[RFC PATCH 40/47] mm: asi: support for static percpu DEFINE_PER_CPU*_ASI

Junaid Shahid
2022-02-23T05:28:13Z

From: Ofir Weisse <oweisse@google.com>

Implemented the following PERCPU static declarations:

- DECLARE/DEFINE_PER_CPU_ASI_NOT_SENSITIVE
- DECLARE/DEFINE_PER_CPU_SHARED_ALIGNED_ASI_NOT_SENSITIVE
- DECLARE/DEFINE_PER_CPU_ALIGNED_ASI_NOT_SENSITIVE
- DECLARE/DEFINE_PER_CPU_PAGE_ALIGNED_ASI_NOT_SENSITIVE

These definitions are also supported in dynamic modules.
To support percpu variables in dynamic modules, we're creating an ASI
pcpu reserved chunk. The reserved size PERCPU_MODULE_RESERVE is now
split between the normal reserved chunk and the ASI one.

Signed-off-by: Ofir Weisse <oweisse@google.com>

---
arch/x86/mm/asi.c | 39 +++++++-
include/asm-generic/percpu.h | 6 ++
include/asm-generic/vmlinux.lds.h | 5 +
include/linux/module.h | 6 ++
include/linux/percpu-defs.h | 39 ++++++++
include/linux/percpu.h | 8 +-
kernel/module-internal.h | 1 +
kernel/module.c | 154 ++++++++++++++++++++++++++----
mm/percpu.c | 134 ++++++++++++++++++++++----
9 files changed, 356 insertions(+), 36 deletions(-)

diff --git a/arch/x86/mm/asi.c b/arch/x86/mm/asi.c
index 6c14aa1fc4aa..ba373b461855 100644
--- a/arch/x86/mm/asi.c
+++ b/arch/x86/mm/asi.c
@@ -309,6 +309,32 @@ static int __init set_asi_param(char *str)
}
early_param("asi", set_asi_param);

+static int asi_map_percpu(struct asi *asi, void *percpu_addr, size_t len)
+{
+ int cpu, err;
+ void *ptr;
+
+ for_each_possible_cpu(cpu) {
+ ptr = per_cpu_ptr(percpu_addr, cpu);
+ err = asi_map(asi, ptr, len);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static void asi_unmap_percpu(struct asi *asi, void *percpu_addr, size_t len)
+{
+ int cpu;
+ void *ptr;
+
+ for_each_possible_cpu(cpu) {
+ ptr = per_cpu_ptr(percpu_addr, cpu);
+ asi_unmap(asi, ptr, len, true);
+ }
+}
+
/* asi_load_module() is called from layout_and_allocate() in kernel/module.c
* We map the module and its data in init_mm.asi_pgd[0].
*/
@@ -347,7 +373,13 @@ int asi_load_module(struct module* module)
if (err)
return err;

- return 0;
+ err = asi_map_percpu(ASI_GLOBAL_NONSENSITIVE,
+ module->percpu_asi,
+ module->percpu_asi_size );
+ if (err)
+ return err;
+
+ return 0;
}
EXPORT_SYMBOL_GPL(asi_load_module);

@@ -372,6 +404,9 @@ void asi_unload_module(struct module* module)
module->core_layout.once_section_offset,
module->core_layout.once_section_size, true);

+ asi_unmap_percpu(ASI_GLOBAL_NONSENSITIVE, module->percpu_asi,
+ module->percpu_asi_size);
+
}

static int __init asi_global_init(void)
@@ -399,6 +434,8 @@ static int __init asi_global_init(void)

static_branch_enable(&asi_local_map_initialized);

+ pcpu_map_asi_reserved_chunk();
+
return 0;
}
subsys_initcall(asi_global_init)
diff --git a/include/asm-generic/percpu.h b/include/asm-generic/percpu.h
index 6432a7fade91..40001b74114f 100644
--- a/include/asm-generic/percpu.h
+++ b/include/asm-generic/percpu.h
@@ -50,6 +50,12 @@ extern void setup_per_cpu_areas(void);

