4.4-stable review patch. If anyone has any objections, please let me know.
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From: Maciej W. Rozycki macro@mips.com
commit 547da673173de51f73887377eb275304775064ad upstream.
Fix a commit 7aeb753b5353 ("MIPS: Implement task_user_regset_view.") regression, then activated by commit 6a9c001b7ec3 ("MIPS: Switch ELF core dumper to use regsets.)", that caused n32 processes to dump o32 core files by failing to set the EF_MIPS_ABI2 flag in the ELF core file header's `e_flags' member:
$ file tls-core tls-core: ELF 32-bit MSB executable, MIPS, N32 MIPS64 rel2 version 1 (SYSV), [...] $ ./tls-core Aborted (core dumped) $ file core core: ELF 32-bit MSB core file MIPS, MIPS-I version 1 (SYSV), SVR4-style $
Previously the flag was set as the result of a:
statement placed in arch/mips/kernel/binfmt_elfn32.c, however in the regset case, i.e. when CORE_DUMP_USE_REGSET is set, ELF_CORE_EFLAGS is no longer used by `fill_note_info' in fs/binfmt_elf.c, and instead the `->e_flags' member of the regset view chosen is. We have the views defined in arch/mips/kernel/ptrace.c, however only an o32 and an n64 one, and the latter is used for n32 as well. Consequently an o32 core file is incorrectly dumped from n32 processes (the ELF32 vs ELF64 class is chosen elsewhere, and the 32-bit one is correctly selected for n32).
Correct the issue then by defining an n32 regset view and using it as appropriate. Issue discovered in GDB testing.
Fixes: 7aeb753b5353 ("MIPS: Implement task_user_regset_view.") Signed-off-by: Maciej W. Rozycki macro@mips.com Cc: Ralf Baechle ralf@linux-mips.org Cc: Djordje Todorovic djordje.todorovic@rt-rk.com Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/17617/ Signed-off-by: James Hogan jhogan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/mips/kernel/ptrace.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
--- a/arch/mips/kernel/ptrace.c +++ b/arch/mips/kernel/ptrace.c @@ -650,6 +650,19 @@ static const struct user_regset_view use .n = ARRAY_SIZE(mips64_regsets), };
+#ifdef CONFIG_MIPS32_N32 + +static const struct user_regset_view user_mipsn32_view = { + .name = "mipsn32", + .e_flags = EF_MIPS_ABI2, + .e_machine = ELF_ARCH, + .ei_osabi = ELF_OSABI, + .regsets = mips64_regsets, + .n = ARRAY_SIZE(mips64_regsets), +}; + +#endif /* CONFIG_MIPS32_N32 */ + #endif /* CONFIG_64BIT */
const struct user_regset_view *task_user_regset_view(struct task_struct *task) @@ -661,6 +674,10 @@ const struct user_regset_view *task_user if (test_tsk_thread_flag(task, TIF_32BIT_REGS)) return &user_mips_view; #endif +#ifdef CONFIG_MIPS32_N32 + if (test_tsk_thread_flag(task, TIF_32BIT_ADDR)) + return &user_mipsn32_view; +#endif return &user_mips64_view; #endif }