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c index 6863d3da7decf..7ea57f728b89d 100644 --- a/arch/x86/xen/smp_pv.c +++ b/arch/x86/xen/smp_pv.c @@ -305,7 +305,6 @@ static int xen_pv_kick_ap(unsigned int cpu, struct task_struct *idle) return rc;
xen_pmu_init(cpu); - mc_percpu_init(cpu);
/* * Why is this a BUG? If the hypercall fails then everything can be diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h index 63c13a2ccf556..25e318ef27d6b 100644 --- a/arch/x86/xen/xen-ops.h +++ b/arch/x86/xen/xen-ops.h @@ -261,9 +261,6 @@ void xen_mc_callback(void (*fn)(void *), void *data); */ struct multicall_space xen_mc_extend_args(unsigned long op, size_t arg_size);
-/* Do percpu data initialization for multicalls. */ -void mc_percpu_init(unsigned int cpu); - extern bool is_xen_pmu;
irqreturn_t xen_pmu_irq_handler(int irq, void *dev_id);