#endif /* SMP */

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+void __init pcpu_map_asi_reserved_chunk(void);
+#else
+static inline void pcpu_map_asi_reserved_chunk(void) {}
+#endif
+
#ifndef PER_CPU_BASE_SECTION
#ifdef CONFIG_SMP
#define PER_CPU_BASE_SECTION ".data..percpu"
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index c769d939c15f..0a931aedc285 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -1080,6 +1080,11 @@
. = ALIGN(cacheline); \
*(.data..percpu) \
*(.data..percpu..shared_aligned) \
+ . = ALIGN(PAGE_SIZE); \
+ __per_cpu_asi_start = .; \
+ *(.data..percpu..asi_non_sensitive) \
+ . = ALIGN(PAGE_SIZE); \
+ __per_cpu_asi_end = .; \
PERCPU_DECRYPTED_SECTION \
__per_cpu_end = .;

diff --git a/include/linux/module.h b/include/linux/module.h
index 82267a95f936..d4d020bae171 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -463,6 +463,12 @@ struct module {
/* Per-cpu data. */
void __percpu *percpu;
unsigned int percpu_size;
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ /* Per-cpu data for ASI */
+ void __percpu *percpu_asi;
+ unsigned int percpu_asi_size;
+#endif /* CONFIG_ADDRESS_SPACE_ISOLATION */
+
#endif
void *noinstr_text_start;
unsigned int noinstr_text_size;
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index af1071535de8..5d9fdc93e0fa 100644
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -170,6 +170,45 @@

#define DEFINE_PER_CPU_READ_MOSTLY(type, name) \
DEFINE_PER_CPU_SECTION(type, name, "..read_mostly")
+/*
+ * Declaration/definition used for per-CPU variables which for the sake for
+ * address space isolation (ASI) are deemed not sensitive
+ */
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+#define ASI_PERCPU_SECTION "..asi_non_sensitive"
+#else
+#define ASI_PERCPU_SECTION ""
+#endif
+
+#define DECLARE_PER_CPU_ASI_NOT_SENSITIVE(type, name) \
+ DECLARE_PER_CPU_SECTION(type, name, ASI_PERCPU_SECTION)
+
+#define DECLARE_PER_CPU_SHARED_ALIGNED_ASI_NOT_SENSITIVE(type, name) \
+ DECLARE_PER_CPU_SECTION(type, name, ASI_PERCPU_SECTION) \
+ ____cacheline_aligned_in_smp
+
+#define DECLARE_PER_CPU_ALIGNED_ASI_NOT_SENSITIVE(type, name) \
+ DECLARE_PER_CPU_SECTION(type, name, ASI_PERCPU_SECTION) \
+ ____cacheline_aligned
+
+#define DECLARE_PER_CPU_PAGE_ALIGNED_ASI_NOT_SENSITIVE(type, name) \
+ DECLARE_PER_CPU_SECTION(type, name, ASI_PERCPU_SECTION) \
+ __aligned(PAGE_SIZE)
+
+#define DEFINE_PER_CPU_ASI_NOT_SENSITIVE(type, name) \
+ DEFINE_PER_CPU_SECTION(type, name, ASI_PERCPU_SECTION)
+
+#define DEFINE_PER_CPU_SHARED_ALIGNED_ASI_NOT_SENSITIVE(type, name) \
+ DEFINE_PER_CPU_SECTION(type, name, ASI_PERCPU_SECTION) \
+ ____cacheline_aligned_in_smp
+
+#define DEFINE_PER_CPU_ALIGNED_ASI_NOT_SENSITIVE(type, name) \
+ DEFINE_PER_CPU_SECTION(type, name, ASI_PERCPU_SECTION) \
+ ____cacheline_aligned
+
+#define DEFINE_PER_CPU_PAGE_ALIGNED_ASI_NOT_SENSITIVE(type, name) \
+ DEFINE_PER_CPU_SECTION(type, name, ASI_PERCPU_SECTION) \
+ __aligned(PAGE_SIZE)

/*
* Declaration/definition used for per-CPU variables that should be accessed
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index ae4004e7957e..a2cc4c32cabd 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -13,7 +13,8 @@

