[PATCH 26/28] powerpc: Split systemcfg data out of vdso data page

From: Thomas Weißschuh
Date: Thu Oct 10 2024 - 03:53:11 EST

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The systemcfg data only has minimal overlap with the vdso data.
Splitting the two avoids mapping the implementation-defined vdso data
into /proc/ppc64/systemcfg.
It is also a preparation for the standardization of vdso data storage.

The only field actually used by both systemcfg and vdso is
tb_ticks_per_sec and it is only changed once during time_init().
Initialize it in both structures there.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@xxxxxxxxxxxxx>
---
arch/powerpc/include/asm/vdso_datapage.h | 32 ++++++----------------------
arch/powerpc/kernel/proc_powerpc.c | 25 +++++++++++++++++++++-
arch/powerpc/kernel/setup-common.c | 4 +++-
arch/powerpc/kernel/smp.c | 10 +++++----
arch/powerpc/kernel/time.c | 3 +++
arch/powerpc/kernel/vdso.c | 20 -----------------
arch/powerpc/platforms/powernv/smp.c | 4 +++-
arch/powerpc/platforms/pseries/hotplug-cpu.c | 4 +++-
8 files changed, 48 insertions(+), 54 deletions(-)

diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index 3d5862d4c4e1618a27840d9136e890870e78a761..8b91b1d34ff639a0efb80b9cdd7274f785643153 100644
--- a/arch/powerpc/include/asm/vdso_datapage.h
+++ b/arch/powerpc/include/asm/vdso_datapage.h
@@ -10,21 +10,6 @@
*/

-/*
- * Note about this structure:
- *
- * This structure was historically called systemcfg and exposed to
- * userland via /proc/ppc64/systemcfg. Unfortunately, this became an
- * ABI issue as some proprietary software started relying on being able
- * to mmap() it, thus we have to keep the base layout at least for a
- * few kernel versions.
- *
- * However, since ppc32 doesn't suffer from this backward handicap,
- * a simpler version of the data structure is used there with only the
- * fields actually used by the vDSO.
- *
- */
-
/*
* If the major version changes we are incompatible.
* Minor version changes are a hint.
@@ -40,13 +25,9 @@

#define SYSCALL_MAP_SIZE ((NR_syscalls + 31) / 32)

-/*
- * So here is the ppc64 backward compatible version
- */
-
#ifdef CONFIG_PPC64

-struct vdso_arch_data {
+struct systemcfg {
__u8 eye_catcher[16]; /* Eyecatcher: SYSTEMCFG:PPC64 0x00 */
struct { /* Systemcfg version numbers */
__u32 major; /* Major number 0x10 */
@@ -71,10 +52,12 @@ struct vdso_arch_data {
__u32 dcache_line_size; /* L1 d-cache line size 0x64 */
__u32 icache_size; /* L1 i-cache size 0x68 */
__u32 icache_line_size; /* L1 i-cache line size 0x6C */
+};

- /* those additional ones don't have to be located anywhere
- * special as they were not part of the original systemcfg
- */
+extern struct systemcfg *systemcfg;
+
+struct vdso_arch_data {
+ __u64 tb_ticks_per_sec; /* Timebase tics / sec */
__u32 dcache_block_size; /* L1 d-cache block size */
__u32 icache_block_size; /* L1 i-cache block size */
__u32 dcache_log_block_size; /* L1 d-cache log block size */
@@ -88,9 +71,6 @@ struct vdso_arch_data {

#else /* CONFIG_PPC64 */

-/*
- * And here is the simpler 32 bits version
- */
struct vdso_arch_data {
__u64 tb_ticks_per_sec; /* Timebase tics / sec */
__u32 syscall_map[SYSCALL_MAP_SIZE]; /* Map of syscalls */
diff --git a/arch/powerpc/kernel/proc_powerpc.c b/arch/powerpc/kernel/proc_powerpc.c
index 3bda365843e44357538651c6c24c11a41de2eb06..e8083e05a1d03f74d9f24bac99e3ab526368c8e2 100644
--- a/arch/powerpc/kernel/proc_powerpc.c
+++ b/arch/powerpc/kernel/proc_powerpc.c
@@ -4,6 +4,7 @@
*/

