lguest: clean up some l"references .init.text" warnings

PATCH New Rusty Russell 2 participants 5 messages Mar 22, 2007 – Mar 23, 2007

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Rusty Russell

author

2007-03-22 02:57 UTC #0 lore raw

PATCH 1/1 lguest: clean up some l"references .init.text" warnings

Thanks to Andrew for pointing these out.

This patch moves the parvirtprobe section into .init.data: it's only used in very very early boot, and for similar reasons, puts lguest_maybe_init and lguest_memory_setup in init.text.

As well as fixing some warnings, this frees up a tiny bit more memory.

Signed-off-by Rusty Russell <[email protected]>

arch/i386/kernel/vmlinux.lds.S +6 -7

diff -r ecec388180b2 arch/i386/kernel/vmlinux.lds.S
@@ -81,12 +81,6 @@ SECTIONS
 	CONSTRUCTORS
 	} :data
 
-  .paravirtprobe : AT(ADDR(.paravirtprobe) - LOAD_OFFSET) {
-  	__start_paravirtprobe = .;
-	*(.paravirtprobe)
-  	__stop_paravirtprobe = .;
-  }
-
   . = ALIGN(4096);
   .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
   	__nosave_begin = .;

@@ -151,7 +145,12 @@ SECTIONS
 	*(.init.text)
 	_einittext = .;
   }
-  .init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { *(.init.data) }
+  .init.data : AT(ADDR(.init.data) - LOAD_OFFSET) {
+	*(.init.data)
+  	__start_paravirtprobe = .;
+	*(.paravirtprobe)
+  	__stop_paravirtprobe = .;
+  }
   . = ALIGN(16);
   .init.setup : AT(ADDR(.init.setup) - LOAD_OFFSET) {
   	__setup_start = .;

arch/i386/lguest/lguest.c +3 -2

diff -r ecec388180b2 arch/i386/lguest/lguest.c
@@ -136,7 +136,7 @@ static struct notifier_block paniced = {
 	.notifier_call = lguest_panic
 };
 
-static char *lguest_memory_setup(void)
+static __init char *lguest_memory_setup(void)
 {
 	/* We do this here because lockcheck barfs if before start_kernel */
 	atomic_notifier_chain_register(&panic_notifier_list, &paniced);

@@ -549,7 +549,8 @@ static __attribute_used__ __init void lg
 	start_kernel();
 }
 
-asm("lguest_maybe_init:\n"
+asm(".section .init.text\n"
+    "lguest_maybe_init:\n"
     "	cmpl $"__stringify(LGUEST_MAGIC_EBP)", %ebp\n"
     "	jne 1f\n"
     "	cmpl $"__stringify(LGUEST_MAGIC_EDI)", %edi\n"

Rusty Russell

author

2007-03-22 10:09 UTC #1 lore raw

PATCH 1/1 lguest: clean rest of linkage warnings (bar one)

My previous warning fix broke lguest if your text size wasn't correct to make the __start_paravirtprobe aligned correctly. Put the separate paravirtprobe section back, but inside the init section so it gets discarded.

It also fixes the remaining warnings, except one. The code in modpost.c which needs to be taught that it's legal to link from .paravirtprobe to .init.text is horrible, and I'm pretty sure I'd just make it worse.

Signed-off-by Rusty Russell <[email protected]>

arch/i386/kernel/vmlinux.lds.S +6 -6

diff -r a38b5b461807 arch/i386/kernel/vmlinux.lds.S
@@ -145,12 +145,7 @@ SECTIONS
 	*(.init.text)
 	_einittext = .;
   }
-  .init.data : AT(ADDR(.init.data) - LOAD_OFFSET) {
-	*(.init.data)
-  	__start_paravirtprobe = .;
-	*(.paravirtprobe)
-  	__stop_paravirtprobe = .;
-  }
+  .init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { *(.init.data) }
   . = ALIGN(16);
   .init.setup : AT(ADDR(.init.setup) - LOAD_OFFSET) {
   	__setup_start = .;

@@ -178,6 +173,11 @@ SECTIONS
 	*(.altinstr_replacement)
   }
   . = ALIGN(4);
+  .paravirtprobe : AT(ADDR(.paravirtprobe) - LOAD_OFFSET) {
+ 	__start_paravirtprobe = .;
+	*(.paravirtprobe)
+  	__stop_paravirtprobe = .;
+  }
   .parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) {
   	__start_parainstructions = .;
 	*(.parainstructions)

arch/i386/lguest/core.c +1 -1

diff -r a38b5b461807 arch/i386/lguest/core.c
@@ -131,7 +131,7 @@ free_some_pages:
 	return err;
 }
 
-static __exit void unmap_hypervisor(void)
+static void unmap_hypervisor(void)
 {
 	unsigned int i;

arch/i386/lguest/lg.h +1 -1

diff -r a38b5b461807 arch/i386/lguest/lg.h
@@ -38,7 +38,7 @@ struct lguest_regs
 	u32 ss;
 };
 
-__exit void free_pagetables(void);
+void free_pagetables(void);
 __init int init_pagetables(struct page **hype_page, int pages);
 
 /* Full 4G segment descriptors, suitable for CS and DS. */

arch/i386/lguest/lguest.c +3 -2

diff -r a38b5b461807 arch/i386/lguest/lguest.c
@@ -550,7 +550,7 @@ static __attribute_used__ __init void lg
 	start_kernel();
 }
 
