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authorRussell Currey <ruscur@russell.cc>2023-08-23 08:53:17 +0300
committerMichael Ellerman <mpe@ellerman.id.au>2023-08-24 15:33:17 +0300
commiteac030b22ea12cdfcbb2e941c21c03964403c63f (patch)
tree6e20ff95a5a5b8588b87160065d9a0d5b836a5a2 /arch/powerpc/platforms
parent1aa000667669fa855853decbb1c69e974d8ff716 (diff)
downloadlinux-eac030b22ea12cdfcbb2e941c21c03964403c63f.tar.xz
powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT
lppaca_shared_proc() takes a pointer to the lppaca which is typically accessed through get_lppaca(). With DEBUG_PREEMPT enabled, this leads to checking if preemption is enabled, for example: BUG: using smp_processor_id() in preemptible [00000000] code: grep/10693 caller is lparcfg_data+0x408/0x19a0 CPU: 4 PID: 10693 Comm: grep Not tainted 6.5.0-rc3 #2 Call Trace: dump_stack_lvl+0x154/0x200 (unreliable) check_preemption_disabled+0x214/0x220 lparcfg_data+0x408/0x19a0 ... This isn't actually a problem however, as it does not matter which lppaca is accessed, the shared proc state will be the same. vcpudispatch_stats_procfs_init() already works around this by disabling preemption, but the lparcfg code does not, erroring any time /proc/powerpc/lparcfg is accessed with DEBUG_PREEMPT enabled. Instead of disabling preemption on the caller side, rework lppaca_shared_proc() to not take a pointer and instead directly access the lppaca, bypassing any potential preemption checks. Fixes: f13c13a00512 ("powerpc: Stop using non-architected shared_proc field in lppaca") Signed-off-by: Russell Currey <ruscur@russell.cc> [mpe: Rework to avoid needing a definition in paca.h and lppaca.h] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230823055317.751786-4-mpe@ellerman.id.au
Diffstat (limited to 'arch/powerpc/platforms')
-rw-r--r--arch/powerpc/platforms/pseries/lpar.c10
-rw-r--r--arch/powerpc/platforms/pseries/lparcfg.c4
-rw-r--r--arch/powerpc/platforms/pseries/setup.c2
3 files changed, 4 insertions, 12 deletions
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 27fb656bd6ba..f2cb62148f36 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -640,16 +640,8 @@ static const struct proc_ops vcpudispatch_stats_freq_proc_ops = {
static int __init vcpudispatch_stats_procfs_init(void)
{
- /*
- * Avoid smp_processor_id while preemptible. All CPUs should have
- * the same value for lppaca_shared_proc.
- */
- preempt_disable();
- if (!lppaca_shared_proc(get_lppaca())) {
- preempt_enable();
+ if (!lppaca_shared_proc())
return 0;
- }
- preempt_enable();
if (!proc_create("powerpc/vcpudispatch_stats", 0600, NULL,
&vcpudispatch_stats_proc_ops))
diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
index 8acc70509520..1c151d77e74b 100644
--- a/arch/powerpc/platforms/pseries/lparcfg.c
+++ b/arch/powerpc/platforms/pseries/lparcfg.c
@@ -206,7 +206,7 @@ static void parse_ppp_data(struct seq_file *m)
ppp_data.active_system_procs);
/* pool related entries are appropriate for shared configs */
- if (lppaca_shared_proc(get_lppaca())) {
+ if (lppaca_shared_proc()) {
unsigned long pool_idle_time, pool_procs;
seq_printf(m, "pool=%d\n", ppp_data.pool_num);
@@ -560,7 +560,7 @@ static int pseries_lparcfg_data(struct seq_file *m, void *v)
partition_potential_processors);
seq_printf(m, "shared_processor_mode=%d\n",
- lppaca_shared_proc(get_lppaca()));
+ lppaca_shared_proc());
#ifdef CONFIG_PPC_64S_HASH_MMU
if (!radix_enabled())
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index bb0a9aeb50f9..ecea85c74c43 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -849,7 +849,7 @@ static void __init pSeries_setup_arch(void)
if (firmware_has_feature(FW_FEATURE_LPAR)) {
vpa_init(boot_cpuid);
- if (lppaca_shared_proc(get_lppaca())) {
+ if (lppaca_shared_proc()) {
static_branch_enable(&shared_processor);
pv_spinlocks_init();
#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING