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[PATCH 0/5] Support new MIPSr6 relocations

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  [PATCH 0/5] Support new MIPSr6 relocations Paul Burton <paul.burton@imgtec.com> - 2016-02-03 04:50 +0100
    [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc Paul Burton <paul.burton@imgtec.com> - 2016-02-03 04:50 +0100
      Re: [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2016-02-03 11:30 +0100
        Re: [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc Paul Burton <paul.burton@imgtec.com> - 2016-02-03 11:40 +0100
          Re: [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2016-02-03 11:40 +0100
            Re: [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc Paul Burton <paul.burton@imgtec.com> - 2016-02-03 11:50 +0100
      Re: [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc James Hogan <james.hogan@imgtec.com> - 2016-02-03 13:50 +0100
    [PATCH 3/5] MIPS: Add support for 64-bit R6 ELF relocations Paul Burton <paul.burton@imgtec.com> - 2016-02-03 04:50 +0100

#1324886 — [PATCH 0/5] Support new MIPSr6 relocations

MIPSr6 introduced a few new relocations that may be present in loadable
kernel modules. This series introduces support for them in both their
rel & rela forms for MIPS32 & MIPS64 kernels respectively, and ensures
that any future missing relocs cause module loading to fail gracefully.

Paul Burton (3):
  MIPS: Bail on unsupported module relocs
  MIPS: Support R_MIPS_PC16 rel-style reloc
  MIPS: Implement MIPSr6 R_MIPS_PC2x rel-style relocs

Steven J. Hill (2):
  MIPS: module-rela: Make consistent use of pr_*()
  MIPS: Add support for 64-bit R6 ELF relocations

 arch/mips/include/asm/elf.h    |  5 +++
 arch/mips/kernel/module-rela.c | 96 ++++++++++++++++++++++++++++++++++++++----
 arch/mips/kernel/module.c      | 85 +++++++++++++++++++++++++++++++++++--
 3 files changed, 173 insertions(+), 13 deletions(-)

-- 
2.7.0

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#1324887 — [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc

MIPS32 code uses rel-style relocs, and MIPS32r6 modules may include the
R_MIPS_PC16 relocation. We thus need to support R_MIPS_PC16 rel-style
relocations in order to load MIPS32r6 kernel modules. This patch adds
such support, which is similar to the rela-style R_MIPS_PC16 support but
making use of the implicit addend from the instruction encoding.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
---

 arch/mips/kernel/module.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
index 2adf572..f2de9b8 100644
--- a/arch/mips/kernel/module.c
+++ b/arch/mips/kernel/module.c
@@ -183,13 +183,25 @@ out_danger:
 	return -ENOEXEC;
 }
 
+static int apply_r_mips_pc16_rel(struct module *me, u32 *location, Elf_Addr v)
+{
+	u16 val;
+
+	val = *location;
+	val += (v - (Elf_Addr)location) >> 2;
+	*location = (*location & 0xffff0000) | val;
+
+	return 0;
+}
+
 static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
 				Elf_Addr v) = {
 	[R_MIPS_NONE]		= apply_r_mips_none,
 	[R_MIPS_32]		= apply_r_mips_32_rel,
 	[R_MIPS_26]		= apply_r_mips_26_rel,
 	[R_MIPS_HI16]		= apply_r_mips_hi16_rel,
-	[R_MIPS_LO16]		= apply_r_mips_lo16_rel
+	[R_MIPS_LO16]		= apply_r_mips_lo16_rel,
+	[R_MIPS_PC16]		= apply_r_mips_pc16_rel,
 };
 
 int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
-- 
2.7.0

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#1325159 — Re: [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc

Hello.

On 2/3/2016 6:44 AM, Paul Burton wrote:

> MIPS32 code uses rel-style relocs, and MIPS32r6 modules may include the
> R_MIPS_PC16 relocation. We thus need to support R_MIPS_PC16 rel-style
> relocations in order to load MIPS32r6 kernel modules. This patch adds
> such support, which is similar to the rela-style R_MIPS_PC16 support but

     R_MIPS_LO16, you mean?

