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SubjectRe: [PATCH v4 2/5] LoongArch: Use la.pcrel instead of la.abs for exception handlers
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On 02/10/2023 05:09 PM, Huacai Chen wrote:
> Hi, Youling and Ruoyao,
>
> Thank you very much for implementing the per-node exceptions. But I
> want to know if the per-node solution is really worthy for a PIE
> kernel. So, could you please test the performance? Maybe we can reduce
> the complexity if we give up the per-node solution.

I will test performance on NUMA machines based on v2 and v3 patch sets.

Youling.
>
> Huacai
>
> On Fri, Feb 10, 2023 at 4:47 PM Youling Tang <tangyouling@loongson.cn> wrote:
>>
>> From: Xi Ruoyao <xry111@xry111.site>
>>
>> It's needed to build the kernel as a PIE, or the linker will complain.
>>
>> For the consideration about performance, we copy the exception handlers
>> to a dedicated 64 KB area for each CPU. So, the PC-relative offset
>> calculated at link time will be incorrect and we need to relocate the
>> exception handlers after copying them.
>>
>> For the simplicity, we don't use the ELF R_LARCH_* relocations, but code
>> an relocation entry as simply (offset_in_the_handler, symbol_addr). For
>> each exception handler, we also code the number of relocation entries.
>> Then we can use the relocation information to fix up the handlers after
>> copying them.
>>
>> Signed-off-by: Xi Ruoyao <xry111@xry111.site>
>> ---
>> arch/loongarch/include/asm/inst.h | 1 +
>> arch/loongarch/include/asm/setup.h | 6 +-
>> arch/loongarch/include/asm/stackframe.h | 3 +-
>> arch/loongarch/kernel/genex.S | 40 +++++-
>> arch/loongarch/kernel/traps.c | 158 ++++++++++++++++++++----
>> arch/loongarch/mm/tlb.c | 23 ++--
>> arch/loongarch/mm/tlbex.S | 69 +++++++++--
>> 7 files changed, 255 insertions(+), 45 deletions(-)
>>
>> diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
>> index 7eedd83fd0d7..426054518a3d 100644
>> --- a/arch/loongarch/include/asm/inst.h
>> +++ b/arch/loongarch/include/asm/inst.h
>> @@ -32,6 +32,7 @@ enum reg1i20_op {
>> lu12iw_op = 0x0a,
>> lu32id_op = 0x0b,
>> pcaddi_op = 0x0c,
>> + pcalau12i_op = 0x0d,
>> pcaddu12i_op = 0x0e,
>> pcaddu18i_op = 0x0f,
>> };
>> diff --git a/arch/loongarch/include/asm/setup.h b/arch/loongarch/include/asm/setup.h
>> index 72ead58039f3..f0a2b34365f1 100644
>> --- a/arch/loongarch/include/asm/setup.h
>> +++ b/arch/loongarch/include/asm/setup.h
>> @@ -11,6 +11,9 @@
>>
>> #define VECSIZE 0x200
>>
>> +struct handler_reloc;
>> +
>> +extern struct handler_reloc *eentry_reloc[];
>> extern unsigned long eentry;
>> extern unsigned long tlbrentry;
>> extern char init_command_line[COMMAND_LINE_SIZE];
>> @@ -18,7 +21,8 @@ extern void tlb_init(int cpu);
>> extern void cpu_cache_init(void);
>> extern void cache_error_setup(void);
>> extern void per_cpu_trap_init(int cpu);
>> -extern void set_handler(unsigned long offset, void *addr, unsigned long len);
>> +extern void set_handler(unsigned long exccode, void *addr);
>> extern void set_merr_handler(unsigned long offset, void *addr, unsigned long len);
>> +extern void reloc_handler(unsigned long handler, struct handler_reloc *rel);
>>
>> #endif /* __SETUP_H */
>> diff --git a/arch/loongarch/include/asm/stackframe.h b/arch/loongarch/include/asm/stackframe.h
>> index 7deb043ce387..bbec1e56b61b 100644
>> --- a/arch/loongarch/include/asm/stackframe.h
>> +++ b/arch/loongarch/include/asm/stackframe.h
>> @@ -77,7 +77,8 @@
>> * new value in sp.
