Re: [PATCH 1/9] powerpc/lib: Add helper to check if offset is within conditional branch range
From: Song Liu <song@kernel.org>
Date: 2021-10-01 21:37:47
Also in:
bpf
On Fri, Oct 1, 2021 at 2:16 PM Naveen N. Rao [off-list ref] wrote:
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 <redacted>
Acked-by: Song Liu <redacted> With one nitpick:
quoted hunk ↗ jump to hunk
--- arch/powerpc/include/asm/code-patching.h | 1 + arch/powerpc/lib/code-patching.c | 7 ++++++- arch/powerpc/net/bpf_jit.h | 7 +------ 3 files changed, 8 insertions(+), 7 deletions(-)diff --git a/arch/powerpc/include/asm/code-patching.h b/arch/powerpc/include/asm/code-patching.h index a95f63788c6b14..4ba834599c4d4c 100644 --- a/arch/powerpc/include/asm/code-patching.h +++ b/arch/powerpc/include/asm/code-patching.h@@ -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,diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index f9a3019e37b43c..e2342b9a1ab9c9 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c@@ -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); +}
Why not inline this one?
quoted hunk ↗ jump to hunk
+ /* * 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. */diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index 99fad093f43ec1..935ea95b66359e 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h@@ -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 { \ --2.33.0