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powerpc/ftrace: Make __ftrace_make_{nop/call}() common to PPC32 and P…
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…PC64

Since c93d4f6 ("powerpc/ftrace: Add module_trampoline_target()
for PPC32"), __ftrace_make_nop() for PPC32 is very similar to the
one for PPC64.

Same for __ftrace_make_call().

Make them common.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/96f53c237316dab4b1b8c682685266faa92da816.1652074503.git.christophe.leroy@csgroup.eu
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Christophe Leroy authored and Michael Ellerman committed May 19, 2022
1 parent 5b89492 commit 23b44fc
Showing 1 changed file with 8 additions and 100 deletions.
108 changes: 8 additions & 100 deletions arch/powerpc/kernel/trace/ftrace.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -114,7 +114,6 @@ static unsigned long find_bl_target(unsigned long ip, ppc_inst_t op)
}

#ifdef CONFIG_MODULES
#ifdef CONFIG_PPC64
static int
__ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
Expand Down Expand Up @@ -154,10 +153,11 @@ __ftrace_make_nop(struct module *mod,
return -EINVAL;
}

#ifdef CONFIG_MPROFILE_KERNEL
/* When using -mkernel_profile there is no load to jump over */
/* When using -mprofile-kernel or PPC32 there is no load to jump over */
pop = ppc_inst(PPC_RAW_NOP());

#ifdef CONFIG_PPC64
#ifdef CONFIG_MPROFILE_KERNEL
if (copy_inst_from_kernel_nofault(&op, (void *)(ip - 4))) {
pr_err("Fetching instruction at %lx failed.\n", ip - 4);
return -EFAULT;
Expand Down Expand Up @@ -201,6 +201,7 @@ __ftrace_make_nop(struct module *mod,
return -EINVAL;
}
#endif /* CONFIG_MPROFILE_KERNEL */
#endif /* PPC64 */

if (patch_instruction((u32 *)ip, pop)) {
pr_err("Patching NOP failed.\n");
Expand All @@ -209,48 +210,6 @@ __ftrace_make_nop(struct module *mod,

return 0;
}

#else /* !PPC64 */
static int
__ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
ppc_inst_t op;
unsigned long ip = rec->ip;
unsigned long tramp, ptr;

if (copy_from_kernel_nofault(&op, (void *)ip, MCOUNT_INSN_SIZE))
return -EFAULT;

/* Make sure that that this is still a 24bit jump */
if (!is_bl_op(op)) {
pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
return -EINVAL;
}

/* lets find where the pointer goes */
tramp = find_bl_target(ip, op);

/* Find where the trampoline jumps to */
if (module_trampoline_target(mod, tramp, &ptr)) {
pr_err("Failed to get trampoline target\n");
return -EFAULT;
}

if (ptr != addr) {
pr_err("Trampoline location %08lx does not match addr\n",
tramp);
return -EINVAL;
}

op = ppc_inst(PPC_RAW_NOP());

if (patch_instruction((u32 *)ip, op))
return -EPERM;

return 0;
}
#endif /* PPC64 */
#endif /* CONFIG_MODULES */

static unsigned long find_ftrace_tramp(unsigned long ip)
Expand Down Expand Up @@ -437,13 +396,12 @@ int ftrace_make_nop(struct module *mod,
}

#ifdef CONFIG_MODULES
#ifdef CONFIG_PPC64
/*
* Examine the existing instructions for __ftrace_make_call.
* They should effectively be a NOP, and follow formal constraints,
* depending on the ABI. Return false if they don't.
*/
#ifndef CONFIG_MPROFILE_KERNEL
#ifdef CONFIG_PPC64_ELF_ABI_V1
static int
expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
{
Expand All @@ -465,7 +423,7 @@ expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
static int
expected_nop_sequence(void *ip, ppc_inst_t op0, ppc_inst_t op1)
{
/* look for patched "NOP" on ppc64 with -mprofile-kernel */
/* look for patched "NOP" on ppc64 with -mprofile-kernel or ppc32 */
if (!ppc_inst_equal(op0, ppc_inst(PPC_RAW_NOP())))
return 0;
return 1;
Expand All @@ -484,8 +442,10 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
if (copy_inst_from_kernel_nofault(op, ip))
return -EFAULT;

#ifdef CONFIG_PPC64_ELF_ABI_V1
if (copy_inst_from_kernel_nofault(op + 1, ip + 4))
return -EFAULT;
#endif

if (!expected_nop_sequence(ip, op[0], op[1])) {
pr_err("Unexpected call sequence at %p: %s %s\n",
Expand Down Expand Up @@ -531,58 +491,6 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)

return 0;
}

#else /* !CONFIG_PPC64: */
static int
__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
int err;
ppc_inst_t op;
u32 *ip = (u32 *)rec->ip;
struct module *mod = rec->arch.mod;
unsigned long tramp;

/* read where this goes */
if (copy_inst_from_kernel_nofault(&op, ip))
return -EFAULT;

/* It should be pointing to a nop */
if (!ppc_inst_equal(op, ppc_inst(PPC_RAW_NOP()))) {
pr_err("Expected NOP but have %s\n", ppc_inst_as_str(op));
return -EINVAL;
}

/* If we never set up a trampoline to ftrace_caller, then bail */
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
if (!mod->arch.tramp || !mod->arch.tramp_regs) {
#else
if (!mod->arch.tramp) {
#endif
pr_err("No ftrace trampoline\n");
return -EINVAL;
}

#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
if (rec->flags & FTRACE_FL_REGS)
tramp = mod->arch.tramp_regs;
else
#endif
tramp = mod->arch.tramp;
/* create the branch to the trampoline */
err = create_branch(&op, ip, tramp, BRANCH_SET_LINK);
if (err) {
pr_err("REL24 out of range!\n");
return -EINVAL;
}

pr_devel("write to %lx\n", rec->ip);

if (patch_instruction(ip, op))
return -EPERM;

return 0;
}
#endif /* CONFIG_PPC64 */
#endif /* CONFIG_MODULES */

static int __ftrace_make_call_kernel(struct dyn_ftrace *rec, unsigned long addr)
Expand Down

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