158 lines
4.5 KiB
C
158 lines
4.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/kernel.h>
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#include <linux/jump_label.h>
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#include "asm/cacheflush.h"
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#define JUMPLABEL_ERR "ARC: jump_label: ERROR: "
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/* Halt system on fatal error to make debug easier */
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#define arc_jl_fatal(format...) \
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({ \
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pr_err(JUMPLABEL_ERR format); \
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BUG(); \
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})
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static inline u32 arc_gen_nop(void)
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{
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/* 1x 32bit NOP in middle endian */
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return 0x7000264a;
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}
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/*
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* Atomic update of patched instruction is only available if this
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* instruction doesn't cross L1 cache line boundary. You can read about
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* the way we achieve this in arc/include/asm/jump_label.h
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*/
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static inline void instruction_align_assert(void *addr, int len)
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{
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unsigned long a = (unsigned long)addr;
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if ((a >> L1_CACHE_SHIFT) != ((a + len - 1) >> L1_CACHE_SHIFT))
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arc_jl_fatal("instruction (addr %px) cross L1 cache line border",
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addr);
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}
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/*
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* ARCv2 'Branch unconditionally' instruction:
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* 00000ssssssssss1SSSSSSSSSSNRtttt
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* s S[n:0] lower bits signed immediate (number is bitfield size)
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* S S[m:n+1] upper bits signed immediate (number is bitfield size)
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* t S[24:21] upper bits signed immediate (branch unconditionally far)
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* N N <.d> delay slot mode
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* R R Reserved
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*/
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static inline u32 arc_gen_branch(jump_label_t pc, jump_label_t target)
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{
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u32 instruction_l, instruction_r;
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u32 pcl = pc & GENMASK(31, 2);
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u32 u_offset = target - pcl;
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u32 s, S, t;
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/*
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* Offset in 32-bit branch instruction must to fit into s25.
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* Something is terribly broken if we get such huge offset within one
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* function.
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*/
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if ((s32)u_offset < -16777216 || (s32)u_offset > 16777214)
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arc_jl_fatal("gen branch with offset (%d) not fit in s25",
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(s32)u_offset);
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/*
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* All instructions are aligned by 2 bytes so we should never get offset
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* here which is not 2 bytes aligned.
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*/
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if (u_offset & 0x1)
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arc_jl_fatal("gen branch with offset (%d) unaligned to 2 bytes",
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(s32)u_offset);
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s = (u_offset >> 1) & GENMASK(9, 0);
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S = (u_offset >> 11) & GENMASK(9, 0);
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t = (u_offset >> 21) & GENMASK(3, 0);
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/* 00000ssssssssss1 */
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instruction_l = (s << 1) | 0x1;
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/* SSSSSSSSSSNRtttt */
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instruction_r = (S << 6) | t;
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return (instruction_r << 16) | (instruction_l & GENMASK(15, 0));
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}
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void arch_jump_label_transform(struct jump_entry *entry,
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enum jump_label_type type)
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{
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jump_label_t *instr_addr = (jump_label_t *)entry->code;
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u32 instr;
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instruction_align_assert(instr_addr, JUMP_LABEL_NOP_SIZE);
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if (type == JUMP_LABEL_JMP)
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instr = arc_gen_branch(entry->code, entry->target);
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else
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instr = arc_gen_nop();
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WRITE_ONCE(*instr_addr, instr);
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flush_icache_range(entry->code, entry->code + JUMP_LABEL_NOP_SIZE);
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}
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#ifdef CONFIG_ARC_DBG_JUMP_LABEL
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#define SELFTEST_MSG "ARC: instruction generation self-test: "
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struct arc_gen_branch_testdata {
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jump_label_t pc;
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jump_label_t target_address;
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u32 expected_instr;
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};
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static __init int branch_gen_test(const struct arc_gen_branch_testdata *test)
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{
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u32 instr_got;
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instr_got = arc_gen_branch(test->pc, test->target_address);
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if (instr_got == test->expected_instr)
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return 0;
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pr_err(SELFTEST_MSG "FAIL:\n arc_gen_branch(0x%08x, 0x%08x) != 0x%08x, got 0x%08x\n",
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test->pc, test->target_address,
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test->expected_instr, instr_got);
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return -EFAULT;
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}
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/*
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* Offset field in branch instruction is not continuous. Test all
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* available offset field and sign combinations. Test data is generated
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* from real working code.
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*/
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static const struct arc_gen_branch_testdata arcgenbr_test_data[] __initconst = {
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{0x90007548, 0x90007514, 0xffcf07cd}, /* tiny (-52) offs */
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{0x9000c9c0, 0x9000c782, 0xffcf05c3}, /* tiny (-574) offs */
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{0x9000cc1c, 0x9000c782, 0xffcf0367}, /* tiny (-1178) offs */
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{0x9009dce0, 0x9009d106, 0xff8f0427}, /* small (-3034) offs */
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{0x9000f5de, 0x90007d30, 0xfc0f0755}, /* big (-30892) offs */
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{0x900a2444, 0x90035f64, 0xc9cf0321}, /* huge (-443616) offs */
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{0x90007514, 0x9000752c, 0x00000019}, /* tiny (+24) offs */
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{0x9001a578, 0x9001a77a, 0x00000203}, /* tiny (+514) offs */
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{0x90031ed8, 0x90032634, 0x0000075d}, /* tiny (+1884) offs */
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{0x9008c7f2, 0x9008d3f0, 0x00400401}, /* small (+3072) offs */
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{0x9000bb38, 0x9003b340, 0x17c00009}, /* big (+194568) offs */
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{0x90008f44, 0x90578d80, 0xb7c2063d} /* huge (+5701180) offs */
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};
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static __init int instr_gen_test(void)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(arcgenbr_test_data); i++)
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if (branch_gen_test(&arcgenbr_test_data[i]))
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return -EFAULT;
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pr_info(SELFTEST_MSG "OK\n");
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return 0;
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}
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early_initcall(instr_gen_test);
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#endif /* CONFIG_ARC_DBG_JUMP_LABEL */
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