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SubjectRe: [PATCH] parisc: fix module loading failure of large kernel modules (take 4)


On Wed, 31 Dec 2008, Linus Torvalds wrote:
>
> I guess I could make a sparse rule for this, but nobody seems to run or
> care about sparse anyway. Sad.

Ho humm. Looks like a sparse rule might be in order. These are just from
my (smallish) personal config. I haven't checked them all, but I did check
the first two, and yes, sparse did get it right.

init/main.c:548:24: warning: Calling weak function 'smp_setup_processor_id' in file scope
init/main.c:674:24: warning: Calling weak function 'thread_info_cache_init' in file scope
arch/x86/kernel/e820.c:1364:38: warning: Calling weak function 'machine_specific_memory_setup' in file scope
arch/x86/kernel/e820.c:1371:20: warning: Calling weak function 'memory_setup' in file scope
arch/x86/kernel/reboot.c:386:22: warning: Calling weak function 'mach_reboot_fixups' in file scope
kernel/sched.c:7720:26: warning: Calling weak function 'arch_update_cpu_topology' in file scope
kernel/sched.c:7808:41: warning: Calling weak function 'arch_update_cpu_topology' in file scope
kernel/fork.c:229:29: warning: Calling weak function 'arch_dup_task_struct' in file scope
kernel/fork.c:1325:44: warning: Calling weak function 'idle_regs' in file scope
kernel/sched_clock.c:158:19: warning: Calling weak function 'sched_clock' in file scope
kernel/sched_clock.c:207:19: warning: Calling weak function 'sched_clock' in file scope
kernel/time/timekeeping.c:283:43: warning: Calling weak function 'read_persistent_clock' in file scope
kernel/time/timekeeping.c:318:43: warning: Calling weak function 'read_persistent_clock' in file scope
kernel/time/timekeeping.c:353:50: warning: Calling weak function 'read_persistent_clock' in file scope
mm/vmalloc.c:1645:18: warning: Calling weak function 'vmalloc_sync_all' in file scope
mm/hugetlb.c:1039:32: warning: Calling weak function 'alloc_bootmem_huge_page' in file scope
mm/sparse.c:448:29: warning: Calling weak function 'vmemmap_populate_print_last' in file scope
fs/pipe.c:1069:18: warning: Calling weak function 'sys_pipe2' in file scope
fs/proc/meminfo.c:145:21: warning: Calling weak function 'arch_report_meminfo' in file scope
drivers/acpi/pci_irq.c:676:21: warning: Calling weak function 'acpi_unregister_gsi' in file scope
drivers/char/mem.c:168:23: warning: Calling weak function 'unxlate_dev_mem_ptr' in file scope
drivers/char/mem.c:172:22: warning: Calling weak function 'unxlate_dev_mem_ptr' in file scope
drivers/char/mem.c:240:23: warning: Calling weak function 'unxlate_dev_mem_ptr' in file scope
drivers/char/mem.c:246:22: warning: Calling weak function 'unxlate_dev_mem_ptr' in file scope
drivers/char/mem.c:318:12: warning: Calling weak function 'map_devmem' in file scope
drivers/char/mem.c:324:14: warning: Calling weak function 'unmap_devmem' in file scope
drivers/char/mem.c:349:35: warning: Calling weak function 'phys_mem_access_prot_allowed' in file scope
drivers/char/mem.c:365:15: warning: Calling weak function 'unmap_devmem' in file scope
drivers/pci/probe.c:1159:36: warning: Calling weak function 'set_pci_bus_resources_arch_default' in file scope
drivers/pci/pci.c:1015:24: warning: Calling weak function 'pcibios_disable_device' in file scope
drivers/pci/pci.c:1043:37: warning: Calling weak function 'pcibios_set_pcie_reset_state' in file scope
drivers/pci/pci-sysfs.c:897:39: warning: Calling weak function 'pcibios_add_platform_entries' in file scope
drivers/pci/msi.c:49:27: warning: Calling weak function 'arch_setup_msi_irq' in file scope
drivers/pci/msi.c:69:25: warning: Calling weak function 'arch_teardown_msi_irq' in file scope
drivers/pci/msi.c:421:27: warning: Calling weak function 'arch_setup_msi_irqs' in file scope
drivers/pci/msi.c:492:27: warning: Calling weak function 'arch_setup_msi_irqs' in file scope
drivers/pci/msi.c:562:29: warning: Calling weak function 'arch_msi_check_device' in file scope
drivers/pci/msi.c:654:24: warning: Calling weak function 'arch_teardown_msi_irqs' in file scope
lib/swiotlb.c:141:28: warning: Calling weak function 'swiotlb_phys_to_bus' in file scope
lib/swiotlb.c:146:41: warning: Calling weak function 'swiotlb_bus_to_phys' in file scope
lib/swiotlb.c:156:28: warning: Calling weak function 'swiotlb_phys_to_bus' in file scope
lib/swiotlb.c:167:30: warning: Calling weak function 'swiotlb_phys_to_bus' in file scope
lib/swiotlb.c:168:28: warning: Calling weak function 'swiotlb_phys_to_bus' in file scope
lib/swiotlb.c:204:35: warning: Calling weak function 'swiotlb_alloc_boot' in file scope
lib/swiotlb.c:260:31: warning: Calling weak function 'swiotlb_alloc' in file scope
lib/swiotlb.c:336:58: warning: Calling weak function 'swiotlb_arch_range_needs_mapping' in file scope
lib/swiotlb.c:336:58: warning: Calling weak function 'swiotlb_arch_range_needs_mapping' in file scope

I bet there are others that I don't see just because I don't compile the
code.