>> */
>> .macro get_saved_sp docfi=0
>> - la.abs t1, kernelsp
>> + /* The label is used for generating reloc tables for handlers */
>> +514: la.pcrel t1, t0, kernelsp
>> #ifdef CONFIG_SMP
>> csrrd t0, PERCPU_BASE_KS
>> LONG_ADD t1, t1, t0
>> diff --git a/arch/loongarch/kernel/genex.S b/arch/loongarch/kernel/genex.S
>> index 7e5c293ed89f..005a10fe5a50 100644
>> --- a/arch/loongarch/kernel/genex.S
>> +++ b/arch/loongarch/kernel/genex.S
>> @@ -34,7 +34,7 @@ SYM_FUNC_END(__arch_cpu_idle)
>> SYM_FUNC_START(handle_vint)
>> BACKUP_T0T1
>> SAVE_ALL
>> - la.abs t1, __arch_cpu_idle
>> +0: la.pcrel t1, t2, __arch_cpu_idle
>> LONG_L t0, sp, PT_ERA
>> /* 32 byte rollback region */
>> ori t0, t0, 0x1f
>> @@ -43,11 +43,25 @@ SYM_FUNC_START(handle_vint)
>> LONG_S t0, sp, PT_ERA
>> 1: move a0, sp
>> move a1, sp
>> - la.abs t0, do_vint
>> +2: la.pcrel t0, t2, do_vint
>> jirl ra, t0, 0
>> RESTORE_ALL_AND_RET
>> SYM_FUNC_END(handle_vint)
>>
>> +SYM_DATA_START(rel_handle_vint)
>> +LONG 3
>> +
>> +LONG 514b - handle_vint
>> +LONG kernelsp
>> +
>> +LONG 0b - handle_vint
>> +LONG __arch_cpu_idle
>> +
>> +LONG 2b - handle_vint
>> +LONG do_vint
>> +
>> +SYM_DATA_END(rel_handle_vint)
>> +
>> SYM_FUNC_START(except_vec_cex)
>> b cache_parity_error
>> SYM_FUNC_END(except_vec_cex)
>> @@ -72,12 +86,24 @@ SYM_FUNC_END(except_vec_cex)
>> SAVE_ALL
>> build_prep_\prep
>> move a0, sp
>> - la.abs t0, do_\handler
>> + 667:
>> + la.pcrel t0, t1, do_\handler
>> jirl ra, t0, 0
>> 668:
>> RESTORE_ALL_AND_RET
>> SYM_FUNC_END(handle_\exception)
>> SYM_DATA(unwind_hint_\exception, .word 668b - 666b)
>> +
>> + SYM_DATA_START(rel_handle_\exception)
>> + LONG 2
>> +
>> + LONG 514b - 666b
>> + LONG kernelsp
>> +
>> + LONG 667b - 666b
>> + LONG do_\handler
>> +
>> + SYM_DATA_END(rel_handle_\exception)
>> .endm
>>
>> BUILD_HANDLER ade ade badv
>> @@ -93,6 +119,12 @@ SYM_FUNC_END(except_vec_cex)
>> BUILD_HANDLER reserved reserved none /* others */
>>
>> SYM_FUNC_START(handle_sys)
>> - la.abs t0, handle_syscall
>> + la.pcrel t0, t1, handle_syscall
>> jr t0
>> SYM_FUNC_END(handle_sys)
>> +
>> +SYM_DATA_START(rel_handle_sys)
>> +LONG 1
>> +LONG 0
>> +LONG handle_syscall
>> +SYM_DATA_END(rel_handle_sys)
>> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
>> index c38a146a973b..7e073854f493 100644
>> --- a/arch/loongarch/kernel/traps.c
>> +++ b/arch/loongarch/kernel/traps.c
>> @@ -62,6 +62,127 @@ extern asmlinkage void handle_reserved(void);
>> extern asmlinkage void handle_watch(void);
>> extern asmlinkage void handle_vint(void);
>>
>> +struct handler_reloc_entry {
>> + unsigned long offset;
>> + unsigned long sym;
>> +};
>> +
>> +struct handler_reloc {
>> + unsigned long cnt;
>> + struct handler_reloc_entry entries[];
>> +};
>> +
>> +extern struct handler_reloc rel_handle_tlb_load;
>> +extern struct handler_reloc rel_handle_tlb_store;
>> +extern struct handler_reloc rel_handle_tlb_modify;
>> +extern struct handler_reloc rel_handle_tlb_protect;
>> +extern struct handler_reloc rel_handle_ade;
