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powerpc: Change calling convention for create_branch() et. al.

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create_branch(), create_cond_branch() and translate_branch() return the
instruction that they create, or return 0 to signal an error. Separate
these concerns in preparation for an instruction type that is not just
an unsigned int.  Fill the created instruction to a pointer passed as
the first parameter to the function and use a non-zero return value to
signify an error.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-6-jniethe5@gmail.com
This commit is contained in:
Jordan Niethe 2020-05-06 13:40:25 +10:00 committed by Michael Ellerman
parent 5a7fdcab54
commit 7c95d8893f
6 changed files with 119 additions and 84 deletions
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12
arch/powerpc/include/asm/code-patching.h
View File

@ -22,10 +22,10 @@
#define BRANCH_ABSOLUTE 0x2
bool is_offset_in_branch_range(long offset);
unsigned int create_branch(const unsigned int *addr,
unsigned long target, int flags);
unsigned int create_cond_branch(const unsigned int *addr,
unsigned long target, int flags);
int create_branch(unsigned int *instr, const unsigned int *addr,
unsigned long target, int flags);
int create_cond_branch(unsigned int *instr, const unsigned int *addr,
unsigned long target, int flags);
int patch_branch(unsigned int *addr, unsigned long target, int flags);
int patch_instruction(unsigned int *addr, unsigned int instr);
int raw_patch_instruction(unsigned int *addr, unsigned int instr);
@ -60,8 +60,8 @@ int instr_is_relative_branch(unsigned int instr);
int instr_is_relative_link_branch(unsigned int instr);
int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
unsigned long branch_target(const unsigned int *instr);
unsigned int translate_branch(const unsigned int *dest,
const unsigned int *src);
int translate_branch(unsigned int *instr, const unsigned int *dest,
const unsigned int *src);
extern bool is_conditional_branch(unsigned int instr);
#ifdef CONFIG_PPC_BOOK3E_64
void __patch_exception(int exc, unsigned long addr);

24
arch/powerpc/kernel/optprobes.c
View File

@ -251,15 +251,17 @@ int arch_prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
goto error;
}
branch_op_callback = create_branch((unsigned int *)buff + TMPL_CALL_HDLR_IDX,
(unsigned long)op_callback_addr,
BRANCH_SET_LINK);
rc = create_branch(&branch_op_callback,
(unsigned int *)buff + TMPL_CALL_HDLR_IDX,
(unsigned long)op_callback_addr,
BRANCH_SET_LINK);
branch_emulate_step = create_branch((unsigned int *)buff + TMPL_EMULATE_IDX,
(unsigned long)emulate_step_addr,
BRANCH_SET_LINK);
rc |= create_branch(&branch_emulate_step,
(unsigned int *)buff + TMPL_EMULATE_IDX,
(unsigned long)emulate_step_addr,
BRANCH_SET_LINK);
if (!branch_op_callback || !branch_emulate_step)
if (rc)
goto error;
patch_instruction(buff + TMPL_CALL_HDLR_IDX, branch_op_callback);
@ -305,6 +307,7 @@ int arch_check_optimized_kprobe(struct optimized_kprobe *op)
void arch_optimize_kprobes(struct list_head *oplist)
{
unsigned int instr;
struct optimized_kprobe *op;
struct optimized_kprobe *tmp;
@ -315,9 +318,10 @@ void arch_optimize_kprobes(struct list_head *oplist)
*/
memcpy(op->optinsn.copied_insn, op->kp.addr,
RELATIVEJUMP_SIZE);
patch_instruction(op->kp.addr,
create_branch((unsigned int *)op->kp.addr,
(unsigned long)op->optinsn.insn, 0));
create_branch(&instr,
(unsigned int *)op->kp.addr,
(unsigned long)op->optinsn.insn, 0);
patch_instruction(op->kp.addr, instr);
list_del_init(&op->list);
}
}

