Commit 4549c3ea authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Michael Ellerman
Browse files

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: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/442b69a34ced32ca346a0d9a855f3f6cfdbbbd41.1633464148.git.naveen.n.rao@linux.vnet.ibm.com
parent 23c216b3

arch/powerpc/include/asm/code-patching.h

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#define BRANCH_ABSOLUTE	0x2



bool is_offset_in_branch_range(long offset);

bool is_offset_in_cond_branch_range(long offset);

int create_branch(struct ppc_inst *instr, const u32 *addr,

		  unsigned long target, int flags);

int create_cond_branch(struct ppc_inst *instr, const u32 *addr,

arch/powerpc/lib/code-patching.c

+6 −1
Original line number Diff line number Diff line
@@ -228,6 +228,11 @@ bool is_offset_in_branch_range(long offset) 
	return (offset >= -0x2000000 && offset <= 0x1fffffc && !(offset & 0x3));

}



bool is_offset_in_cond_branch_range(long offset)

{

	return offset >= -0x8000 && offset <= 0x7fff && !(offset & 0x3);

}



/*

 * Helper to check if a given instruction is a conditional branch

 * Derived from the conditional checks in analyse_instr()
@@ -280,7 +285,7 @@ int create_cond_branch(struct ppc_inst *instr, const u32 *addr, 
		offset = offset - (unsigned long)addr;



	/* Check we can represent the target in the instruction format */

	if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)

	if (!is_offset_in_cond_branch_range(offset))

		return 1;



	/* Mask out the flags and target, so they don't step on each other. */

arch/powerpc/net/bpf_jit.h

+1 −6
Original line number Diff line number Diff line
@@ -78,11 +78,6 @@ 
#define PPC_FUNC_ADDR(d,i) do { PPC_LI32(d, i); } while(0)

#endif



static inline bool is_nearbranch(int offset)

{

	return (offset < 32768) && (offset >= -32768);

}



/*

 * The fly in the ointment of code size changing from pass to pass is

 * avoided by padding the short branch case with a NOP.	 If code size differs
@@ -91,7 +86,7 @@ static inline bool is_nearbranch(int offset) 
 * state.

 */

#define PPC_BCC(cond, dest)	do {					      \

		if (is_nearbranch((dest) - (ctx->idx * 4))) {		      \

		if (is_offset_in_cond_branch_range((long)(dest) - (ctx->idx * 4))) {	\

			PPC_BCC_SHORT(cond, dest);			      \

			EMIT(PPC_RAW_NOP());				      \

		} else {						      \