> making use of the implicit addend from the instruction encoding.
>
> Signed-off-by: Paul Burton <paul.burton@imgtec.com>
> ---
>
>   arch/mips/kernel/module.c | 14 +++++++++++++-
>   1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
> index 2adf572..f2de9b8 100644
> --- a/arch/mips/kernel/module.c
> +++ b/arch/mips/kernel/module.c
> @@ -183,13 +183,25 @@ out_danger:
>   	return -ENOEXEC;
>   }
>
> +static int apply_r_mips_pc16_rel(struct module *me, u32 *location, Elf_Addr v)
> +{
> +	u16 val;
> +
> +	val = *location;
> +	val += (v - (Elf_Addr)location) >> 2;
> +	*location = (*location & 0xffff0000) | val;
> +
> +	return 0;
> +}
> +
>   static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
>   				Elf_Addr v) = {
>   	[R_MIPS_NONE]		= apply_r_mips_none,
>   	[R_MIPS_32]		= apply_r_mips_32_rel,
>   	[R_MIPS_26]		= apply_r_mips_26_rel,
>   	[R_MIPS_HI16]		= apply_r_mips_hi16_rel,
> -	[R_MIPS_LO16]		= apply_r_mips_lo16_rel
> +	[R_MIPS_LO16]		= apply_r_mips_lo16_rel,
> +	[R_MIPS_PC16]		= apply_r_mips_pc16_rel,
>   };
>
>   int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,

MBR, Sergei

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#1325174 — Re: [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc

On Wed, Feb 03, 2016 at 01:25:57PM +0300, Sergei Shtylyov wrote:
> Hello.
> 
> On 2/3/2016 6:44 AM, Paul Burton wrote:
> >MIPS32 code uses rel-style relocs, and MIPS32r6 modules may include the
> >R_MIPS_PC16 relocation. We thus need to support R_MIPS_PC16 rel-style
> >relocations in order to load MIPS32r6 kernel modules. This patch adds
> >such support, which is similar to the rela-style R_MIPS_PC16 support but
> 
>     R_MIPS_LO16, you mean?

Hi Sergei,

No, I mean it's similar to the R_MIPS_PC16 code in module-rela.c. That
is, its rela-style equivalent (rather than rel-style as here).

Thanks,
    Paul

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#1325178 — Re: [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc

On 2/3/2016 1:32 PM, Paul Burton wrote:

>>> MIPS32 code uses rel-style relocs, and MIPS32r6 modules may include the
>>> R_MIPS_PC16 relocation. We thus need to support R_MIPS_PC16 rel-style
>>> relocations in order to load MIPS32r6 kernel modules. This patch adds
>>> such support, which is similar to the rela-style R_MIPS_PC16 support but
>>
>>      R_MIPS_LO16, you mean?
>
> Hi Sergei,
>
> No, I mean it's similar to the R_MIPS_PC16 code in module-rela.c. That
> is, its rela-style equivalent (rather than rel-style as here).

    But you're *adding* R_MIPS_PC16, no?

> Thanks,
>      Paul

MBR, Sergei

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#1325189 — Re: [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc

On Wed, Feb 03, 2016 at 01:36:00PM +0300, Sergei Shtylyov wrote:
> On 2/3/2016 1:32 PM, Paul Burton wrote:
> 
> >>>MIPS32 code uses rel-style relocs, and MIPS32r6 modules may include the
> >>>R_MIPS_PC16 relocation. We thus need to support R_MIPS_PC16 rel-style
> >>>relocations in order to load MIPS32r6 kernel modules. This patch adds
> >>>such support, which is similar to the rela-style R_MIPS_PC16 support but
> >>
> >>     R_MIPS_LO16, you mean?
> >
> >Hi Sergei,
> >
> >No, I mean it's similar to the R_MIPS_PC16 code in module-rela.c. That
> >is, its rela-style equivalent (rather than rel-style as here).
> 
>    But you're *adding* R_MIPS_PC16, no?

