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commit: e08bdc6ca7fec4ff403493157ca3ae663bace3a6 |
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Author: Alice Ferrazzi <alicef <AT> gentoo <DOT> org> |
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AuthorDate: Wed Feb 28 20:06:15 2018 +0000 |
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Commit: Alice Ferrazzi <alicef <AT> gentoo <DOT> org> |
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CommitDate: Wed Feb 28 20:06:15 2018 +0000 |
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URL: https://gitweb.gentoo.org/proj/linux-patches.git/commit/?id=e08bdc6c |
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|
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ia64 fix ptrace patch |
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|
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1700_ia64_fix_ptrace.patch | 87 ++++++++++++++++++++++++++++++++++++++++++++++ |
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1 file changed, 87 insertions(+) |
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|
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diff --git a/1700_ia64_fix_ptrace.patch b/1700_ia64_fix_ptrace.patch |
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new file mode 100644 |
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index 0000000..6173b05 |
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--- /dev/null |
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+++ b/1700_ia64_fix_ptrace.patch |
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@@ -0,0 +1,87 @@ |
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+From patchwork Fri Feb 2 22:12:24 2018 |
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+Content-Type: text/plain; charset="utf-8" |
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+MIME-Version: 1.0 |
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+Content-Transfer-Encoding: 8bit |
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+Subject: ia64: fix ptrace(PTRACE_GETREGS) (unbreaks strace, gdb) |
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+From: Sergei Trofimovich <slyfox@g.o> |
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+X-Patchwork-Id: 10198159 |
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+Message-Id: <20180202221224.16597-1-slyfox@g.o> |
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+To: Tony Luck <tony.luck@×××××.com>, Fenghua Yu <fenghua.yu@×××××.com>, |
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+ linux-ia64@×××××××××××.org, linux-kernel@×××××××××××.org |
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+Cc: Sergei Trofimovich <slyfox@g.o> |
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+Date: Fri, 2 Feb 2018 22:12:24 +0000 |
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+ |
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+The strace breakage looks like that: |
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+./strace: get_regs: get_regs_error: Input/output error |
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+ |
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+It happens because ia64 needs to load unwind tables |
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+to read certain registers. Unwind tables fail to load |
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+due to GCC quirk on the following code: |
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+ |
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+ extern char __end_unwind[]; |
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+ const struct unw_table_entry *end = (struct unw_table_entry *)table_end; |
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+ table->end = segment_base + end[-1].end_offset; |
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+ |
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+GCC does not generate correct code for this single memory |
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+reference after constant propagation (see https://gcc.gnu.org/PR84184). |
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+Two triggers are required for bad code generation: |
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+- '__end_unwind' has alignment lower (char), than |
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+ 'struct unw_table_entry' (8). |
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+- symbol offset is negative. |
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+ |
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+This commit workarounds it by fixing alignment of '__end_unwind'. |
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+While at it use hidden symbols to generate shorter gp-relative |
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+relocations. |
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+ |
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+CC: Tony Luck <tony.luck@×××××.com> |
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+CC: Fenghua Yu <fenghua.yu@×××××.com> |
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+CC: linux-ia64@×××××××××××.org |
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+CC: linux-kernel@×××××××××××.org |
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+Bug: https://github.com/strace/strace/issues/33 |
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+Bug: https://gcc.gnu.org/PR84184 |
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+Reported-by: Émeric Maschino <emeric.maschino@×××××.com> |
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+Signed-off-by: Sergei Trofimovich <slyfox@g.o> |
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+Tested-by: stanton_arch@××××.com |
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+--- |
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+ arch/ia64/include/asm/sections.h | 1 - |
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+ arch/ia64/kernel/unwind.c | 15 ++++++++++++++- |
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+ 2 files changed, 14 insertions(+), 2 deletions(-) |
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+ |
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+diff --git a/arch/ia64/include/asm/sections.h b/arch/ia64/include/asm/sections.h |
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+index f3481408594e..0fc4f1757a44 100644 |
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+--- a/arch/ia64/include/asm/sections.h |
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++++ b/arch/ia64/include/asm/sections.h |
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+@@ -24,7 +24,6 @@ extern char __start_gate_mckinley_e9_patchlist[], __end_gate_mckinley_e9_patchli |
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+ extern char __start_gate_vtop_patchlist[], __end_gate_vtop_patchlist[]; |
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+ extern char __start_gate_fsyscall_patchlist[], __end_gate_fsyscall_patchlist[]; |
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+ extern char __start_gate_brl_fsys_bubble_down_patchlist[], __end_gate_brl_fsys_bubble_down_patchlist[]; |
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+-extern char __start_unwind[], __end_unwind[]; |
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+ extern char __start_ivt_text[], __end_ivt_text[]; |
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+ |
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+ #undef dereference_function_descriptor |
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+diff --git a/arch/ia64/kernel/unwind.c b/arch/ia64/kernel/unwind.c |
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+index e04efa088902..025ba6700790 100644 |
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+--- a/arch/ia64/kernel/unwind.c |
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++++ b/arch/ia64/kernel/unwind.c |
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+@@ -2243,7 +2243,20 @@ __initcall(create_gate_table); |
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+ void __init |
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+ unw_init (void) |
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+ { |
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+- extern char __gp[]; |
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++ #define __ia64_hidden __attribute__((visibility("hidden"))) |
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++ /* |
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++ * We use hidden symbols to generate more efficient code using |
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++ * gp-relative addressing. |
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++ */ |
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++ extern char __gp[] __ia64_hidden; |
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++ /* |
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++ * Unwind tables need to have proper alignment as init_unwind_table() |
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++ * uses negative offsets against '__end_unwind'. |
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++ * See https://gcc.gnu.org/PR84184 |
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++ */ |
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++ extern const struct unw_table_entry __start_unwind[] __ia64_hidden; |
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++ extern const struct unw_table_entry __end_unwind[] __ia64_hidden; |
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++ #undef __ia64_hidden |
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+ extern void unw_hash_index_t_is_too_narrow (void); |
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+ long i, off; |
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+ |
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