-asm(".section .init.text\n"
+asm(".pushsection .init.text,\"ax\",@progbits\n"
     "lguest_maybe_init:\n"
     "	cmpl $"__stringify(LGUEST_MAGIC_EBP)", %ebp\n"
     "	jne 1f\n"

@@ -558,6 +558,7 @@ asm(".section .init.text\n"
     "	jne 1f\n"
     "	cmpl $"__stringify(LGUEST_MAGIC_ESI)", %esi\n"
     "	je lguest_init\n"
-    "1: ret");
+    "1: ret\n"
+    ".popsection");
 extern void asmlinkage lguest_maybe_init(void);
 paravirt_probe(lguest_maybe_init);

arch/i386/lguest/page_tables.c +1 -1

diff -r a38b5b461807 arch/i386/lguest/page_tables.c
@@ -381,7 +381,7 @@ __init int init_pagetables(struct page *
 	return 0;
 }
 
-__exit void free_pagetables(void)
+void free_pagetables(void)
 {
 	free_hypervisor_pte_pages();
 }

Sam Ravnborg

2007-03-22 11:45 UTC #2 lore raw

Re: [PATCH] lguest: clean rest of linkage warnings (bar one)

Quoted 9 lines · Rusty Russell

My previous warning fix broke lguest if your text size wasn't correct to make the __start_paravirtprobe aligned correctly. Put the separate paravirtprobe section back, but inside the init section so it gets discarded.
It also fixes the remaining warnings, except one. The code in modpost.c which needs to be taught that it's legal to link from .paravirtprobe to .init.text is horrible, and I'm pretty sure I'd just make it worse.

If you drop me a sample of the exact warning I will add this one too. Current kbuild.git contains a lot of fixes in this area so I refer to do so on top of that tree.

Sam

Rusty Russell

author

2007-03-23 07:25 UTC #3 lore raw

Re: [PATCH] lguest: clean rest of linkage warnings (bar one)

Quoted 9 lines · Sam Ravnborg

Quoted 4 lines · Rusty Russell
It also fixes the remaining warnings, except one. The code in modpost.c which needs to be taught that it's legal to link from .paravirtprobe to .init.text is horrible, and I'm pretty sure I'd just make it worse.
If you drop me a sample of the exact warning I will add this one too. Current kbuild.git contains a lot of fixes in this area so I refer to do so on top of that tree.

WARNING: vmlinux - Section mismatch: reference to .init.text: from .paravirtprobe between '__start_paravirtprobe' (at offset 0xc0464c7c) and '__stop_paravirtprobe'

Sam, you're always so polite and damn helpful: I'm pretty sure that violates the core tenets of Linux etiquette.

Perhaps you could work on that?
Rusty.

Sam Ravnborg

2007-03-23 19:04 UTC #4 lore raw

Re: [PATCH] lguest: clean rest of linkage warnings (bar one)

Quoted 7 lines · Rusty Russell

Quoted 6 lines · Sam Ravnborg
Quoted 4 lines · Rusty Russell
It also fixes the remaining warnings, except one. The code in modpost.c which needs to be taught that it's legal to link from .paravirtprobe to .init.text is horrible, and I'm pretty sure I'd just make it worse.

Quoted 8 lines

Quoted 3 lines
If you drop me a sample of the exact warning I will add this one too. Current kbuild.git contains a lot of fixes in this area so I refer to do so on top of that tree.
WARNING: vmlinux - Section mismatch: reference to .init.text: from .paravirtprobe between '__start_paravirtprobe' (at offset 0xc0464c7c) and '__stop_paravirtprobe'
Sam, you're always so polite and damn helpful: I'm pretty sure that violates the core tenets of Linux etiquette.

I get this strange feeling that you are planning to ask me to do much more....

Anyway I have added following path to kbuild.git.
Two small unrelated changes sneaked in (deleting a wrong part of a comment and adding an empty line)

It should apply on top of latest -mm

Sam

scripts/mod/modpost.c +14 -1

index 06a16ac..1e578fd 100644
@@ -626,7 +626,6 @@ static int strrcmp(const char *s, const char *sub)
  *   tosec   = .init.text
  *   fromsec = .text
  *   atsym = kernel_init
- *   Some symbols belong to init section but still it is ok to reference
  *
  * Pattern 7:
  *  Logos used in drivers/video/logo reside in __initdata but the

@@ -643,6 +642,13 @@ static int strrcmp(const char *s, const char *sub)
  *  The pattern is:
  *  tosec    = .init.text
  *  fromsec  = __ksymtab*
+ *
+ * Pattern 9:
+ *  Symbols contained in .paravirtprobe amy safely reference
+ *  .init.text.
+ *  The pattern is:
+ *  tosec   = .init.text
+ *  fromsec  = .paravirtprobe
  **/
 static int secref_whitelist(const char *modname, const char *tosec,
 			    const char *fromsec, const char *atsym,

@@ -720,10 +726,17 @@ static int secref_whitelist(const char *modname, const char *tosec,
 	    (strncmp(fromsec, ".text", strlen(".text")) == 0) &&
 	    (strncmp(refsymname, "logo_", strlen("logo_")) == 0))
 		return 1;
+
 	/* Check for pattern 8 */
 	if ((strcmp(tosec, ".init.text") == 0) &&
 	    (strncmp(fromsec, "__ksymtab", strlen("__ksymtab")) == 0))
 		return 1;
+
+	/* Check for pattern 9 */
+	if ((strcmp(tosec, ".init.text") == 0) &&
+	    (strcmp(fromsec, ".paravirtprobe") == 0))
+		return 1;
+
 	return 0;
 }