/* enough to cover all DEFINE_PER_CPUs in modules */
#ifdef CONFIG_MODULES
-#define PERCPU_MODULE_RESERVE (8 << 10)
+/* #define PERCPU_MODULE_RESERVE (8 << 10) */
+#define PERCPU_MODULE_RESERVE (16 << 10)
#else
#define PERCPU_MODULE_RESERVE 0
#endif
@@ -123,6 +124,11 @@ extern int __init pcpu_page_first_chunk(size_t reserved_size,
#endif

extern void __percpu *__alloc_reserved_percpu(size_t size, size_t align) __alloc_size(1);
+
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+extern void __percpu *__alloc_reserved_percpu_asi(size_t size, size_t align);
+#endif
+
extern bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr);
extern bool is_kernel_percpu_address(unsigned long addr);

diff --git a/kernel/module-internal.h b/kernel/module-internal.h
index 33783abc377b..44c05ae06b2c 100644
--- a/kernel/module-internal.h
+++ b/kernel/module-internal.h
@@ -25,6 +25,7 @@ struct load_info {
#endif
struct {
unsigned int sym, str, mod, vers, info, pcpu;
+ unsigned int pcpu_asi;
} index;
};

diff --git a/kernel/module.c b/kernel/module.c
index d363b8a0ee24..0048b7843903 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -587,6 +587,13 @@ static inline void __percpu *mod_percpu(struct module *mod)
return mod->percpu;
}

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+static inline void __percpu *mod_percpu_asi(struct module *mod)
+{
+ return mod->percpu_asi;
+}
+#endif
+
static int percpu_modalloc(struct module *mod, struct load_info *info)
{
Elf_Shdr *pcpusec = &info->sechdrs[info->index.pcpu];
@@ -611,9 +618,34 @@ static int percpu_modalloc(struct module *mod, struct load_info *info)
return 0;
}

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+static int percpu_asi_modalloc(struct module *mod, struct load_info *info)
+{
+ Elf_Shdr *pcpusec = &info->sechdrs[info->index.pcpu_asi];
+ unsigned long align = pcpusec->sh_addralign;
+
+ if ( !pcpusec->sh_size)
+ return 0;
+
+ mod->percpu_asi = __alloc_reserved_percpu_asi(pcpusec->sh_size, align);
+ if (!mod->percpu_asi) {
+ pr_warn("%s: Could not allocate %lu bytes percpu data\n",
+ mod->name, (unsigned long)pcpusec->sh_size);
+ return -ENOMEM;
+ }
+ mod->percpu_asi_size = pcpusec->sh_size;
+
+ return 0;
+}
+#endif
+
static void percpu_modfree(struct module *mod)
{
free_percpu(mod->percpu);
+
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ free_percpu(mod->percpu_asi);
+#endif
}

static unsigned int find_pcpusec(struct load_info *info)
@@ -621,6 +653,13 @@ static unsigned int find_pcpusec(struct load_info *info)
return find_sec(info, ".data..percpu");
}

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+static unsigned int find_pcpusec_asi(struct load_info *info)
+{
+ return find_sec(info, ".data..percpu" ASI_PERCPU_SECTION );
+}
+#endif
+
static void percpu_modcopy(struct module *mod,
const void *from, unsigned long size)
{
@@ -630,6 +669,39 @@ static void percpu_modcopy(struct module *mod,
memcpy(per_cpu_ptr(mod->percpu, cpu), from, size);
}

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+static void percpu_asi_modcopy(struct module *mod,
+ const void *from, unsigned long size)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ memcpy(per_cpu_ptr(mod->percpu_asi, cpu), from, size);
+}
+#endif
+
+bool __is_module_percpu_address_helper(unsigned long addr,
+ unsigned long *can_addr,
+ unsigned int cpu,
+ void* percpu_start,
+ unsigned int percpu_size)
+{
+ void *start = per_cpu_ptr(percpu_start, cpu);
+ void *va = (void *)addr;
+
+ if (va >= start && va < start + percpu_size) {
+ if (can_addr) {
+ *can_addr = (unsigned long) (va - start);
+ *can_addr += (unsigned long)
+ per_cpu_ptr(percpu_start,
+ get_boot_cpu_id());
+ }
+ return true;
+ }
+
+ return false;
+}
+
bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
{
struct module *mod;
@@ -640,22 +712,34 @@ bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
list_for_each_entry_rcu(mod, &modules, list) {
if (mod->state == MODULE_STATE_UNFORMED)
continue;
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ if (!mod->percpu_size && !mod->percpu_asi_size)
+ continue;
+#else
if (!mod->percpu_size)
continue;
+#endif
for_each_possible_cpu(cpu) {
- void *start = per_cpu_ptr(mod->percpu, cpu);
- void *va = (void *)addr;
-
- if (va >= start && va < start + mod->percpu_size) {
- if (can_addr) {
- *can_addr = (unsigned long) (va - start);
- *can_addr += (unsigned long)
- per_cpu_ptr(mod->percpu,
- get_boot_cpu_id());
- }
+ if (__is_module_percpu_address_helper(addr,
+ can_addr,
+ cpu,
+ mod->percpu,
+ mod->percpu_size)) {
preempt_enable();
return true;
- }
+ }
+
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ if (__is_module_percpu_address_helper(
+ addr,
+ can_addr,
+ cpu,
+ mod->percpu_asi,
+ mod->percpu_asi_size)) {
+ preempt_enable();
+ return true;
+ }
+#endif
}
}

