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powerpc/lib: Add helper to check if offset is within conditional branch range
Add a helper to check if a given offset is within the branch range for a powerpc conditional branch instruction, and update some sites to use the new helper. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Song Liu <songliubraving@fb.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/442b69a34ced32ca346a0d9a855f3f6cfdbbbd41.1633464148.git.naveen.n.rao@linux.vnet.ibm.com
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3 changed files with 8 additions and 7 deletions
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@ -23,6 +23,7 @@
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#define BRANCH_ABSOLUTE 0x2
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#define BRANCH_ABSOLUTE 0x2
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bool is_offset_in_branch_range(long offset);
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bool is_offset_in_branch_range(long offset);
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bool is_offset_in_cond_branch_range(long offset);
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int create_branch(struct ppc_inst *instr, const u32 *addr,
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int create_branch(struct ppc_inst *instr, const u32 *addr,
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unsigned long target, int flags);
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unsigned long target, int flags);
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int create_cond_branch(struct ppc_inst *instr, const u32 *addr,
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int create_cond_branch(struct ppc_inst *instr, const u32 *addr,
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@ -228,6 +228,11 @@ bool is_offset_in_branch_range(long offset)
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return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
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return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));
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}
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}
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bool is_offset_in_cond_branch_range(long offset)
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{
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return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3);
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}
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/*
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/*
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* Helper to check if a given instruction is a conditional branch
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* Helper to check if a given instruction is a conditional branch
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* Derived from the conditional checks in analyse_instr()
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* Derived from the conditional checks in analyse_instr()
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@ -280,7 +285,7 @@ int create_cond_branch(struct ppc_inst *instr, const u32 *addr,
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offset = offset - (unsigned long)addr;
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offset = offset - (unsigned long)addr;
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/* Check we can represent the target in the instruction format */
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/* Check we can represent the target in the instruction format */
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if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
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if (!is_offset_in_cond_branch_range(offset))
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return 1;
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return 1;
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/* Mask out the flags and target, so they don't step on each other. */
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/* Mask out the flags and target, so they don't step on each other. */
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@ -78,11 +78,6 @@
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#define PPC_FUNC_ADDR(d,i) do { PPC_LI32(d, i); } while(0)
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#define PPC_FUNC_ADDR(d,i) do { PPC_LI32(d, i); } while(0)
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#endif
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#endif
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static inline bool is_nearbranch(int offset)
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{
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return (offset < 32768) && (offset >= -32768);
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}
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/*
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/*
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* The fly in the ointment of code size changing from pass to pass is
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* The fly in the ointment of code size changing from pass to pass is
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* avoided by padding the short branch case with a NOP. If code size differs
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* avoided by padding the short branch case with a NOP. If code size differs
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@ -91,7 +86,7 @@ static inline bool is_nearbranch(int offset)
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* state.
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* state.
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*/
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*/
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#define PPC_BCC(cond, dest) do { \
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#define PPC_BCC(cond, dest) do { \
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if (is_nearbranch((dest) - (ctx->idx * 4))) { \
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if (is_offset_in_cond_branch_range((long)(dest) - (ctx->idx * 4))) { \
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PPC_BCC_SHORT(cond, dest); \
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PPC_BCC_SHORT(cond, dest); \
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EMIT(PPC_RAW_NOP()); \
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EMIT(PPC_RAW_NOP()); \
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} else { \
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} else { \
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