>> +extern struct handler_reloc rel_handle_ale;
>> +extern struct handler_reloc rel_handle_sys;
>> +extern struct handler_reloc rel_handle_bp;
>> +extern struct handler_reloc rel_handle_ri;
>> +extern struct handler_reloc rel_handle_fpu;
>> +extern struct handler_reloc rel_handle_lsx;
>> +extern struct handler_reloc rel_handle_lasx;
>> +extern struct handler_reloc rel_handle_fpe;
>> +extern struct handler_reloc rel_handle_lbt;
>> +extern struct handler_reloc rel_handle_watch;
>> +extern struct handler_reloc rel_handle_reserved;
>> +extern struct handler_reloc rel_handle_vint;
>> +
>> +struct handler_reloc *eentry_reloc[128] = {
>> + [0] = NULL, /* merr handler */
>> + [EXCCODE_TLBL] = &rel_handle_tlb_load,
>> + [EXCCODE_TLBS] = &rel_handle_tlb_store,
>> + [EXCCODE_TLBI] = &rel_handle_tlb_load,
>> + [EXCCODE_TLBM] = &rel_handle_tlb_modify,
>> + [EXCCODE_TLBNR] = &rel_handle_tlb_protect,
>> + [EXCCODE_TLBNX] = &rel_handle_tlb_protect,
>> + [EXCCODE_TLBPE] = &rel_handle_tlb_protect,
>> + [EXCCODE_ADE] = &rel_handle_ade,
>> + [EXCCODE_ALE] = &rel_handle_ale,
>> + [EXCCODE_SYS] = &rel_handle_sys,
>> + [EXCCODE_BP] = &rel_handle_bp,
>> + [EXCCODE_INE] = &rel_handle_ri,
>> + [EXCCODE_IPE] = &rel_handle_ri,
>> + [EXCCODE_FPDIS] = &rel_handle_fpu,
>> + [EXCCODE_LSXDIS] = &rel_handle_lsx,
>> + [EXCCODE_LASXDIS] = &rel_handle_lasx,
>> + [EXCCODE_FPE] = &rel_handle_fpe,
>> + [EXCCODE_BTDIS] = &rel_handle_lbt,
>> + [EXCCODE_WATCH] = &rel_handle_watch,
>> + [(EXCCODE_WATCH + 1) ... (EXCCODE_INT_START - 1)] = &rel_handle_reserved,
>> + [EXCCODE_INT_START ... (EXCCODE_INT_END - 1)] = &rel_handle_vint,
>> +};
>> +
>> +void reloc_handler(unsigned long handler, struct handler_reloc *rel)
>> +{
>> + if (!rel)
>> + return;
>> +
>> + for (unsigned long i = 0; i < rel->cnt; i++) {
>> + unsigned long pc = handler + rel->entries[i].offset;
>> + union loongarch_instruction *insn =
>> + (union loongarch_instruction *)pc;
>> + u32 imm[4];
>> + unsigned long v = rel->entries[i].sym;
>> +
>> + /* GNU as >= 2.40 uses pcalau12i for la.pcrel, but GNU ld <= 2.39
>> + * uses pcaddu12i.
>> + */
>> + if (insn->reg1i20_format.opcode == pcalau12i_op) {
>> + /* Use s32 deliberately for sign extension. */
>> + s32 offset_hi20 = ((v + 0x800) & ~0xfff) -
>> + (pc & ~0xfff);
>> + unsigned long anchor = (pc & ~0xfff) + offset_hi20;
>> + unsigned long offset_rem = v - anchor;
>> +
>> + imm[0] = (offset_hi20 >> 12) & 0xfffff;
>> + imm[1] = v & 0xfff;
>> + imm[2] = (offset_rem >> 32) & 0xfffff;
>> + imm[3] = offset_rem >> 52;
>> + } else if (insn->reg1i20_format.opcode == pcaddu12i_op) {
>> + /* Use s32 deliberately for sign extension. */
>> + s32 offset_lo = v - pc;
>> + unsigned long offset_hi = v - pc - offset_lo;
>> +
>> + imm[0] = (offset_lo >> 12) & 0xfffff;
>> + imm[1] = offset_lo & 0xfff;
>> + imm[2] = (offset_hi >> 32) & 0xfffff;
>> + imm[3] = offset_hi >> 52;
>> + } else
>> + panic("Cannot fixup la.pcrel for exception handler at %lu: unexpected instruction %d!",
>> + pc, insn->word);