@@ -2344,6 +2428,10 @@ static int simplify_symbols(struct module *mod, const struct load_info *info)
/* Divert to percpu allocation if a percpu var. */
if (sym[i].st_shndx == info->index.pcpu)
secbase = (unsigned long)mod_percpu(mod);
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ else if (sym[i].st_shndx == info->index.pcpu_asi)
+ secbase = (unsigned long)mod_percpu_asi(mod);
+#endif
else
secbase = info->sechdrs[sym[i].st_shndx].sh_addr;
sym[i].st_value += secbase;
@@ -2664,6 +2752,10 @@ static char elf_type(const Elf_Sym *sym, const struct load_info *info)
return 'U';
if (sym->st_shndx == SHN_ABS || sym->st_shndx == info->index.pcpu)
return 'a';
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ if (sym->st_shndx == info->index.pcpu_asi)
+ return 'a';
+#endif
if (sym->st_shndx >= SHN_LORESERVE)
return '?';
if (sechdrs[sym->st_shndx].sh_flags & SHF_EXECINSTR)
@@ -2691,7 +2783,8 @@ static char elf_type(const Elf_Sym *sym, const struct load_info *info)
}

static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs,
- unsigned int shnum, unsigned int pcpundx)
+ unsigned int shnum, unsigned int pcpundx,
+ unsigned pcpu_asi_ndx)
{
const Elf_Shdr *sec;

@@ -2701,7 +2794,7 @@ static bool is_core_symbol(const Elf_Sym *src, const Elf_Shdr *sechdrs,
return false;

#ifdef CONFIG_KALLSYMS_ALL
- if (src->st_shndx == pcpundx)
+ if (src->st_shndx == pcpundx || src->st_shndx == pcpu_asi_ndx )
return true;
#endif

@@ -2743,7 +2836,7 @@ static void layout_symtab(struct module *mod, struct load_info *info)
for (ndst = i = 0; i < nsrc; i++) {
if (i == 0 || is_livepatch_module(mod) ||
is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum,
- info->index.pcpu)) {
+ info->index.pcpu, info->index.pcpu_asi)) {
strtab_size += strlen(&info->strtab[src[i].st_name])+1;
ndst++;
}
@@ -2807,7 +2900,7 @@ static void add_kallsyms(struct module *mod, const struct load_info *info)
mod->kallsyms->typetab[i] = elf_type(src + i, info);
if (i == 0 || is_livepatch_module(mod) ||
is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum,
- info->index.pcpu)) {
+ info->index.pcpu, info->index.pcpu_asi)) {
mod->core_kallsyms.typetab[ndst] =
mod->kallsyms->typetab[i];
dst[ndst] = src[i];
@@ -3289,6 +3382,12 @@ static int setup_load_info(struct load_info *info, int flags)

info->index.pcpu = find_pcpusec(info);

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ info->index.pcpu_asi = find_pcpusec_asi(info);
+#else
+ info->index.pcpu_asi = 0;
+#endif
+
return 0;
}

@@ -3629,6 +3728,12 @@ static struct module *layout_and_allocate(struct load_info *info, int flags)
/* We will do a special allocation for per-cpu sections later. */
info->sechdrs[info->index.pcpu].sh_flags &= ~(unsigned long)SHF_ALLOC;

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ if (info->index.pcpu_asi)
+ info->sechdrs[info->index.pcpu_asi].sh_flags &=
+ ~(unsigned long)SHF_ALLOC;
+#endif
+
/*
* Mark ro_after_init section with SHF_RO_AFTER_INIT so that
* layout_sections() can put it in the right place.
@@ -3700,6 +3805,14 @@ static int post_relocation(struct module *mod, const struct load_info *info)
percpu_modcopy(mod, (void *)info->sechdrs[info->index.pcpu].sh_addr,
info->sechdrs[info->index.pcpu].sh_size);