#include <linux/init.h>
+#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/kernel.h>
@@ -44,13 +45,35 @@ static const struct proc_ops page_map_proc_ops = {
.proc_mmap = page_map_mmap,
};

+static union {
+ struct systemcfg data;
+ u8 page[PAGE_SIZE];
+} systemcfg_data_store __page_aligned_data;
+struct systemcfg *systemcfg = &systemcfg_data_store.data;

static int __init proc_ppc64_init(void)
{
struct proc_dir_entry *pde;

+ strcpy((char *)systemcfg->eye_catcher, "SYSTEMCFG:PPC64");
+ systemcfg->version.major = SYSTEMCFG_MAJOR;
+ systemcfg->version.minor = SYSTEMCFG_MINOR;
+ systemcfg->processor = mfspr(SPRN_PVR);
+ /*
+ * Fake the old platform number for pSeries and add
+ * in LPAR bit if necessary
+ */
+ systemcfg->platform = 0x100;
+ if (firmware_has_feature(FW_FEATURE_LPAR))
+ systemcfg->platform |= 1;
+ systemcfg->physicalMemorySize = memblock_phys_mem_size();
+ systemcfg->dcache_size = ppc64_caches.l1d.size;
+ systemcfg->dcache_line_size = ppc64_caches.l1d.line_size;
+ systemcfg->icache_size = ppc64_caches.l1i.size;
+ systemcfg->icache_line_size = ppc64_caches.l1i.line_size;
+
pde = proc_create_data("powerpc/systemcfg", S_IFREG | 0444, NULL,
- &page_map_proc_ops, vdso_data);
+ &page_map_proc_ops, systemcfg);
if (!pde)
return 1;
proc_set_size(pde, PAGE_SIZE);
diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
index 943430077375a4e3c95f4ee9c8d38270081d557e..d0b32ff2bc8dedc5aa7afce17f07a5c7c255387c 100644
--- a/arch/powerpc/kernel/setup-common.c
+++ b/arch/powerpc/kernel/setup-common.c
@@ -560,7 +560,9 @@ void __init smp_setup_cpu_maps(void)
out:
of_node_put(dn);
}
- vdso_data->processorCount = num_present_cpus();
+#endif
+#ifdef CONFIG_PPC64_PROC_SYSTEMCFG
+ systemcfg->processorCount = num_present_cpus();
#endif /* CONFIG_PPC64 */

/* Initialize CPU <=> thread mapping/
diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 4ab9b8cee77a1a775b22ed041d62ca43c9e1f61d..87ae45bf1045d8974e3eed09e284bc582310f3e2 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1186,8 +1186,8 @@ int generic_cpu_disable(void)
return -EBUSY;

set_cpu_online(cpu, false);
-#ifdef CONFIG_PPC64
- vdso_data->processorCount--;
+#ifdef CONFIG_PPC64_PROC_SYSTEMCFG
+ systemcfg->processorCount--;
#endif
/* Update affinity of all IRQs previously aimed at this CPU */
irq_migrate_all_off_this_cpu();
@@ -1642,10 +1642,12 @@ void start_secondary(void *unused)

secondary_cpu_time_init();

-#ifdef CONFIG_PPC64
+#ifdef CONFIG_PPC64_PROC_SYSTEMCFG
if (system_state == SYSTEM_RUNNING)
- vdso_data->processorCount++;
+ systemcfg->processorCount++;
+#endif

