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author | Alice Ferrazzi <alicef@gentoo.org> | 2018-02-28 20:06:15 +0000 |
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committer | Alice Ferrazzi <alicef@gentoo.org> | 2018-02-28 20:06:15 +0000 |
commit | e08bdc6ca7fec4ff403493157ca3ae663bace3a6 (patch) | |
tree | 9c3d4c00d84d7a6165d4105c9c71a9f745a0f66e | |
parent | ia64 fix ptrace (restore from wrong commit) (diff) | |
download | linux-patches-e08bdc6ca7fec4ff403493157ca3ae663bace3a6.tar.gz linux-patches-e08bdc6ca7fec4ff403493157ca3ae663bace3a6.tar.bz2 linux-patches-e08bdc6ca7fec4ff403493157ca3ae663bace3a6.zip |
ia64 fix ptrace patch4.15-8
-rw-r--r-- | 1700_ia64_fix_ptrace.patch | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/1700_ia64_fix_ptrace.patch b/1700_ia64_fix_ptrace.patch new file mode 100644 index 00000000..6173b053 --- /dev/null +++ b/1700_ia64_fix_ptrace.patch @@ -0,0 +1,87 @@ +From patchwork Fri Feb 2 22:12:24 2018 +Content-Type: text/plain; charset="utf-8" +MIME-Version: 1.0 +Content-Transfer-Encoding: 8bit +Subject: ia64: fix ptrace(PTRACE_GETREGS) (unbreaks strace, gdb) +From: Sergei Trofimovich <slyfox@gentoo.org> +X-Patchwork-Id: 10198159 +Message-Id: <20180202221224.16597-1-slyfox@gentoo.org> +To: Tony Luck <tony.luck@intel.com>, Fenghua Yu <fenghua.yu@intel.com>, + linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org +Cc: Sergei Trofimovich <slyfox@gentoo.org> +Date: Fri, 2 Feb 2018 22:12:24 +0000 + +The strace breakage looks like that: +./strace: get_regs: get_regs_error: Input/output error + +It happens because ia64 needs to load unwind tables +to read certain registers. Unwind tables fail to load +due to GCC quirk on the following code: + + extern char __end_unwind[]; + const struct unw_table_entry *end = (struct unw_table_entry *)table_end; + table->end = segment_base + end[-1].end_offset; + +GCC does not generate correct code for this single memory +reference after constant propagation (see https://gcc.gnu.org/PR84184). +Two triggers are required for bad code generation: +- '__end_unwind' has alignment lower (char), than + 'struct unw_table_entry' (8). +- symbol offset is negative. + +This commit workarounds it by fixing alignment of '__end_unwind'. +While at it use hidden symbols to generate shorter gp-relative +relocations. + +CC: Tony Luck <tony.luck@intel.com> +CC: Fenghua Yu <fenghua.yu@intel.com> +CC: linux-ia64@vger.kernel.org +CC: linux-kernel@vger.kernel.org +Bug: https://github.com/strace/strace/issues/33 +Bug: https://gcc.gnu.org/PR84184 +Reported-by: Émeric Maschino <emeric.maschino@gmail.com> +Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org> +Tested-by: stanton_arch@mail.com +--- + arch/ia64/include/asm/sections.h | 1 - + arch/ia64/kernel/unwind.c | 15 ++++++++++++++- + 2 files changed, 14 insertions(+), 2 deletions(-) + +diff --git a/arch/ia64/include/asm/sections.h b/arch/ia64/include/asm/sections.h +index f3481408594e..0fc4f1757a44 100644 +--- a/arch/ia64/include/asm/sections.h ++++ b/arch/ia64/include/asm/sections.h +@@ -24,7 +24,6 @@ extern char __start_gate_mckinley_e9_patchlist[], __end_gate_mckinley_e9_patchli + extern char __start_gate_vtop_patchlist[], __end_gate_vtop_patchlist[]; + extern char __start_gate_fsyscall_patchlist[], __end_gate_fsyscall_patchlist[]; + extern char __start_gate_brl_fsys_bubble_down_patchlist[], __end_gate_brl_fsys_bubble_down_patchlist[]; +-extern char __start_unwind[], __end_unwind[]; + extern char __start_ivt_text[], __end_ivt_text[]; + + #undef dereference_function_descriptor +diff --git a/arch/ia64/kernel/unwind.c b/arch/ia64/kernel/unwind.c +index e04efa088902..025ba6700790 100644 +--- a/arch/ia64/kernel/unwind.c ++++ b/arch/ia64/kernel/unwind.c +@@ -2243,7 +2243,20 @@ __initcall(create_gate_table); + void __init + unw_init (void) + { +- extern char __gp[]; ++ #define __ia64_hidden __attribute__((visibility("hidden"))) ++ /* ++ * We use hidden symbols to generate more efficient code using ++ * gp-relative addressing. ++ */ ++ extern char __gp[] __ia64_hidden; ++ /* ++ * Unwind tables need to have proper alignment as init_unwind_table() ++ * uses negative offsets against '__end_unwind'. ++ * See https://gcc.gnu.org/PR84184 ++ */ ++ extern const struct unw_table_entry __start_unwind[] __ia64_hidden; ++ extern const struct unw_table_entry __end_unwind[] __ia64_hidden; ++ #undef __ia64_hidden + extern void unw_hash_index_t_is_too_narrow (void); + long i, off; + |