>> +
>> + insn[0].reg1i20_format.immediate = imm[0];
>> + insn[1].reg2i12_format.immediate = imm[1];
>> + insn[2].reg1i20_format.immediate = imm[2];
>> + insn[3].reg2i12_format.immediate = imm[3];
>> + }
>> +}
>> +
>> +/* Install CPU exception handler */
>> +static void do_set_handler(unsigned long exccode, void *addr,
>> + struct handler_reloc *rel)
>> +{
>> + unsigned long dest_addr = eentry + exccode * VECSIZE;
>> +
>> + memcpy((void *)dest_addr, addr, VECSIZE);
>> + reloc_handler(dest_addr, rel);
>> + local_flush_icache_range(dest_addr, dest_addr + VECSIZE);
>> +}
>> +
>> +/* Install CPU exception handler, with the reloc table from eentry_reloc */
>> +void set_handler(unsigned long exccode, void *addr)
>> +{
>> + do_set_handler(exccode, addr, eentry_reloc[exccode]);
>> +}
>> +
>> +static void set_handler_reserved(unsigned long exccode)
>> +{
>> + do_set_handler(exccode, handle_reserved, &rel_handle_reserved);
>> +}
>> +
>> static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
>> const char *loglvl, bool user)
>> {
>> @@ -704,19 +825,12 @@ void per_cpu_trap_init(int cpu)
>> /* Initialise exception handlers */
>> if (cpu == 0)
>> for (i = 0; i < 64; i++)
>> - set_handler(i * VECSIZE, handle_reserved, VECSIZE);
>> + set_handler_reserved(i);
>>
>> tlb_init(cpu);
>> cpu_cache_init();
>> }
>>
>> -/* Install CPU exception handler */
>> -void set_handler(unsigned long offset, void *addr, unsigned long size)
>> -{
>> - memcpy((void *)(eentry + offset), addr, size);
>> - local_flush_icache_range(eentry + offset, eentry + offset + size);
>> -}
>> -
>> static const char panic_null_cerr[] =
>> "Trying to set NULL cache error exception handler\n";
>>
>> @@ -741,20 +855,20 @@ void __init trap_init(void)
>>
>> /* Set interrupt vector handler */
>> for (i = EXCCODE_INT_START; i < EXCCODE_INT_END; i++)
>> - set_handler(i * VECSIZE, handle_vint, VECSIZE);
>> -
>> - set_handler(EXCCODE_ADE * VECSIZE, handle_ade, VECSIZE);
>> - set_handler(EXCCODE_ALE * VECSIZE, handle_ale, VECSIZE);
>> - set_handler(EXCCODE_SYS * VECSIZE, handle_sys, VECSIZE);
>> - set_handler(EXCCODE_BP * VECSIZE, handle_bp, VECSIZE);
>> - set_handler(EXCCODE_INE * VECSIZE, handle_ri, VECSIZE);
>> - set_handler(EXCCODE_IPE * VECSIZE, handle_ri, VECSIZE);
>> - set_handler(EXCCODE_FPDIS * VECSIZE, handle_fpu, VECSIZE);
>> - set_handler(EXCCODE_LSXDIS * VECSIZE, handle_lsx, VECSIZE);
>> - set_handler(EXCCODE_LASXDIS * VECSIZE, handle_lasx, VECSIZE);
>> - set_handler(EXCCODE_FPE * VECSIZE, handle_fpe, VECSIZE);
>> - set_handler(EXCCODE_BTDIS * VECSIZE, handle_lbt, VECSIZE);
>> - set_handler(EXCCODE_WATCH * VECSIZE, handle_watch, VECSIZE);
>> + set_handler(i, handle_vint);
>> +
>> + set_handler(EXCCODE_ADE, handle_ade);
>> + set_handler(EXCCODE_ALE, handle_ale);
>> + set_handler(EXCCODE_SYS, handle_sys);
>> + set_handler(EXCCODE_BP, handle_bp);
>> + set_handler(EXCCODE_INE, handle_ri);
>> + set_handler(EXCCODE_IPE, handle_ri);
>> + set_handler(EXCCODE_FPDIS, handle_fpu);
