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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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24a1bdc358
__ftrace_make_call assumed ABIv1 TOC stack offsets, so it broke on ABIv2. While we are here, we can simplify the instruction modification code. Since we always update one instruction there is no need to probe_kernel_write and flush_icache_range, just use patch_branch. Signed-off-by: Anton Blanchard <anton@samba.org>
594 lines
14 KiB
C
594 lines
14 KiB
C
/*
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* Code for replacing ftrace calls with jumps.
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*
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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*
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* Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box.
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*
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* Added function graph tracer code, taken from x86 that was written
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* by Frederic Weisbecker, and ported to PPC by Steven Rostedt.
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*
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*/
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#include <linux/spinlock.h>
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#include <linux/hardirq.h>
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#include <linux/uaccess.h>
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#include <linux/module.h>
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#include <linux/ftrace.h>
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#include <linux/percpu.h>
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#include <linux/init.h>
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#include <linux/list.h>
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#include <asm/cacheflush.h>
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#include <asm/code-patching.h>
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#include <asm/ftrace.h>
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#include <asm/syscall.h>
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#ifdef CONFIG_DYNAMIC_FTRACE
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static unsigned int
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ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
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{
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unsigned int op;
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addr = ppc_function_entry((void *)addr);
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/* if (link) set op to 'bl' else 'b' */
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op = create_branch((unsigned int *)ip, addr, link ? 1 : 0);
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return op;
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}
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static int
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ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new)
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{
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unsigned int replaced;
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/*
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* Note: Due to modules and __init, code can
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* disappear and change, we need to protect against faulting
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* as well as code changing. We do this by using the
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* probe_kernel_* functions.
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*
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* No real locking needed, this code is run through
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* kstop_machine, or before SMP starts.
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*/
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/* read the text we want to modify */
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if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* Make sure it is what we expect it to be */
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if (replaced != old)
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return -EINVAL;
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/* replace the text with the new text */
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if (patch_instruction((unsigned int *)ip, new))
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return -EPERM;
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return 0;
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}
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/*
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* Helper functions that are the same for both PPC64 and PPC32.
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*/
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static int test_24bit_addr(unsigned long ip, unsigned long addr)
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{
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addr = ppc_function_entry((void *)addr);
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/* use the create_branch to verify that this offset can be branched */
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return create_branch((unsigned int *)ip, addr, 0);
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}
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#ifdef CONFIG_MODULES
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static int is_bl_op(unsigned int op)
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{
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return (op & 0xfc000003) == 0x48000001;
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}
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static unsigned long find_bl_target(unsigned long ip, unsigned int op)
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{
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static int offset;
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offset = (op & 0x03fffffc);
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/* make it signed */
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if (offset & 0x02000000)
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offset |= 0xfe000000;
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return ip + (long)offset;
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}
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#ifdef CONFIG_PPC64
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static int
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__ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int op;
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unsigned long ptr;
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unsigned long ip = rec->ip;
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void *tramp;
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/* read where this goes */
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if (probe_kernel_read(&op, (void *)ip, sizeof(int)))
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return -EFAULT;
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/* Make sure that that this is still a 24bit jump */
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if (!is_bl_op(op)) {
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printk(KERN_ERR "Not expected bl: opcode is %x\n", op);
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return -EINVAL;
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}
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/* lets find where the pointer goes */
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tramp = (void *)find_bl_target(ip, op);
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pr_devel("ip:%lx jumps to %p", ip, tramp);
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if (!is_module_trampoline(tramp)) {
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printk(KERN_ERR "Not a trampoline\n");
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return -EINVAL;
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}
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if (module_trampoline_target(mod, tramp, &ptr)) {
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printk(KERN_ERR "Failed to get trampoline target\n");
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return -EFAULT;
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}
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pr_devel("trampoline target %lx", ptr);
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/* This should match what was called */
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if (ptr != ppc_function_entry((void *)addr)) {
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printk(KERN_ERR "addr %lx does not match expected %lx\n",
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ptr, ppc_function_entry((void *)addr));
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return -EINVAL;
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}
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/*
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* Our original call site looks like:
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*
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* bl <tramp>
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* ld r2,XX(r1)
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*
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* Milton Miller pointed out that we can not simply nop the branch.
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* If a task was preempted when calling a trace function, the nops
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* will remove the way to restore the TOC in r2 and the r2 TOC will
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* get corrupted.
