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modpost: Fix section warnings for ARM for many compilers

PATCH In review Tony Lindgren 4 participants 6 messages Feb 13, 2012 – Feb 14, 2012 Kbuild

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Tony Lindgren

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#0 lore raw

PATCH 1/1 modpost: Fix section warnings for ARM for many compilers

It turns out that many compilers don't show section warnings on ARM currently because handling for ARM_CALL relocs are missing from modpost.c.

Based on commit c2e26114 ([ARM] 3205/1: Handle new EABI relocations when loading kernel modules) it seems that R_ARM_PC24, R_ARM_CALL and R_ARM_JUMP24 can be handled the same way.

As modpost.c includes elf.h, we need to also consider that at least Debian libc6-dev is missing defines for both R_ARM_CALL and R_ARM_JUMP24 in /usr/include/elf.h.

So for now let's just use the numbers in modpost.c.

Cc Rusty Russell <[email protected]>
Cc Ben Hutchings <[email protected]>
Cc Anders Kaseorg <[email protected]>
Cc Greg KH <[email protected]>
Cc Russell King <[email protected]>
Signed-off-by Tony Lindgren <[email protected]>

---

Anybody got better ideas for dealing with the missing elf.h defines?

scripts/mod/modpost.c +2 -0
@@ -1505,6 +1505,8 @@ static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
 		              (elf->symtab_start + ELF_R_SYM(r->r_info));
 		break;
 	case R_ARM_PC24:
+	case 28:		/* R_ARM_CALL */
+	case 29:		/* R_ARM_JUMP24 */
 		/* From ARM ABI: ((S + A) | T) - P */
 		r->r_addend = (int)(long)(elf->hdr +
 		              sechdr->sh_offset +
#1 lore raw
Quoted 11 lines · Tony Lindgren

It turns out that many compilers don't show section warnings on ARM currently because handling for ARM_CALL relocs are missing from modpost.c.

Based on commit c2e26114 ([ARM] 3205/1: Handle new EABI relocations when loading kernel modules) it seems that R_ARM_PC24, R_ARM_CALL and R_ARM_JUMP24 can be handled the same way.

As modpost.c includes elf.h, we need to also consider that at least Debian libc6-dev is missing defines for both R_ARM_CALL and R_ARM_JUMP24 in /usr/include/elf.h.

Huh, even unstable's /usr/include/elf.h doesn't have these symbols.

Quoted 9 lines

So for now let's just use the numbers in modpost.c.

Cc Rusty Russell <[email protected]>
Cc Ben Hutchings <[email protected]>
Cc Anders Kaseorg <[email protected]>
Cc Greg KH <[email protected]>
Cc Russell King <[email protected]>
Signed-off-by Tony Lindgren <[email protected]>
Quoted 4 lines

---

Anybody got better ideas for dealing with the missing elf.h defines?

Maybe:

#ifndef R_ARM_CALL
#warning "you're elf.h include is outdated"
#define R_ARM_CALL 28
#endif

Best regards
Uwe

Quoted 11 lines
scripts/mod/modpost.c +2 -0
@@ -1505,6 +1505,8 @@ static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
 		              (elf->symtab_start + ELF_R_SYM(r->r_info));
 		break;
 	case R_ARM_PC24:
+	case 28:		/* R_ARM_CALL */
+	case 29:		/* R_ARM_JUMP24 */
 		/* From ARM ABI: ((S + A) | T) - P */
 		r->r_addend = (int)(long)(elf->hdr +
 		              sechdr->sh_offset +
Signature · 2 lines
Pengutronix e.K.                           | Uwe Kleine-K?nig            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
#2 lore raw
Quoted 23 lines · Uwe Kleine-K?nig
Quoted 11 lines · Tony Lindgren

It turns out that many compilers don't show section warnings on ARM currently because handling for ARM_CALL relocs are missing from modpost.c.

Based on commit c2e26114 ([ARM] 3205/1: Handle new EABI relocations when loading kernel modules) it seems that R_ARM_PC24, R_ARM_CALL and R_ARM_JUMP24 can be handled the same way.

As modpost.c includes elf.h, we need to also consider that at least Debian libc6-dev is missing defines for both R_ARM_CALL and R_ARM_JUMP24 in /usr/include/elf.h.

Huh, even unstable's /usr/include/elf.h doesn't have these symbols.

Quoted 9 lines

So for now let's just use the numbers in modpost.c.

Cc Rusty Russell <[email protected]>
Cc Ben Hutchings <[email protected]>
Cc Anders Kaseorg <[email protected]>
Cc Greg KH <[email protected]>
Cc Russell King <[email protected]>
Signed-off-by Tony Lindgren <[email protected]>
Quoted 8 lines
Quoted 4 lines

---

Anybody got better ideas for dealing with the missing elf.h defines?

