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Message-ID: <6f1a1f3c-4569-c427-76ae-2f7093cb5e9f@loongson.cn>
Date: Sat, 14 Jan 2023 14:38:01 +0800
From: Jinyang He <hejinyang@...ngson.cn>
To: Youling Tang <tangyouling@...ngson.cn>,
Huacai Chen <chenhuacai@...nel.org>,
Xi Ruoyao <xry111@...111.site>
Cc: Xuerui Wang <kernel@...0n.name>, loongarch@...ts.linux.dev,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] LoongArch: Use trampoline for exception handlers and
kill la.abs
Hi, Ruoyao and Youling,
I care about the performance when NUMA enabled. We set CSR.EENTRY
for each possible cpus where is NUMA-relative. So, I guess the more
codes in NUMA-relative memory makes more performance. If we just set
handler_trampoline as exception handler, the performance may be
influenced.
Thanks,
Jinyang
On 2023-01-09 17:07, Youling Tang wrote:
> From: Xi Ruoyao <xry111@...111.site>
>
> Use a trampoline as an exception handlers, which can kill some use of
> la.abs in preparation for the subsequent support of the PIE kernel.
>
> Signed-off-by: Xi Ruoyao <xry111@...111.site>
> Signed-off-by: Youling Tang <tangyouling@...ngson.cn>
> ---
> arch/loongarch/include/asm/stackframe.h | 8 +++----
> arch/loongarch/include/asm/uaccess.h | 1 -
> arch/loongarch/kernel/entry.S | 6 +++---
> arch/loongarch/kernel/genex.S | 20 +++++++++---------
> arch/loongarch/kernel/head.S | 2 +-
> arch/loongarch/kernel/traps.c | 4 +++-
> arch/loongarch/mm/tlbex.S | 28 +++++++------------------
> 7 files changed, 29 insertions(+), 40 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/stackframe.h b/arch/loongarch/include/asm/stackframe.h
> index 4ca953062b5b..96c94035b5d0 100644
> --- a/arch/loongarch/include/asm/stackframe.h
> +++ b/arch/loongarch/include/asm/stackframe.h
> @@ -76,8 +76,8 @@
> * kernelsp array for it. It stores the current sp in t0 and loads the
> * new value in sp.
> */
> - .macro get_saved_sp docfi=0
> - la.abs t1, kernelsp
> + .macro get_saved_sp docfi=0
> + la.pcrel t1, kernelsp
> #ifdef CONFIG_SMP
> csrrd t0, PERCPU_BASE_KS
> LONG_ADD t1, t1, t0
> @@ -89,8 +89,8 @@
> LONG_L sp, t1, 0
> .endm
>
> - .macro set_saved_sp stackp temp temp2
> - la.abs \temp, kernelsp
> + .macro set_saved_sp stackp temp temp2
> + la.pcrel \temp, kernelsp
> #ifdef CONFIG_SMP
> LONG_ADD \temp, \temp, u0
> #endif
> diff --git a/arch/loongarch/include/asm/uaccess.h b/arch/loongarch/include/asm/uaccess.h
> index 255899d4a7c3..0d22991ae430 100644
> --- a/arch/loongarch/include/asm/uaccess.h
> +++ b/arch/loongarch/include/asm/uaccess.h
> @@ -22,7 +22,6 @@
> extern u64 __ua_limit;
>
> #define __UA_ADDR ".dword"
> -#define __UA_LA "la.abs"
> #define __UA_LIMIT __ua_limit
>
> /*
> diff --git a/arch/loongarch/kernel/entry.S b/arch/loongarch/kernel/entry.S
> index d53b631c9022..ca01afdbec3f 100644
> --- a/arch/loongarch/kernel/entry.S