The appended trial sparse diff is against sparse -git as of a couple of
days ago if anybody wants to run it themselves.

The _logical_ fix would be to add "noinline" to the definition of
"__weak", but that's reported not to help. I think the bug may be in the
assembler that pre-links the call if it sees it in file scope. Or maybe
gcc doesn't honor noinline for empty functions. Whatever.

Regardless, it's a damn pain.

Linus

---
evaluate.c | 7 +++++++
parse.c | 7 ++++---
symbol.h | 3 ++-
3 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/evaluate.c b/evaluate.c
index f976645..0ae6c93 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -2744,6 +2744,13 @@ static int evaluate_symbol_call(struct expression *expr)
if (ctype->op && ctype->op->evaluate)
return ctype->op->evaluate(expr);

+ if (ctype->ctype.modifiers & MOD_WEAK) {
+ struct symbol *fn = ctype->ctype.base_type;
+
+ if (fn->stmt || fn->inline_stmt)
+ warning(expr->pos, "Calling weak function '%s' in file scope", show_ident(ctype->ident));
+ }
+
if (ctype->ctype.modifiers & MOD_INLINE) {
int ret;
struct symbol *curr = current_fn;
diff --git a/parse.c b/parse.c
index eb31871..1ea497f 100644
--- a/parse.c
+++ b/parse.c
@@ -289,6 +289,9 @@ static struct init_keyword {
{ "word", NS_KEYWORD, MOD_LONG, .op = &mode_spec_op },
{ "__word__", NS_KEYWORD, MOD_LONG, .op = &mode_spec_op },

+ { "weak", NS_KEYWORD, MOD_WEAK, .op = &attr_mod_op },
+ { "__weak__", NS_KEYWORD, MOD_WEAK, .op = &attr_mod_op },
+
/* Ignored attributes */
{ "nothrow", NS_KEYWORD, .op = &ignore_attr_op },
{ "__nothrow", NS_KEYWORD, .op = &ignore_attr_op },
@@ -317,8 +320,6 @@ static struct init_keyword {
{ "__sentinel__", NS_KEYWORD, .op = &ignore_attr_op },
{ "regparm", NS_KEYWORD, .op = &ignore_attr_op },
{ "__regparm__", NS_KEYWORD, .op = &ignore_attr_op },
- { "weak", NS_KEYWORD, .op = &ignore_attr_op },
- { "__weak__", NS_KEYWORD, .op = &ignore_attr_op },
{ "alias", NS_KEYWORD, .op = &ignore_attr_op },
{ "__alias__", NS_KEYWORD, .op = &ignore_attr_op },
{ "pure", NS_KEYWORD, .op = &ignore_attr_op },
@@ -1582,7 +1583,7 @@ static struct statement *start_function(struct symbol *sym)
start_function_scope();
ret = alloc_symbol(sym->pos, SYM_NODE);
ret->ctype = sym->ctype.base_type->ctype;
- ret->ctype.modifiers &= ~(MOD_STORAGE | MOD_CONST | MOD_VOLATILE | MOD_INLINE | MOD_ADDRESSABLE | MOD_NOCAST | MOD_NODEREF | MOD_ACCESSED | MOD_TOPLEVEL);
+ ret->ctype.modifiers &= ~(MOD_STORAGE | MOD_CONST | MOD_VOLATILE | MOD_INLINE | MOD_ADDRESSABLE | MOD_NOCAST | MOD_NODEREF | MOD_ACCESSED | MOD_TOPLEVEL | MOD_WEAK);
ret->ctype.modifiers |= (MOD_AUTO | MOD_REGISTER);
bind_symbol(ret, &return_ident, NS_ITERATOR);
stmt->ret = ret;
diff --git a/symbol.h b/symbol.h
index c4d7f28..b3fcccd 100644
--- a/symbol.h
+++ b/symbol.h
@@ -185,6 +185,7 @@ struct symbol {
#define MOD_LONGLONG 0x0800

#define MOD_TYPEDEF 0x1000
+#define MOD_WEAK 0x2000

#define MOD_INLINE 0x40000
#define MOD_ADDRESSABLE 0x80000
@@ -205,7 +206,7 @@ struct symbol {
#define MOD_BITWISE 0x80000000

#define MOD_NONLOCAL (MOD_EXTERN | MOD_TOPLEVEL)
-#define MOD_STORAGE (MOD_AUTO | MOD_REGISTER | MOD_STATIC | MOD_EXTERN | MOD_INLINE | MOD_TOPLEVEL | MOD_FORCE)
+#define MOD_STORAGE (MOD_AUTO | MOD_REGISTER | MOD_STATIC | MOD_EXTERN | MOD_INLINE | MOD_TOPLEVEL | MOD_FORCE | MOD_WEAK)
#define MOD_SIGNEDNESS (MOD_SIGNED | MOD_UNSIGNED | MOD_EXPLICITLY_SIGNED)
#define MOD_SPECIFIER (MOD_CHAR | MOD_SHORT | MOD_LONG | MOD_LONGLONG | MOD_SIGNEDNESS)
#define MOD_SIZE (MOD_CHAR | MOD_SHORT | MOD_LONG | MOD_LONGLONG)

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