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*
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* Use a b +8 to jump over the load.
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*/
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op = 0x48000008; /* b +8 */
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if (patch_instruction((unsigned int *)ip, op))
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return -EPERM;
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return 0;
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}
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#else /* !PPC64 */
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static int
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__ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int op;
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unsigned int jmp[4];
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unsigned long ip = rec->ip;
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unsigned long tramp;
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if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* Make sure that that this is still a 24bit jump */
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if (!is_bl_op(op)) {
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printk(KERN_ERR "Not expected bl: opcode is %x\n", op);
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return -EINVAL;
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}
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/* lets find where the pointer goes */
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tramp = find_bl_target(ip, op);
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/*
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* On PPC32 the trampoline looks like:
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* 0x3d, 0x80, 0x00, 0x00 lis r12,sym@ha
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* 0x39, 0x8c, 0x00, 0x00 addi r12,r12,sym@l
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* 0x7d, 0x89, 0x03, 0xa6 mtctr r12
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* 0x4e, 0x80, 0x04, 0x20 bctr
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*/
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pr_devel("ip:%lx jumps to %lx", ip, tramp);
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/* Find where the trampoline jumps to */
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if (probe_kernel_read(jmp, (void *)tramp, sizeof(jmp))) {
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printk(KERN_ERR "Failed to read %lx\n", tramp);
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return -EFAULT;
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}
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pr_devel(" %08x %08x ", jmp[0], jmp[1]);
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/* verify that this is what we expect it to be */
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if (((jmp[0] & 0xffff0000) != 0x3d800000) ||
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((jmp[1] & 0xffff0000) != 0x398c0000) ||
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(jmp[2] != 0x7d8903a6) ||
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(jmp[3] != 0x4e800420)) {
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printk(KERN_ERR "Not a trampoline\n");
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return -EINVAL;
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}
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tramp = (jmp[1] & 0xffff) |
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((jmp[0] & 0xffff) << 16);
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if (tramp & 0x8000)
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tramp -= 0x10000;
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pr_devel(" %lx ", tramp);
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if (tramp != addr) {
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printk(KERN_ERR
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"Trampoline location %08lx does not match addr\n",
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tramp);
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return -EINVAL;
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}
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op = PPC_INST_NOP;
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if (patch_instruction((unsigned int *)ip, op))
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return -EPERM;
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return 0;
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}
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#endif /* PPC64 */
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#endif /* CONFIG_MODULES */
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int ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned long ip = rec->ip;
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unsigned int old, new;
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/*
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* If the calling address is more that 24 bits away,
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* then we had to use a trampoline to make the call.
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* Otherwise just update the call site.
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*/
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if (test_24bit_addr(ip, addr)) {
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/* within range */
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old = ftrace_call_replace(ip, addr, 1);
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new = PPC_INST_NOP;
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return ftrace_modify_code(ip, old, new);
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}
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#ifdef CONFIG_MODULES
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/*
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* Out of range jumps are called from modules.
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* We should either already have a pointer to the module
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* or it has been passed in.
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*/
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if (!rec->arch.mod) {
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if (!mod) {
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printk(KERN_ERR "No module loaded addr=%lx\n",
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addr);
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return -EFAULT;
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}
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rec->arch.mod = mod;
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} else if (mod) {
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if (mod != rec->arch.mod) {
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printk(KERN_ERR
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"Record mod %p not equal to passed in mod %p\n",
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rec->arch.mod, mod);
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return -EINVAL;
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}
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/* nothing to do if mod == rec->arch.mod */
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} else
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mod = rec->arch.mod;
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return __ftrace_make_nop(mod, rec, addr);
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#else
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/* We should not get here without modules */
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return -EINVAL;
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#endif /* CONFIG_MODULES */
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}
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#ifdef CONFIG_MODULES
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#ifdef CONFIG_PPC64
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static int
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__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int op[2];
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void *ip = (void *)rec->ip;
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/* read where this goes */
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if (probe_kernel_read(op, ip, sizeof(op)))
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return -EFAULT;
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/*
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* We expect to see:
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*
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* b +8
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* ld r2,XX(r1)
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*
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* The load offset is different depending on the ABI. For simplicity
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* just mask it out when doing the compare.