> +++ b/arch/loongarch/kernel/entry.S
> @@ -18,9 +18,9 @@
> .text
> .cfi_sections .debug_frame
> .align 5
> -SYM_FUNC_START(handle_syscall)
> +SYM_FUNC_START(handle_sys)
> csrrd t0, PERCPU_BASE_KS
> - la.abs t1, kernelsp
> + la.pcrel t1, kernelsp
> add.d t1, t1, t0
> move t2, sp
> ld.d sp, t1, 0
> @@ -66,7 +66,7 @@ SYM_FUNC_START(handle_syscall)
> bl do_syscall
>
> RESTORE_ALL_AND_RET
> -SYM_FUNC_END(handle_syscall)
> +SYM_FUNC_END(handle_sys)
>
> SYM_CODE_START(ret_from_fork)
> bl schedule_tail # a0 = struct task_struct *prev
> diff --git a/arch/loongarch/kernel/genex.S b/arch/loongarch/kernel/genex.S
> index 75e5be807a0d..d3df0fa725a2 100644
> --- a/arch/loongarch/kernel/genex.S
> +++ b/arch/loongarch/kernel/genex.S
> @@ -32,9 +32,8 @@ SYM_FUNC_START(__arch_cpu_idle)
> SYM_FUNC_END(__arch_cpu_idle)
>
> SYM_FUNC_START(handle_vint)
> - BACKUP_T0T1
> SAVE_ALL
> - la.abs t1, __arch_cpu_idle
> + la.pcrel t1, __arch_cpu_idle
> LONG_L t0, sp, PT_ERA
> /* 32 byte rollback region */
> ori t0, t0, 0x1f
> @@ -43,8 +42,7 @@ SYM_FUNC_START(handle_vint)
> LONG_S t0, sp, PT_ERA
> 1: move a0, sp
> move a1, sp
> - la.abs t0, do_vint
> - jirl ra, t0, 0
> + bl do_vint
> RESTORE_ALL_AND_RET
> SYM_FUNC_END(handle_vint)
>
> @@ -67,12 +65,10 @@ SYM_FUNC_END(except_vec_cex)
> .macro BUILD_HANDLER exception handler prep
> .align 5
> SYM_FUNC_START(handle_\exception)
> - BACKUP_T0T1
> SAVE_ALL
> build_prep_\prep
> move a0, sp
> - la.abs t0, do_\handler
> - jirl ra, t0, 0
> + bl do_\handler
> RESTORE_ALL_AND_RET
> SYM_FUNC_END(handle_\exception)
> .endm
> @@ -89,7 +85,11 @@ SYM_FUNC_END(except_vec_cex)
> BUILD_HANDLER watch watch none
> BUILD_HANDLER reserved reserved none /* others */
>
> -SYM_FUNC_START(handle_sys)
> - la.abs t0, handle_syscall
> +SYM_FUNC_START(handler_trampoline)
> + csrwr t0, EXCEPTION_KS0
> + csrwr t1, EXCEPTION_KS1
> + pcaddi t0, 0
> + ld.d t0, t0, 16
> jr t0
> -SYM_FUNC_END(handle_sys)
> + nop
> +SYM_FUNC_END(handler_trampoline)
> diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
> index 57bada6b4e93..aa6181714ec3 100644
> --- a/arch/loongarch/kernel/head.S
> +++ b/arch/loongarch/kernel/head.S
> @@ -117,7 +117,7 @@ SYM_CODE_START(smpboot_entry)
> li.w t0, 0x00 # FPE=0, SXE=0, ASXE=0, BTE=0
> csrwr t0, LOONGARCH_CSR_EUEN
>
> - la.abs t0, cpuboot_data
> + la.pcrel t0, cpuboot_data
> ld.d sp, t0, CPU_BOOT_STACK
> ld.d tp, t0, CPU_BOOT_TINFO
>
> diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
> index 7ea62faeeadb..0e8faaca3679 100644
> --- a/arch/loongarch/kernel/traps.c
> +++ b/arch/loongarch/kernel/traps.c
> @@ -61,6 +61,7 @@ extern asmlinkage void handle_lasx(void);
> extern asmlinkage void handle_reserved(void);
> extern asmlinkage void handle_watch(void);
> extern asmlinkage void handle_vint(void);
> +extern asmlinkage void handler_trampoline(void);
>
