From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- arch/alpha/lib/stacktrace.c | 103 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 103 insertions(+) create mode 100644 arch/alpha/lib/stacktrace.c (limited to 'arch/alpha/lib/stacktrace.c') diff --git a/arch/alpha/lib/stacktrace.c b/arch/alpha/lib/stacktrace.c new file mode 100644 index 000000000..2b1176dd5 --- /dev/null +++ b/arch/alpha/lib/stacktrace.c @@ -0,0 +1,103 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +typedef unsigned int instr; + +#define MAJOR_OP 0xfc000000 +#define LDA_OP 0x20000000 +#define STQ_OP 0xb4000000 +#define BR_OP 0xc0000000 + +#define STK_ALLOC_1 0x23de8000 /* lda $30,-X($30) */ +#define STK_ALLOC_1M 0xffff8000 +#define STK_ALLOC_2 0x43c0153e /* subq $30,X,$30 */ +#define STK_ALLOC_2M 0xffe01fff + +#define MEM_REG 0x03e00000 +#define MEM_BASE 0x001f0000 +#define MEM_OFF 0x0000ffff +#define MEM_OFF_SIGN 0x00008000 +#define BASE_SP 0x001e0000 + +#define STK_ALLOC_MATCH(INSTR) \ + (((INSTR) & STK_ALLOC_1M) == STK_ALLOC_1 \ + || ((INSTR) & STK_ALLOC_2M) == STK_ALLOC_2) +#define STK_PUSH_MATCH(INSTR) \ + (((INSTR) & (MAJOR_OP | MEM_BASE | MEM_OFF_SIGN)) == (STQ_OP | BASE_SP)) +#define MEM_OP_OFFSET(INSTR) \ + (((long)((INSTR) & MEM_OFF) << 48) >> 48) +#define MEM_OP_REG(INSTR) \ + (((INSTR) & MEM_REG) >> 22) + +/* Branches, jumps, PAL calls, and illegal opcodes end a basic block. */ +#define BB_END(INSTR) \ + (((instr)(INSTR) >= BR_OP) | ((instr)(INSTR) < LDA_OP) | \ + ((((instr)(INSTR) ^ 0x60000000) < 0x20000000) & \ + (((instr)(INSTR) & 0x0c000000) != 0))) + +#define IS_KERNEL_TEXT(PC) ((unsigned long)(PC) > START_ADDR) + +static char reg_name[][4] = { + "v0 ", "t0 ", "t1 ", "t2 ", "t3 ", "t4 ", "t5 ", "t6 ", "t7 ", + "s0 ", "s1 ", "s2 ", "s3 ", "s4 ", "s5 ", "s6 ", "a0 ", "a1 ", + "a2 ", "a3 ", "a4 ", "a5 ", "t8 ", "t9 ", "t10", "t11", "ra ", + "pv ", "at ", "gp ", "sp ", "0" +}; + + +static instr * +display_stored_regs(instr * pro_pc, unsigned char * sp) +{ + instr * ret_pc = 0; + int reg; + unsigned long value; + + printk("Prologue [<%p>], Frame %p:\n", pro_pc, sp); + while (!BB_END(*pro_pc)) + if (STK_PUSH_MATCH(*pro_pc)) { + reg = (*pro_pc & MEM_REG) >> 21; + value = *(unsigned long *)(sp + (*pro_pc & MEM_OFF)); + if (reg == 26) + ret_pc = (instr *)value; + printk("\t\t%s / 0x%016lx\n", reg_name[reg], value); + } + return ret_pc; +} + +static instr * +seek_prologue(instr * pc) +{ + while (!STK_ALLOC_MATCH(*pc)) + --pc; + while (!BB_END(*(pc - 1))) + --pc; + return pc; +} + +static long +stack_increment(instr * prologue_pc) +{ + while (!STK_ALLOC_MATCH(*prologue_pc)) + ++prologue_pc; + + /* Count the bytes allocated. */ + if ((*prologue_pc & STK_ALLOC_1M) == STK_ALLOC_1M) + return -(((long)(*prologue_pc) << 48) >> 48); + else + return (*prologue_pc >> 13) & 0xff; +} + +void +stacktrace(void) +{ + instr * ret_pc; + instr * prologue = (instr *)stacktrace; + unsigned char *sp = (unsigned char *)current_stack_pointer; + + printk("\tstack trace:\n"); + do { + ret_pc = display_stored_regs(prologue, sp); + sp += stack_increment(prologue); + prologue = seek_prologue(ret_pc); + } while (IS_KERNEL_TEXT(ret_pc)); +} -- cgit v1.3.1