>> + set_handler(EXCCODE_LSXDIS, handle_lsx);
>> + set_handler(EXCCODE_LASXDIS, handle_lasx);
>> + set_handler(EXCCODE_FPE, handle_fpe);
>> + set_handler(EXCCODE_BTDIS, handle_lbt);
>> + set_handler(EXCCODE_WATCH, handle_watch);
>>
>> cache_error_setup();
>>
>> diff --git a/arch/loongarch/mm/tlb.c b/arch/loongarch/mm/tlb.c
>> index 8bad6b0cff59..6f70aab7202a 100644
>> --- a/arch/loongarch/mm/tlb.c
>> +++ b/arch/loongarch/mm/tlb.c
>> @@ -253,7 +253,6 @@ static void output_pgtable_bits_defines(void)
>> #ifdef CONFIG_NUMA
>> unsigned long pcpu_handlers[NR_CPUS];
>> #endif
>> -extern long exception_handlers[VECSIZE * 128 / sizeof(long)];
>>
>> void setup_tlb_handler(int cpu)
>> {
>> @@ -264,19 +263,20 @@ void setup_tlb_handler(int cpu)
>> if (cpu == 0) {
>> memcpy((void *)tlbrentry, handle_tlb_refill, 0x80);
>> local_flush_icache_range(tlbrentry, tlbrentry + 0x80);
>> - set_handler(EXCCODE_TLBI * VECSIZE, handle_tlb_load, VECSIZE);
>> - set_handler(EXCCODE_TLBL * VECSIZE, handle_tlb_load, VECSIZE);
>> - set_handler(EXCCODE_TLBS * VECSIZE, handle_tlb_store, VECSIZE);
>> - set_handler(EXCCODE_TLBM * VECSIZE, handle_tlb_modify, VECSIZE);
>> - set_handler(EXCCODE_TLBNR * VECSIZE, handle_tlb_protect, VECSIZE);
>> - set_handler(EXCCODE_TLBNX * VECSIZE, handle_tlb_protect, VECSIZE);
>> - set_handler(EXCCODE_TLBPE * VECSIZE, handle_tlb_protect, VECSIZE);
>> + set_handler(EXCCODE_TLBI, handle_tlb_load);
>> + set_handler(EXCCODE_TLBL, handle_tlb_load);
>> + set_handler(EXCCODE_TLBS, handle_tlb_store);
>> + set_handler(EXCCODE_TLBM, handle_tlb_modify);
>> + set_handler(EXCCODE_TLBNR, handle_tlb_protect);
>> + set_handler(EXCCODE_TLBNX, handle_tlb_protect);
>> + set_handler(EXCCODE_TLBPE, handle_tlb_protect);
>> }
>> #ifdef CONFIG_NUMA
>> else {
>> void *addr;
>> + unsigned long addr_ul;
>> struct page *page;
>> - const int vec_sz = sizeof(exception_handlers);
>> + const int vec_sz = VECSIZE * 128;
>>
>> if (pcpu_handlers[cpu])
>> return;
>> @@ -286,8 +286,11 @@ void setup_tlb_handler(int cpu)
>> return;
>>
>> addr = page_address(page);
>> + addr_ul = (unsigned long)addr;
>> pcpu_handlers[cpu] = (unsigned long)addr;
>> - memcpy((void *)addr, (void *)eentry, vec_sz);
>> + memcpy(addr, (void *)eentry, vec_sz);
>> + for (unsigned long i = 0; i < 128; i++)
>> + reloc_handler(addr_ul + i * VECSIZE, eentry_reloc[i]);
>> local_flush_icache_range((unsigned long)addr, (unsigned long)addr + vec_sz);
>> csr_write64(pcpu_handlers[cpu], LOONGARCH_CSR_EENTRY);
>> csr_write64(pcpu_handlers[cpu], LOONGARCH_CSR_MERRENTRY);
>> diff --git a/arch/loongarch/mm/tlbex.S b/arch/loongarch/mm/tlbex.S
>> index 3dd2a9615cd9..044c2190771a 100644
>> --- a/arch/loongarch/mm/tlbex.S
>> +++ b/arch/loongarch/mm/tlbex.S
>> @@ -39,11 +39,21 @@ SYM_FUNC_START(handle_tlb_protect)
>> move a1, zero
>> csrrd a2, LOONGARCH_CSR_BADV
>> REG_S a2, sp, PT_BVADDR
>> - la.abs t0, do_page_fault
>> +1: la.pcrel t0, t1, do_page_fault
>> jirl ra, t0, 0
>> RESTORE_ALL_AND_RET
>> SYM_FUNC_END(handle_tlb_protect)
>>