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*/
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if ((op[0] != 0x48000008) || ((op[1] & 0xffff00000) != 0xe8410000)) {
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printk(KERN_ERR "Unexpected call sequence: %x %x\n",
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op[0], op[1]);
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return -EINVAL;
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}
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/* If we never set up a trampoline to ftrace_caller, then bail */
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if (!rec->arch.mod->arch.tramp) {
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printk(KERN_ERR "No ftrace trampoline\n");
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return -EINVAL;
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}
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/* Ensure branch is within 24 bits */
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if (create_branch(ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK)) {
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printk(KERN_ERR "Branch out of range");
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return -EINVAL;
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}
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if (patch_branch(ip, rec->arch.mod->arch.tramp, BRANCH_SET_LINK)) {
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printk(KERN_ERR "REL24 out of range!\n");
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return -EINVAL;
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}
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return 0;
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}
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#else
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static int
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__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int op;
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unsigned long ip = rec->ip;
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/* read where this goes */
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if (probe_kernel_read(&op, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* It should be pointing to a nop */
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if (op != PPC_INST_NOP) {
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printk(KERN_ERR "Expected NOP but have %x\n", op);
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return -EINVAL;
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}
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/* If we never set up a trampoline to ftrace_caller, then bail */
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if (!rec->arch.mod->arch.tramp) {
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printk(KERN_ERR "No ftrace trampoline\n");
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return -EINVAL;
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}
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/* create the branch to the trampoline */
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op = create_branch((unsigned int *)ip,
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rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
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if (!op) {
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printk(KERN_ERR "REL24 out of range!\n");
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return -EINVAL;
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}
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pr_devel("write to %lx\n", rec->ip);
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if (patch_instruction((unsigned int *)ip, op))
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return -EPERM;
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return 0;
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}
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#endif /* CONFIG_PPC64 */
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#endif /* CONFIG_MODULES */
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned long ip = rec->ip;
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unsigned int old, new;
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/*
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* If the calling address is more that 24 bits away,
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* then we had to use a trampoline to make the call.
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* Otherwise just update the call site.
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*/
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if (test_24bit_addr(ip, addr)) {
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/* within range */
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old = PPC_INST_NOP;
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new = ftrace_call_replace(ip, addr, 1);
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return ftrace_modify_code(ip, old, new);
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}
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#ifdef CONFIG_MODULES
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/*
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* Out of range jumps are called from modules.
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* Being that we are converting from nop, it had better
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* already have a module defined.
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*/
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if (!rec->arch.mod) {
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printk(KERN_ERR "No module loaded\n");
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return -EINVAL;
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}
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return __ftrace_make_call(rec, addr);
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#else
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/* We should not get here without modules */
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return -EINVAL;
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#endif /* CONFIG_MODULES */
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}
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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unsigned long ip = (unsigned long)(&ftrace_call);
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unsigned int old, new;
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int ret;
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old = *(unsigned int *)&ftrace_call;
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new = ftrace_call_replace(ip, (unsigned long)func, 1);
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ret = ftrace_modify_code(ip, old, new);
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return ret;
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}
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static int __ftrace_replace_code(struct dyn_ftrace *rec, int enable)
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{
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unsigned long ftrace_addr = (unsigned long)FTRACE_ADDR;
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int ret;
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ret = ftrace_update_record(rec, enable);
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switch (ret) {
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case FTRACE_UPDATE_IGNORE:
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return 0;
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case FTRACE_UPDATE_MAKE_CALL:
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return ftrace_make_call(rec, ftrace_addr);
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case FTRACE_UPDATE_MAKE_NOP:
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return ftrace_make_nop(NULL, rec, ftrace_addr);
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}
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return 0;
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}
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void ftrace_replace_code(int enable)
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{
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struct ftrace_rec_iter *iter;
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struct dyn_ftrace *rec;
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int ret;
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for (iter = ftrace_rec_iter_start(); iter;
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iter = ftrace_rec_iter_next(iter)) {
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rec = ftrace_rec_iter_record(iter);
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ret = __ftrace_replace_code(rec, enable);
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if (ret) {
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ftrace_bug(ret, rec->ip);
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return;
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}
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}
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}
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void arch_ftrace_update_code(int command)
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{
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if (command & FTRACE_UPDATE_CALLS)
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ftrace_replace_code(1);
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else if (command & FTRACE_DISABLE_CALLS)
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ftrace_replace_code(0);
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if (command & FTRACE_UPDATE_TRACE_FUNC)
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ftrace_update_ftrace_func(ftrace_trace_function);
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if (command & FTRACE_START_FUNC_RET)
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ftrace_enable_ftrace_graph_caller();
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else if (command & FTRACE_STOP_FUNC_RET)
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ftrace_disable_ftrace_graph_caller();
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}
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int __init ftrace_dyn_arch_init(void)
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{
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return 0;
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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#ifdef CONFIG_DYNAMIC_FTRACE
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extern void ftrace_graph_call(void);
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extern void ftrace_graph_stub(void);
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int ftrace_enable_ftrace_graph_caller(void)
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{
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unsigned long ip = (unsigned long)(&ftrace_graph_call);
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unsigned long addr = (unsigned long)(&ftrace_graph_caller);
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unsigned long stub = (unsigned long)(&ftrace_graph_stub);
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unsigned int old, new;
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old = ftrace_call_replace(ip, stub, 0);
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new = ftrace_call_replace(ip, addr, 0);
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return ftrace_modify_code(ip, old, new);
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}
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int ftrace_disable_ftrace_graph_caller(void)
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{
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unsigned long ip = (unsigned long)(&ftrace_graph_call);
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unsigned long addr = (unsigned long)(&ftrace_graph_caller);
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unsigned long stub = (unsigned long)(&ftrace_graph_stub);
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unsigned int old, new;
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old = ftrace_call_replace(ip, addr, 0);
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new = ftrace_call_replace(ip, stub, 0);
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return ftrace_modify_code(ip, old, new);
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#ifdef CONFIG_PPC64
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extern void mod_return_to_handler(void);
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#endif
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/*
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* Hook the return address and push it in the stack of return addrs
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* in current thread info.
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*/
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void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
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{
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unsigned long old;
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int faulted;
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struct ftrace_graph_ent trace;
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unsigned long return_hooker = (unsigned long)&return_to_handler;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return;
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#ifdef CONFIG_PPC64
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/* non core kernel code needs to save and restore the TOC */
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if (REGION_ID(self_addr) != KERNEL_REGION_ID)
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return_hooker = (unsigned long)&mod_return_to_handler;
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#endif
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return_hooker = ppc_function_entry((void *)return_hooker);
|
|
|
|
/*
|
|
* Protect against fault, even if it shouldn't
|
|
* happen. This tool is too much intrusive to
|
|
* ignore such a protection.
|
|
*/
|
|
asm volatile(
|
|
"1: " PPC_LL "%[old], 0(%[parent])\n"
|
|
"2: " PPC_STL "%[return_hooker], 0(%[parent])\n"
|
|
" li %[faulted], 0\n"
|
|
"3:\n"
|
|
|
|
".section .fixup, \"ax\"\n"
|
|
"4: li %[faulted], 1\n"
|
|
" b 3b\n"
|
|
".previous\n"
|
|
|
|
".section __ex_table,\"a\"\n"
|
|
PPC_LONG_ALIGN "\n"
|
|
PPC_LONG "1b,4b\n"
|
|
PPC_LONG "2b,4b\n"
|
|
".previous"
|
|
|
|
: [old] "=&r" (old), [faulted] "=r" (faulted)
|
|
: [parent] "r" (parent), [return_hooker] "r" (return_hooker)
|
|
: "memory"
|
|
);
|
|
|
|
if (unlikely(faulted)) {
|
|
ftrace_graph_stop();
|
|
WARN_ON(1);
|
|
return;
|
|
}
|
|
|
|
trace.func = self_addr;
|
|
trace.depth = current->curr_ret_stack + 1;
|
|
|
|
/* Only trace if the calling function expects to */
|
|
if (!ftrace_graph_entry(&trace)) {
|
|
*parent = old;
|
|
return;
|
|
}
|
|
|
|
if (ftrace_push_return_trace(old, self_addr, &trace.depth, 0) == -EBUSY)
|
|
*parent = old;
|
|
}
|
|
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
|
|
|
|
#if defined(CONFIG_FTRACE_SYSCALLS) && defined(CONFIG_PPC64)
|
|
unsigned long __init arch_syscall_addr(int nr)
|
|
{
|
|
return sys_call_table[nr*2];
|
|
}
|
|
#endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_PPC64 */
|