Maybe:

#ifndef R_ARM_CALL
#warning "you're elf.h include is outdated"

"You are elf.h include is outdated" does not make sense.

Why are you calling Tony an elf.h include?

Acked-by
#3 lore raw
Quoted 10 lines · Russell King - ARM Linux
Quoted 5 lines · Uwe Kleine-K?nig

On Mon, Feb 13, 2012 at 01:24:01PM -0800, Tony Lindgren wrote:
Maybe:

#ifndef R_ARM_CALL
#warning "you're elf.h include is outdated"

"You are elf.h include is outdated" does not make sense.

Why are you calling Tony an elf.h include?

Because he knew it would attract the attention of pedants to the patch? :)

Just do the #ifndef, and skip the warning. There's not much the poor user receiving the warning can do about it.

Acked-by Rusty Russell <[email protected]>

Thanks,
Rusty.

author Acked-by Rusty Russell
#4 lore raw
Quoted 8 lines · Rusty Russell
Quoted 7 lines · Russell King - ARM Linux
Quoted 5 lines · Uwe Kleine-K?nig

On Mon, Feb 13, 2012 at 01:24:01PM -0800, Tony Lindgren wrote:
Maybe:

#ifndef R_ARM_CALL
#warning "you're elf.h include is outdated"

Quoted 6 lines
Quoted 3 lines

"You are elf.h include is outdated" does not make sense.

Why are you calling Tony an elf.h include?

Because he knew it would attract the attention of pedants to the patch? :)

I've been called worse than that :)

Quoted 2 lines

Just do the #ifndef, and skip the warning. There's not much the poor user receiving the warning can do about it.

OK

Quoted 1 line
Acked-by Rusty Russell <[email protected]>

Assuming your ack applies for this patch below, let me know if that's not the case.
Regards,

Tony

From: Tony Lindgren <[email protected]>
Date: Mon, 13 Feb 2012 12:30:09 -0800
Subject: [PATCH] modpost: Fix section warnings for ARM for many compilers

It turns out that many compilers don't show section warnings on ARM currently because handling for ARM_CALL relocs are missing from modpost.c.

Based on commit c2e26114 ([ARM] 3205/1: Handle new EABI relocations when loading kernel modules) it seems that R_ARM_PC24, R_ARM_CALL and R_ARM_JUMP24 can be handled the same way.

Note that at least Debian libc6-dev is missing defines for both R_ARM_CALL and R_ARM_JUMP24 in /usr/include/elf.h. So for now we need to define them in modpost.c if not defined.

Acked-by Rusty Russell <[email protected]>
Cc Ben Hutchings <[email protected]>
Cc Anders Kaseorg <[email protected]>
Cc Greg KH <[email protected]>
Cc Russell King <[email protected]>
Signed-off-by Tony Lindgren <[email protected]>
scripts/mod/modpost.c +9 -0
@@ -1494,6 +1494,13 @@ static int addend_386_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
 	return 0;
 }
 
+#ifndef R_ARM_CALL
+#define R_ARM_CALL	28
+#endif
+#ifndef R_ARM_JUMP24
+#define R_ARM_JUMP24	29
+#endif
+
 static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
 {
 	unsigned int r_typ = ELF_R_TYPE(r->r_info);

@@ -1505,6 +1512,8 @@ static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)
 		              (elf->symtab_start + ELF_R_SYM(r->r_info));
 		break;
 	case R_ARM_PC24:
+	case R_ARM_CALL:
+	case R_ARM_JUMP24:
 		/* From ARM ABI: ((S + A) | T) - P */
 		r->r_addend = (int)(long)(elf->hdr +
 		              sechdr->sh_offset +
author
#5 lore raw
Quoted 21 lines · Tony Lindgren
Quoted 8 lines · Rusty Russell
Quoted 7 lines · Russell King - ARM Linux
Quoted 5 lines · Uwe Kleine-K?nig

On Mon, Feb 13, 2012 at 01:24:01PM -0800, Tony Lindgren wrote:
Maybe:

#ifndef R_ARM_CALL
#warning "you're elf.h include is outdated"

Quoted 6 lines
Quoted 3 lines

"You are elf.h include is outdated" does not make sense.

Why are you calling Tony an elf.h include?

Because he knew it would attract the attention of pedants to the patch? :)

I've been called worse than that :)

Quoted 2 lines

Just do the #ifndef, and skip the warning. There's not much the poor user receiving the warning can do about it.

Quoted 6 lines

OK

Quoted 1 line
Acked-by Rusty Russell <[email protected]>

Assuming your ack applies for this patch below, let me know if that's not the case.

This is now in Russell's patch tracking system as patch 7324/1.

Tony