+#ifdef CONFIG_PPC64
vdso_getcpu_init();
#endif
set_numa_node(numa_cpu_lookup_table[cpu]);
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 0ff9f038e800db6dbc910ce581550b457ee5f2db..6c53a0153c0d1c7cd74017a4dadb09ba149e456f 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -951,6 +951,9 @@ void __init time_init(void)
}

vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
+#ifdef CONFIG_PPC64_PROC_SYSTEMCFG
+ systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
+#endif

/* initialise and enable the large decrementer (if we have one) */
set_decrementer_max();
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index ee4b9d676cff546caced78f6dd76923239697a3c..924f7f4fa597ef4b78f3e8a11ea1c22909c9f0c2 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -16,7 +16,6 @@
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/security.h>
-#include <linux/memblock.h>
#include <linux/syscalls.h>
#include <linux/time_namespace.h>
#include <vdso/datapage.h>
@@ -349,25 +348,6 @@ static struct page ** __init vdso_setup_pages(void *start, void *end)
static int __init vdso_init(void)
{
#ifdef CONFIG_PPC64
- /*
- * Fill up the "systemcfg" stuff for backward compatibility
- */
- strcpy((char *)vdso_data->eye_catcher, "SYSTEMCFG:PPC64");
- vdso_data->version.major = SYSTEMCFG_MAJOR;
- vdso_data->version.minor = SYSTEMCFG_MINOR;
- vdso_data->processor = mfspr(SPRN_PVR);
- /*
- * Fake the old platform number for pSeries and add
- * in LPAR bit if necessary
- */
- vdso_data->platform = 0x100;
- if (firmware_has_feature(FW_FEATURE_LPAR))
- vdso_data->platform |= 1;
- vdso_data->physicalMemorySize = memblock_phys_mem_size();
- vdso_data->dcache_size = ppc64_caches.l1d.size;
- vdso_data->dcache_line_size = ppc64_caches.l1d.line_size;
- vdso_data->icache_size = ppc64_caches.l1i.size;
- vdso_data->icache_line_size = ppc64_caches.l1i.line_size;
vdso_data->dcache_block_size = ppc64_caches.l1d.block_size;
vdso_data->icache_block_size = ppc64_caches.l1i.block_size;
vdso_data->dcache_log_block_size = ppc64_caches.l1d.log_block_size;
diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index 8f14f0581a21b131411eedcccec5c6775a0353fe..672209428b98459ef0a5595c0ec7128a5c5f17a2 100644
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -136,7 +136,9 @@ static int pnv_smp_cpu_disable(void)
* the generic fixup_irqs. --BenH.
*/
set_cpu_online(cpu, false);
- vdso_data->processorCount--;
+#ifdef CONFIG_PPC64_PROC_SYSTEMCFG
+ systemcfg->processorCount--;
+#endif
if (cpu == boot_cpuid)
boot_cpuid = cpumask_any(cpu_online_mask);
if (xive_enabled())
diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 6838a0fcda296b1b03fbe7d1bfdcee138343b862..7b80d35d045dc9d947c0b512a58a82ef7398150d 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
@@ -83,7 +83,9 @@ static int pseries_cpu_disable(void)
int cpu = smp_processor_id();

set_cpu_online(cpu, false);
- vdso_data->processorCount--;
+#ifdef CONFIG_PPC64_PROC_SYSTEMCFG
+ systemcfg->processorCount--;
+#endif

/*fix boot_cpuid here*/
if (cpu == boot_cpuid)

--
2.47.0

Next message: Christoph Hellwig: "Re: [PATCH] asm-generic: provide generic page_to_phys and phys_to_page implementations"
Previous message: Thomas Weißschuh: "[PATCH 27/28] powerpc: Split systemcfg struct definitions out from vdso"
In reply to: Thomas Weißschuh: "[PATCH 27/28] powerpc: Split systemcfg struct definitions out from vdso"
Next in thread: Thomas Weißschuh: "[PATCH 14/28] x86: vdso: Allocate vvar page from C code"
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