Yup, this patch is adding R_MIPS_PC16 to module.c & it's similar to
R_MIPS_PC16 in module-rela.c.

(Incidentally I think we could tidy up the duplication between the two
files, but that can come later...)

Thanks,
    Paul

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#1325362 — Re: [PATCH 4/5] MIPS: Support R_MIPS_PC16 rel-style reloc

[Multipart message — attachments visible in raw view] — view raw

On Wed, Feb 03, 2016 at 03:44:44AM +0000, Paul Burton wrote:
> MIPS32 code uses rel-style relocs, and MIPS32r6 modules may include the
> R_MIPS_PC16 relocation. We thus need to support R_MIPS_PC16 rel-style
> relocations in order to load MIPS32r6 kernel modules. This patch adds
> such support, which is similar to the rela-style R_MIPS_PC16 support but
> making use of the implicit addend from the instruction encoding.
> 
> Signed-off-by: Paul Burton <paul.burton@imgtec.com>
> ---
> 
>  arch/mips/kernel/module.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
> index 2adf572..f2de9b8 100644
> --- a/arch/mips/kernel/module.c
> +++ b/arch/mips/kernel/module.c
> @@ -183,13 +183,25 @@ out_danger:
>  	return -ENOEXEC;
>  }
>  
> +static int apply_r_mips_pc16_rel(struct module *me, u32 *location, Elf_Addr v)
> +{
> +	u16 val;
> +
> +	val = *location;
> +	val += (v - (Elf_Addr)location) >> 2;
> +	*location = (*location & 0xffff0000) | val;

Looks correct, but presumably this could benefit from some sanity
checking like the other patches.

Cheers
James

> +
> +	return 0;
> +}
> +
>  static int (*reloc_handlers_rel[]) (struct module *me, u32 *location,
>  				Elf_Addr v) = {
>  	[R_MIPS_NONE]		= apply_r_mips_none,
>  	[R_MIPS_32]		= apply_r_mips_32_rel,
>  	[R_MIPS_26]		= apply_r_mips_26_rel,
>  	[R_MIPS_HI16]		= apply_r_mips_hi16_rel,
> -	[R_MIPS_LO16]		= apply_r_mips_lo16_rel
> +	[R_MIPS_LO16]		= apply_r_mips_lo16_rel,
> +	[R_MIPS_PC16]		= apply_r_mips_pc16_rel,
>  };
>  
>  int apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
> -- 
> 2.7.0
> 
> 

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#1324889 — [PATCH 3/5] MIPS: Add support for 64-bit R6 ELF relocations

From: "Steven J. Hill" <Steven.Hill@imgtec.com>

This patch fixes MIPS64r6 kernel modules by adding new ELF
relocations. Toolchains that compile 64-bit R6 binaries emit
two new ELF relocations R_MIPS_PC21_S2 and R_MIPS_PC26_S2.
The pre-existing R_MIPS_PC16 ELF relocation is also emitted.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
---

 arch/mips/include/asm/elf.h    |  5 +++
 arch/mips/kernel/module-rela.c | 69 +++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h
index cefb7a5..7cec234 100644
--- a/arch/mips/include/asm/elf.h
+++ b/arch/mips/include/asm/elf.h
@@ -111,6 +111,11 @@
 #define R_MIPS_CALLHI16		30
 #define R_MIPS_CALLLO16		31
 /*
+ * Introduced for MIPSr6.
+ */
+#define R_MIPS_PC21_S2		60
+#define R_MIPS_PC26_S2		61
+/*
  * This range is reserved for vendor specific relocations.
  */
 #define R_MIPS_LOVENDOR		100
diff --git a/arch/mips/kernel/module-rela.c b/arch/mips/kernel/module-rela.c
index f1ff64b..2dbe1b0 100644
--- a/arch/mips/kernel/module-rela.c
+++ b/arch/mips/kernel/module-rela.c
@@ -16,6 +16,7 @@
  *  Copyright (C) 2001 Rusty Russell.
  *  Copyright (C) 2003, 2004 Ralf Baechle (ralf@linux-mips.org)
  *  Copyright (C) 2005 Thiemo Seufer
+ *  Copyright (C) 2015 Imagination Technologies Ltd.
  */
 
