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@@ -0,0 +1,46 @@
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+From: Ramin Moussavi <lordrasmus@gmail.com>
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+Subject: [PATCH] gcc: csky: define DWARF_ALT_FRAME_RETURN_COLUMN for signal-frame unwinding
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+
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+The csky signal-frame unwinder (gcc/config/csky/linux-unwind.h) restores
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+the interrupted PC into DWARF column 32. That column is not a hard
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+register, so init_dwarf_reg_size_table() leaves its size as 0 in
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+dwarf_reg_size_table. When the unwinder later walks through a signal
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+frame, _Unwind_GetGR() reads the size of column 32, finds 0 and aborts.
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+
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+In practice this makes any forced unwind through a signal frame abort
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+with SIGABRT. The most visible case is pthread cancellation: a thread
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+cancelled while blocked in a syscall is resumed via a signal frame, and
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+the cleanup unwind dies in _Unwind_GetGR() instead of running the
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+cancellation handlers. All NPTL cancellation tests of the uClibc-ng test
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+suite fail this way on csky.
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+
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+Declare column 32 as the alternate return column so
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+init_dwarf_reg_size_table() sizes it. This is the same mechanism arm,
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+aarch64, riscv and others already use for their signal return address
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+column. With this patch the 8 cancellation tests pass on csky.
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+
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+The macro has never been defined for csky, so this affects every gcc
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+version; the patch applies cleanly to 13.x/14.x/15.x. Reproduced and
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+verified with gcc 15.2.0 (uclibcabiv2, soft-float) on qemu-system-cskyv2.
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+
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+Signed-off-by: Ramin Moussavi <lordrasmus@gmail.com>
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+---
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+ gcc/config/csky/csky.h | 7 +++++++
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+ 1 file changed, 7 insertions(+)
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+
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+--- a/gcc/config/csky/csky.h
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++++ b/gcc/config/csky/csky.h
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+@@ -1007,6 +1007,13 @@
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+ define DWARF_FRAME_RETURN_COLUMN to DWARF_FRAME_REGNUM. */
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+ #define DWARF_FRAME_RETURN_COLUMN DWARF_FRAME_REGNUM (CSKY_LR_REGNUM)
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+
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++/* Signal frames (config/csky/linux-unwind.h) put the interrupted PC in
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++ DWARF column 32, which is not a hard register and thus is left unsized
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++ in dwarf_reg_size_table. Declare it as the alternate return column so
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++ init_dwarf_reg_size_table sizes it; otherwise _Unwind_GetGR aborts when
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++ unwinding through a signal frame (e.g. pthread cancellation). */
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++#define DWARF_ALT_FRAME_RETURN_COLUMN 32
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++
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+ /* Use r0 and r1 to pass exception handling information. */
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+ #define EH_RETURN_DATA_REGNO(N) ((N) < 2 ? N : INVALID_REGNUM)
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+
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Waldemar Brodkorb