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ /* Copy relocated percpu ASI area over. */
+ percpu_asi_modcopy(
+ mod,
+ (void *)info->sechdrs[info->index.pcpu_asi].sh_addr,
+ info->sechdrs[info->index.pcpu_asi].sh_size);
+#endif
+
/* Setup kallsyms-specific fields. */
add_kallsyms(mod, info);

@@ -4094,6 +4207,11 @@ static int load_module(struct load_info *info, const char __user *uargs,
err = percpu_modalloc(mod, info);
if (err)
goto unlink_mod;
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ err = percpu_asi_modalloc(mod, info);
+ if (err)
+ goto unlink_mod;
+#endif

/* Now module is in final location, initialize linked lists, etc. */
err = module_unload_init(mod);
@@ -4183,7 +4301,11 @@ static int load_module(struct load_info *info, const char __user *uargs,
/* Get rid of temporary copy. */
free_copy(info);

- asi_load_module(mod);
+ err = asi_load_module(mod);
+ /* If the ASI loading failed, it doesn't necessarily mean that the
+ * module loading failed. We print an error and move on. */
+ if (err)
+ pr_err("ASI: failed loading module %s", mod->name);

/* Done! */
trace_module_load(mod);
diff --git a/mm/percpu.c b/mm/percpu.c
index beaca5adf9d4..3665a5ea71ec 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -169,6 +169,10 @@ struct pcpu_chunk *pcpu_first_chunk __ro_after_init;
*/
struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init;

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+struct pcpu_chunk *pcpu_reserved_nonsensitive_chunk __ro_after_init;
+#endif
+
DEFINE_SPINLOCK(pcpu_lock); /* all internal data structures */
static DEFINE_MUTEX(pcpu_alloc_mutex); /* chunk create/destroy, [de]pop, map ext */

@@ -1621,6 +1625,11 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
if (pcpu_addr_in_chunk(pcpu_first_chunk, addr))
return pcpu_first_chunk;

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ /* is it in the reserved ASI region? */
+ if (pcpu_addr_in_chunk(pcpu_reserved_nonsensitive_chunk, addr))
+ return pcpu_reserved_nonsensitive_chunk;
+#endif
/* is it in the reserved region? */
if (pcpu_addr_in_chunk(pcpu_reserved_chunk, addr))
return pcpu_reserved_chunk;
@@ -1805,23 +1814,37 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,

spin_lock_irqsave(&pcpu_lock, flags);

+#define TRY_ALLOC_FROM_CHUNK(source_chunk, chunk_name) \
+do { \
+ if (!source_chunk) { \
+ err = chunk_name " chunk not allocated"; \
+ goto fail_unlock; \
+ } \
+ chunk = source_chunk; \
+ \
+ off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic); \
+ if (off < 0) { \
+ err = "alloc from " chunk_name " chunk failed"; \
+ goto fail_unlock; \
+ } \
+ \
+ off = pcpu_alloc_area(chunk, bits, bit_align, off); \
+ if (off >= 0) \
+ goto area_found; \
+ \
+ err = "alloc from " chunk_name " chunk failed"; \
+ goto fail_unlock; \
+} while(0)
+
/* serve reserved allocations from the reserved chunk if available */
- if (reserved && pcpu_reserved_chunk) {
- chunk = pcpu_reserved_chunk;
-
- off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic);
- if (off < 0) {
- err = "alloc from reserved chunk failed";
- goto fail_unlock;
- }
-
- off = pcpu_alloc_area(chunk, bits, bit_align, off);
- if (off >= 0)
- goto area_found;
-
- err = "alloc from reserved chunk failed";
- goto fail_unlock;
- }
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ if (reserved && (gfp & __GFP_GLOBAL_NONSENSITIVE))
+ TRY_ALLOC_FROM_CHUNK(pcpu_reserved_nonsensitive_chunk,
+ "reserverved ASI");
+ else
+#endif
+ if (reserved && pcpu_reserved_chunk)
+ TRY_ALLOC_FROM_CHUNK(pcpu_reserved_chunk, "reserved");

restart:
/* search through normal chunks */
@@ -1998,6 +2021,14 @@ void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
return pcpu_alloc(size, align, true, GFP_KERNEL);
}