 #include <linux/elf.h>
@@ -65,6 +66,27 @@ static int apply_r_mips_lo16_rela(struct module *me, u32 *location, Elf_Addr v)
 	return 0;
 }
 
+static int apply_r_mips_pc16_rela(struct module *me, u32 *location, Elf_Addr v)
+{
+	long offset;
+
+	if (v % 4) {
+		pr_err("module %s: dangerous R_MIPS_PC16 RELA relocation\n",
+		       me->name);
+		return -ENOEXEC;
+	}
+
+	offset = ((long)v - (long)location) >> 2;
+	if (offset != (int16_t)offset) {
+		pr_err("module %s: relocation overflow\n", me->name);
+		return -ENOEXEC;
+	}
+
+	*location = (*location & ~0xffff) | (offset & 0xffff);
+
+	return 0;
+}
+
 static int apply_r_mips_64_rela(struct module *me, u32 *location, Elf_Addr v)
 {
 	*(Elf_Addr *)location = v;
@@ -90,6 +112,48 @@ static int apply_r_mips_highest_rela(struct module *me, u32 *location,
 	return 0;
 }
 
+static int apply_r_mips_pc21_rela(struct module *me, u32 *location, Elf_Addr v)
+{
+	long offset;
+
+	if (v % 4) {
+		pr_err("module %s: dangerous R_MIPS_PC21 RELA relocation\n",
+		       me->name);
+		return -ENOEXEC;
+	}
+
+	offset = ((long)v - (long)location) >> 2;
+	if ((offset >> 20) > 0 || (offset >> 20) < -1) {
+		pr_err("module %s: relocation overflow\n", me->name);
+		return -ENOEXEC;
+	}
+
+	*location = (*location & ~0x001fffff) | (offset & 0x001fffff);
+
+	return 0;
+}
+
+static int apply_r_mips_pc26_rela(struct module *me, u32 *location, Elf_Addr v)
+{
+	long offset;
+
+	if (v % 4) {
+		pr_err("module %s: dangerous R_MIPS_PC26 RELA relocation\n",
+		       me->name);
+		return -ENOEXEC;
+	}
+
+	offset = ((long)v - (long)location) >> 2;
+	if ((offset >> 25) > 0 || (offset >> 25) < -1) {
+		pr_err("module %s: relocation overflow\n", me->name);
+		return -ENOEXEC;
+	}
+
+	*location = (*location & ~0x03ffffff) | (offset & 0x03ffffff);
+
+	return 0;
+}
+
 static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 				Elf_Addr v) = {
 	[R_MIPS_NONE]		= apply_r_mips_none,
@@ -97,9 +161,12 @@ static int (*reloc_handlers_rela[]) (struct module *me, u32 *location,
 	[R_MIPS_26]		= apply_r_mips_26_rela,
 	[R_MIPS_HI16]		= apply_r_mips_hi16_rela,
 	[R_MIPS_LO16]		= apply_r_mips_lo16_rela,
+	[R_MIPS_PC16]		= apply_r_mips_pc16_rela,
 	[R_MIPS_64]		= apply_r_mips_64_rela,
 	[R_MIPS_HIGHER]		= apply_r_mips_higher_rela,
-	[R_MIPS_HIGHEST]	= apply_r_mips_highest_rela
+	[R_MIPS_HIGHEST]	= apply_r_mips_highest_rela,
+	[R_MIPS_PC21_S2]	= apply_r_mips_pc21_rela,
+	[R_MIPS_PC26_S2]	= apply_r_mips_pc26_rela,
 };
 
 int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
-- 
2.7.0

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