[linux] 01/01: [powerpc*] Fix module linking to work with binutils 2.26 (Closes: #808043)
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Mon Mar 7 19:23:58 UTC 2016
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commit 80ba0eaab850dfaded35dfe0adb2bd5814b74c00
Author: Ben Hutchings <ben at decadent.org.uk>
Date: Mon Mar 7 15:37:29 2016 +0000
[powerpc*] Fix module linking to work with binutils 2.26 (Closes: #808043)
Cherry-picked these two patches from upstream:
- Simplify module TOC handling
- Fix dedotify for binutils >= 2.26
---
debian/changelog | 3 +
.../powerpc-fix-dedotify-for-binutils-2.26.patch | 34 ++++++
.../powerpc-simplify-module-toc-handling.patch | 125 +++++++++++++++++++++
debian/patches/series | 2 +
4 files changed, 164 insertions(+)
diff --git a/debian/changelog b/debian/changelog
index 31250bc..29cc108 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -454,6 +454,9 @@ linux (4.4.4-1) UNRELEASED; urgency=medium
* Fix/ignore module ABI changes in 4.4.4 as appropriate
* Revert "drm/radeon: call hpd_irq_event on resume", reported to cause
regressions (crash/hang) on some systems
+ * [powerpc*] Fix module linking to work with binutils 2.26 (Closes: #808043):
+ - Simplify module TOC handling
+ - Fix dedotify for binutils >= 2.26
[ Ian Campbell ]
* [armhf] dts: Add DTB for Novena, patches from Vagrant Cascadian
diff --git a/debian/patches/bugfix/powerpc/powerpc-fix-dedotify-for-binutils-2.26.patch b/debian/patches/bugfix/powerpc/powerpc-fix-dedotify-for-binutils-2.26.patch
new file mode 100644
index 0000000..a438f56
--- /dev/null
+++ b/debian/patches/bugfix/powerpc/powerpc-fix-dedotify-for-binutils-2.26.patch
@@ -0,0 +1,34 @@
+From: Andreas Schwab <schwab at linux-m68k.org>
+Date: Fri, 5 Feb 2016 19:50:03 +0100
+Subject: powerpc: Fix dedotify for binutils >= 2.26
+Origin: https://git.kernel.org/linus/f15838e9cac8f78f0cc506529bb9d3b9fa589c1f
+
+Since binutils 2.26 BFD is doing suffix merging on STRTAB sections. But
+dedotify modifies the symbol names in place, which can also modify
+unrelated symbols with a name that matches a suffix of a dotted name. To
+remove the leading dot of a symbol name we can just increment the pointer
+into the STRTAB section instead.
+
+Backport to all stables to avoid breakage when people update their
+binutils - mpe.
+
+Cc: stable at vger.kernel.org
+Signed-off-by: Andreas Schwab <schwab at linux-m68k.org>
+Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
+---
+ arch/powerpc/kernel/module_64.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
+index ac64ffdb52c8..08b7a40de5f8 100644
+--- a/arch/powerpc/kernel/module_64.c
++++ b/arch/powerpc/kernel/module_64.c
+@@ -340,7 +340,7 @@ static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
+ if (name[0] == '.') {
+ if (strcmp(name+1, "TOC.") == 0)
+ syms[i].st_shndx = SHN_ABS;
+- memmove(name, name+1, strlen(name));
++ syms[i].st_name++;
+ }
+ }
+ }
diff --git a/debian/patches/bugfix/powerpc/powerpc-simplify-module-toc-handling.patch b/debian/patches/bugfix/powerpc/powerpc-simplify-module-toc-handling.patch
new file mode 100644
index 0000000..3caeb01
--- /dev/null
+++ b/debian/patches/bugfix/powerpc/powerpc-simplify-module-toc-handling.patch
@@ -0,0 +1,125 @@
+From: Alan Modra <amodra at gmail.com>
+Date: Fri, 15 Jan 2016 20:52:22 +1100
+Subject: powerpc: Simplify module TOC handling
+Origin: https://git.kernel.org/linus/c153693d7eb9eeb28478aa2deaaf0b4e7b5ff5e9
+
+PowerPC64 uses the symbol .TOC. much as other targets use
+_GLOBAL_OFFSET_TABLE_. It identifies the value of the GOT pointer (or in
+powerpc parlance, the TOC pointer). Global offset tables are generally
+local to an executable or shared library, or in the kernel, module. Thus
+it does not make sense for a module to resolve a relocation against
+.TOC. to the kernel's .TOC. value. A module has its own .TOC., and
+indeed the powerpc64 module relocation processing ignores the kernel
+value of .TOC. and instead calculates a module-local value.
+
+This patch removes code involved in exporting the kernel .TOC., tweaks
+modpost to ignore an undefined .TOC., and the module loader to twiddle
+the section symbol so that .TOC. isn't seen as undefined.
+
+Note that if the kernel was compiled with -msingle-pic-base then ELFv2
+would not have function global entry code setting up r2. In that case
+the module call stubs would need to be modified to set up r2 using the
+kernel .TOC. value, requiring some of this code to be reinstated.