+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+void __percpu *__alloc_reserved_percpu_asi(size_t size, size_t align)
+{
+ return pcpu_alloc(size, align, true,
+ GFP_KERNEL | __GFP_GLOBAL_NONSENSITIVE);
+}
+#endif
+
/**
* pcpu_balance_free - manage the amount of free chunks
* @empty_only: free chunks only if there are no populated pages
@@ -2838,15 +2869,46 @@ void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
* the dynamic region.
*/
tmp_addr = (unsigned long)base_addr + static_size;
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ /* If ASI is used, split the reserved size between the nonsensitive
+ * chunk and the normal chunk evenly. */
+ map_size = (ai->reserved_size / 2) ?: dyn_size;
+#else
map_size = ai->reserved_size ?: dyn_size;
+#endif
chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);

/* init dynamic chunk if necessary */
if (ai->reserved_size) {
- pcpu_reserved_chunk = chunk;
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+ /* TODO: check if ASI was enabled via boot param or static branch */
+ /* We allocated pcpu_reserved_nonsensitive_chunk only if
+ * pcpu_reserved_chunk is used as well. */
+ pcpu_reserved_nonsensitive_chunk = chunk;
+ pcpu_reserved_nonsensitive_chunk->is_asi_nonsensitive = true;

+ /* We used the previous chunk as pcpu_reserved_nonsensitive_chunk. Now
+ * allocate pcpu_reserved_chunk */
+ tmp_addr = (unsigned long)base_addr + static_size +
+ (ai->reserved_size / 2);
+ map_size = ai->reserved_size / 2;
+ chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
+#endif
+ /* Whether ASI is enabled or disabled, the end result is the
+ * same:
+ * If ASI is enabled, tmp_addr, used for pcpu_first_chunk should
+ * be after
+ * 1. pcpu_reserved_nonsensitive_chunk AND
+ * 2. pcpu_reserved_chunk
+ * Since we split the reserve size in half, we skip in total the
+ * whole ai->reserved_size.
+ * If ASI is disabled, tmp_addr, used for pcpu_first_chunk is
+ * just after pcpu_reserved_chunk */
tmp_addr = (unsigned long)base_addr + static_size +
ai->reserved_size;
+
+ pcpu_reserved_chunk = chunk;
+
map_size = dyn_size;
chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
}
@@ -3129,7 +3191,6 @@ int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
cpu_distance_fn);
if (IS_ERR(ai))
return PTR_ERR(ai);
-
size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));

@@ -3460,3 +3521,40 @@ static int __init percpu_enable_async(void)
return 0;
}
subsys_initcall(percpu_enable_async);
+
+#ifdef CONFIG_ADDRESS_SPACE_ISOLATION
+void __init pcpu_map_asi_reserved_chunk(void)
+{
+ void *start_addr, *end_addr;
+ unsigned long map_start_addr, map_end_addr;
+ struct pcpu_chunk *chunk = pcpu_reserved_nonsensitive_chunk;
+ int err = 0;
+
+ if (!chunk)
+ return;
+
+ start_addr = chunk->base_addr + chunk->start_offset;
+ end_addr = chunk->base_addr + chunk->nr_pages * PAGE_SIZE -
+ chunk->end_offset;
+
+
+ /* No need in asi_map_percpu, since these addresses are "real". The
+ * chunk has full pages allocated, so we're not worried about leakage of
+ * data caused by start_addr-->end_addr not being page aligned. asi_map,
+ * however, will fail/crash if the addresses are not aligned. */
+ map_start_addr = (unsigned long)start_addr & PAGE_MASK;
+ map_end_addr = PAGE_ALIGN((unsigned long)end_addr);
+
+ pr_err("%s:%d mapping 0x%lx --> 0x%lx",
+ __FUNCTION__, __LINE__, map_start_addr, map_end_addr);
+ err = asi_map(ASI_GLOBAL_NONSENSITIVE,
+ (void*)map_start_addr, map_end_addr - map_start_addr);
+
+ WARN(err, "Failed mapping percpu reserved chunk into ASI");
+
+ /* If we couldn't map the chuknk into ASI, it is useless. Set the chunk
+ * to NULL, so allocations from it will fail. */
+ if (err)
+ pcpu_reserved_nonsensitive_chunk = NULL;
+}
+#endif
--
2.35.1.473.g83b2b277ed-goog