> static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
> const char *loglvl, bool user)
> @@ -716,7 +717,8 @@ void per_cpu_trap_init(int cpu)
> /* Install CPU exception handler */
> void set_handler(unsigned long offset, void *addr, unsigned long size)
> {
> - memcpy((void *)(eentry + offset), addr, size);
> + memcpy((void *)(eentry + offset), &handler_trampoline, 24);
> + memcpy((void *)(eentry + offset + 24), &addr, 8);
> local_flush_icache_range(eentry + offset, eentry + offset + size);
> }
>
> diff --git a/arch/loongarch/mm/tlbex.S b/arch/loongarch/mm/tlbex.S
> index 58781c6e4191..cfaacdac518c 100644
> --- a/arch/loongarch/mm/tlbex.S
> +++ b/arch/loongarch/mm/tlbex.S
> @@ -24,8 +24,7 @@
> move a0, sp
> REG_S a2, sp, PT_BVADDR
> li.w a1, \write
> - la.abs t0, do_page_fault
> - jirl ra, t0, 0
> + bl do_page_fault
> RESTORE_ALL_AND_RET
> SYM_FUNC_END(tlb_do_page_fault_\write)
> .endm
> @@ -34,20 +33,16 @@
> tlb_do_page_fault 1
>
> SYM_FUNC_START(handle_tlb_protect)
> - BACKUP_T0T1
> SAVE_ALL
> move a0, sp
> move a1, zero
> csrrd a2, LOONGARCH_CSR_BADV
> REG_S a2, sp, PT_BVADDR
> - la.abs t0, do_page_fault
> - jirl ra, t0, 0
> + bl do_page_fault
> RESTORE_ALL_AND_RET
> SYM_FUNC_END(handle_tlb_protect)
>
> SYM_FUNC_START(handle_tlb_load)
> - csrwr t0, EXCEPTION_KS0
> - csrwr t1, EXCEPTION_KS1
> csrwr ra, EXCEPTION_KS2
>
> /*
> @@ -116,7 +111,7 @@ smp_pgtable_change_load:
>
> #ifdef CONFIG_64BIT
> vmalloc_load:
> - la.abs t1, swapper_pg_dir
> + la.pcrel t1, swapper_pg_dir
> b vmalloc_done_load
> #endif
>
> @@ -187,13 +182,10 @@ tlb_huge_update_load:
> nopage_tlb_load:
> dbar 0
> csrrd ra, EXCEPTION_KS2
> - la.abs t0, tlb_do_page_fault_0
> - jr t0
> + b tlb_do_page_fault_0
> SYM_FUNC_END(handle_tlb_load)
>
> SYM_FUNC_START(handle_tlb_store)
> - csrwr t0, EXCEPTION_KS0
> - csrwr t1, EXCEPTION_KS1
> csrwr ra, EXCEPTION_KS2
>
> /*
> @@ -263,7 +255,7 @@ smp_pgtable_change_store:
>
> #ifdef CONFIG_64BIT
> vmalloc_store:
> - la.abs t1, swapper_pg_dir
> + la.pcrel t1, swapper_pg_dir
> b vmalloc_done_store
> #endif
>
> @@ -336,13 +328,10 @@ tlb_huge_update_store:
> nopage_tlb_store:
> dbar 0
> csrrd ra, EXCEPTION_KS2
> - la.abs t0, tlb_do_page_fault_1
> - jr t0
> + b tlb_do_page_fault_1
> SYM_FUNC_END(handle_tlb_store)
>
> SYM_FUNC_START(handle_tlb_modify)
> - csrwr t0, EXCEPTION_KS0
> - csrwr t1, EXCEPTION_KS1
> csrwr ra, EXCEPTION_KS2
>
> /*
> @@ -411,7 +400,7 @@ smp_pgtable_change_modify:
>
> #ifdef CONFIG_64BIT
> vmalloc_modify:
> - la.abs t1, swapper_pg_dir
> + la.pcrel t1, swapper_pg_dir
> b vmalloc_done_modify
> #endif
>
> @@ -483,8 +472,7 @@ tlb_huge_update_modify:
> nopage_tlb_modify:
> dbar 0
> csrrd ra, EXCEPTION_KS2
> - la.abs t0, tlb_do_page_fault_1
> - jr t0
> + b tlb_do_page_fault_1
> SYM_FUNC_END(handle_tlb_modify)
>
> SYM_FUNC_START(handle_tlb_refill)
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