+
+mpe: Furthermore a change in binutils master (not yet released) causes
+the current way we handle the TOC to no longer work when building with
+MODVERSIONS=y and RELOCATABLE=n. The symptom is that modules can not be
+loaded due to there being no version found for TOC.
+
+Cc: stable at vger.kernel.org # 3.16+
+Signed-off-by: Alan Modra <amodra at gmail.com>
+Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
+---
+ arch/powerpc/kernel/misc_64.S | 28 ----------------------------
+ arch/powerpc/kernel/module_64.c | 12 +++++++++---
+ scripts/mod/modpost.c | 3 ++-
+ 3 files changed, 11 insertions(+), 32 deletions(-)
+
+diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
+index db475d41b57a..f28754c497e5 100644
+--- a/arch/powerpc/kernel/misc_64.S
++++ b/arch/powerpc/kernel/misc_64.S
+@@ -701,31 +701,3 @@ _GLOBAL(kexec_sequence)
+ li r5,0
+ blr /* image->start(physid, image->start, 0); */
+ #endif /* CONFIG_KEXEC */
+-
+-#ifdef CONFIG_MODULES
+-#if defined(_CALL_ELF) && _CALL_ELF == 2
+-
+-#ifdef CONFIG_MODVERSIONS
+-.weak __crc_TOC.
+-.section "___kcrctab+TOC.","a"
+-.globl __kcrctab_TOC.
+-__kcrctab_TOC.:
+- .llong __crc_TOC.
+-#endif
+-
+-/*
+- * Export a fake .TOC. since both modpost and depmod will complain otherwise.
+- * Both modpost and depmod strip the leading . so we do the same here.
+- */
+-.section "__ksymtab_strings","a"
+-__kstrtab_TOC.:
+- .asciz "TOC."
+-
+-.section "___ksymtab+TOC.","a"
+-/* This symbol name is important: it's used by modpost to find exported syms */
+-.globl __ksymtab_TOC.
+-__ksymtab_TOC.:
+- .llong 0 /* .value */
+- .llong __kstrtab_TOC.
+-#endif /* ELFv2 */
+-#endif /* MODULES */
+diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
+index 59663af9315f..ac64ffdb52c8 100644
+--- a/arch/powerpc/kernel/module_64.c
++++ b/arch/powerpc/kernel/module_64.c
+@@ -326,7 +326,10 @@ static void dedotify_versions(struct modversion_info *vers,
+ }
+ }
+
+-/* Undefined symbols which refer to .funcname, hack to funcname (or .TOC.) */
++/*
++ * Undefined symbols which refer to .funcname, hack to funcname. Make .TOC.
++ * seem to be defined (value set later).
++ */
+ static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
+ {
+ unsigned int i;
+@@ -334,8 +337,11 @@ static void dedotify(Elf64_Sym *syms, unsigned int numsyms, char *strtab)
+ for (i = 1; i < numsyms; i++) {
+ if (syms[i].st_shndx == SHN_UNDEF) {
+ char *name = strtab + syms[i].st_name;
+- if (name[0] == '.')
++ if (name[0] == '.') {
++ if (strcmp(name+1, "TOC.") == 0)
++ syms[i].st_shndx = SHN_ABS;
+ memmove(name, name+1, strlen(name));
++ }
+ }
+ }
+ }
+@@ -351,7 +357,7 @@ static Elf64_Sym *find_dot_toc(Elf64_Shdr *sechdrs,
+ numsyms = sechdrs[symindex].sh_size / sizeof(Elf64_Sym);
+
+ for (i = 1; i < numsyms; i++) {
+- if (syms[i].st_shndx == SHN_UNDEF
++ if (syms[i].st_shndx == SHN_ABS
+ && strcmp(strtab + syms[i].st_name, "TOC.") == 0)
+ return &syms[i];
+ }
+diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
+index e080746e1a6b..48958d3cec9e 100644
+--- a/scripts/mod/modpost.c
++++ b/scripts/mod/modpost.c
+@@ -594,7 +594,8 @@ static int ignore_undef_symbol(struct elf_info *info, const char *symname)
+ if (strncmp(symname, "_restgpr0_", sizeof("_restgpr0_") - 1) == 0 ||
+ strncmp(symname, "_savegpr0_", sizeof("_savegpr0_") - 1) == 0 ||
+ strncmp(symname, "_restvr_", sizeof("_restvr_") - 1) == 0 ||
+- strncmp(symname, "_savevr_", sizeof("_savevr_") - 1) == 0)
++ strncmp(symname, "_savevr_", sizeof("_savevr_") - 1) == 0 ||
++ strcmp(symname, ".TOC.") == 0)
+ return 1;
+ /* Do not ignore this symbol */
+ return 0;
diff --git a/debian/patches/series b/debian/patches/series
index 9ec006a..26e324b 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -133,3 +133,5 @@ debian/thermal-fix-abi-change-in-4.4.4.patch
debian/ipv4-fix-abi-change-in-4.4.4.patch
debian/ipv6-fix-abi-change-in-4.4.4.patch
bugfix/all/revert-drm-radeon-call-hpd_irq_event-on-resume.patch
+bugfix/powerpc/powerpc-simplify-module-toc-handling.patch
+bugfix/powerpc/powerpc-fix-dedotify-for-binutils-2.26.patch
--
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