>> +SYM_DATA_START(rel_handle_tlb_protect)
>> + LONG 2
>> +
>> + LONG 514b - handle_tlb_protect
>> + LONG kernelsp
>> +
>> + LONG 1b - handle_tlb_protect
>> + LONG do_page_fault
>> +SYM_DATA_END(rel_handle_tlb_protect)
>> +
>> SYM_FUNC_START(handle_tlb_load)
>> csrwr t0, EXCEPTION_KS0
>> csrwr t1, EXCEPTION_KS1
>> @@ -115,7 +125,8 @@ smp_pgtable_change_load:
>>
>> #ifdef CONFIG_64BIT
>> vmalloc_load:
>> - la.abs t1, swapper_pg_dir
>> + /* The first insn of vmalloc_done_load overwrites ra */
>> +1: la.pcrel t1, ra, swapper_pg_dir
>> b vmalloc_done_load
>> #endif
>>
>> @@ -186,10 +197,24 @@ tlb_huge_update_load:
>> nopage_tlb_load:
>> dbar 0
>> csrrd ra, EXCEPTION_KS2
>> - la.abs t0, tlb_do_page_fault_0
>> +2: la.pcrel t0, t1, tlb_do_page_fault_0
>> jr t0
>> SYM_FUNC_END(handle_tlb_load)
>>
>> +SYM_DATA_START(rel_handle_tlb_load)
>> +#ifdef CONFIG_64BIT
>> + LONG 2
>> +
>> + LONG 1b - handle_tlb_load
>> + LONG swapper_pg_dir
>> +#else
>> + LONG 1
>> +#endif
>> +
>> + LONG 2b - handle_tlb_load
>> + LONG tlb_do_page_fault_0
>> +SYM_DATA_END(rel_handle_tlb_load)
>> +
>> SYM_FUNC_START(handle_tlb_store)
>> csrwr t0, EXCEPTION_KS0
>> csrwr t1, EXCEPTION_KS1
>> @@ -262,7 +287,8 @@ smp_pgtable_change_store:
>>
>> #ifdef CONFIG_64BIT
>> vmalloc_store:
>> - la.abs t1, swapper_pg_dir
>> + /* The first insn of vmalloc_done_store overwrites ra */
>> +1: la.pcrel t1, ra, swapper_pg_dir
>> b vmalloc_done_store
>> #endif
>>
>> @@ -335,10 +361,24 @@ tlb_huge_update_store:
>> nopage_tlb_store:
>> dbar 0
>> csrrd ra, EXCEPTION_KS2
>> - la.abs t0, tlb_do_page_fault_1
>> +2: la.pcrel t0, t1, tlb_do_page_fault_1
>> jr t0
>> SYM_FUNC_END(handle_tlb_store)
>>
>> +SYM_DATA_START(rel_handle_tlb_store)
>> +#ifdef CONFIG_64BIT
>> + LONG 2
>> +
>> + LONG 1b - handle_tlb_store
>> + LONG swapper_pg_dir
>> +#else
>> + LONG 1
>> +#endif
>> +
>> + LONG 2b - handle_tlb_store
>> + LONG tlb_do_page_fault_1
>> +SYM_DATA_END(rel_handle_tlb_store)
>> +
>> SYM_FUNC_START(handle_tlb_modify)
>> csrwr t0, EXCEPTION_KS0
>> csrwr t1, EXCEPTION_KS1
>> @@ -410,7 +450,8 @@ smp_pgtable_change_modify:
>>
>> #ifdef CONFIG_64BIT
>> vmalloc_modify:
>> - la.abs t1, swapper_pg_dir
>> + /* The first insn of vmalloc_done_modify overwrites ra */
>> +1: la.pcrel t1, ra, swapper_pg_dir
>> b vmalloc_done_modify
>> #endif
>>
>> @@ -482,10 +523,24 @@ tlb_huge_update_modify:
>> nopage_tlb_modify:
>> dbar 0
>> csrrd ra, EXCEPTION_KS2
>> - la.abs t0, tlb_do_page_fault_1
>> +2: la.pcrel t0, t1, tlb_do_page_fault_1
>> jr t0
>> SYM_FUNC_END(handle_tlb_modify)
>>
>> +SYM_DATA_START(rel_handle_tlb_modify)
>> +#ifdef CONFIG_64BIT
>> + LONG 2
>> +
>> + LONG 1b - handle_tlb_modify
>> + LONG swapper_pg_dir
>> +#else
>> + LONG 1
>> +#endif
>> +
>> + LONG 2b - handle_tlb_modify
>> + LONG tlb_do_page_fault_1
>> +SYM_DATA_END(rel_handle_tlb_modify)
>> +
>> SYM_FUNC_START(handle_tlb_refill)
>> csrwr t0, LOONGARCH_CSR_TLBRSAVE
>> csrrd t0, LOONGARCH_CSR_PGD
>> --
>> 2.37.3
>>

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