4
arch/powerpc/kernel/setup_32.c
View File

@ -75,7 +75,7 @@ EXPORT_SYMBOL(DMA_MODE_WRITE);
notrace void __init machine_init(u64 dt_ptr)
{
unsigned int *addr = (unsigned int *)patch_site_addr(&patch__memset_nocache);
unsigned long insn;
unsigned int insn;
/* Configure static keys first, now that we're relocated. */
setup_feature_keys();
@ -87,7 +87,7 @@ notrace void __init machine_init(u64 dt_ptr)
patch_instruction_site(&patch__memcpy_nocache, PPC_INST_NOP);
insn = create_cond_branch(addr, branch_target(addr), 0x820000);
create_cond_branch(&insn, addr, branch_target(addr), 0x820000);
patch_instruction(addr, insn); /* replace b by bne cr0 */
/* Do some early initialization based on the flat device tree */

24
arch/powerpc/kernel/trace/ftrace.c
View File

@ -48,7 +48,7 @@ ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
addr = ppc_function_entry((void *)addr);
/* if (link) set op to 'bl' else 'b' */
op = create_branch((unsigned int *)ip, addr, link ? 1 : 0);
create_branch(&op, (unsigned int *)ip, addr, link ? 1 : 0);
return op;
}
@ -89,10 +89,11 @@ ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new)
*/
static int test_24bit_addr(unsigned long ip, unsigned long addr)
{
unsigned int op;
addr = ppc_function_entry((void *)addr);
/* use the create_branch to verify that this offset can be branched */
return create_branch((unsigned int *)ip, addr, 0);
return create_branch(&op, (unsigned int *)ip, addr, 0) == 0;
}
static int is_bl_op(unsigned int op)
@ -287,6 +288,7 @@ __ftrace_make_nop(struct module *mod,
static unsigned long find_ftrace_tramp(unsigned long ip)
{
int i;
unsigned int instr;
/*
* We have the compiler generated long_branch tramps at the end
@ -295,7 +297,8 @@ static unsigned long find_ftrace_tramp(unsigned long ip)
for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
if (!ftrace_tramps[i])
continue;
else if (create_branch((void *)ip, ftrace_tramps[i], 0))
else if (create_branch(&instr, (void *)ip,
ftrace_tramps[i], 0) == 0)
return ftrace_tramps[i];
return 0;
@ -324,6 +327,7 @@ static int setup_mcount_compiler_tramp(unsigned long tramp)
{
int i, op;
unsigned long ptr;
unsigned int instr;
static unsigned long ftrace_plt_tramps[NUM_FTRACE_TRAMPS];
/* Is this a known long jump tramp? */
@ -366,7 +370,7 @@ static int setup_mcount_compiler_tramp(unsigned long tramp)
#else
ptr = ppc_global_function_entry((void *)ftrace_caller);
#endif
if (!create_branch((void *)tramp, ptr, 0)) {
if (create_branch(&instr, (void *)tramp, ptr, 0)) {
pr_debug("%ps is not reachable from existing mcount tramp\n",
(void *)ptr);
return -1;
@ -511,6 +515,7 @@ static int
__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned int op[2];
unsigned int instr;
void *ip = (void *)rec->ip;
unsigned long entry, ptr, tramp;
struct module *mod = rec->arch.mod;
@ -557,7 +562,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
}
/* Ensure branch is within 24 bits */
if (!create_branch(ip, tramp, BRANCH_SET_LINK)) {
if (create_branch(&instr, ip, tramp, BRANCH_SET_LINK)) {
pr_err("Branch out of range\n");
return -EINVAL;
}
@ -574,6 +579,7 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
static int
__ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
int err;
unsigned int op;
unsigned long ip = rec->ip;
@ -594,9 +600,9 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
}
/* create the branch to the trampoline */
op = create_branch((unsigned int *)ip,
rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
if (!op) {
err = create_branch(&op, (unsigned int *)ip,
rec->arch.mod->arch.tramp, BRANCH_SET_LINK);
if (err) {
pr_err("REL24 out of range!\n");
return -EINVAL;
}
@ -776,7 +782,7 @@ __ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
}
/* Ensure branch is within 24 bits */
if (!create_branch((unsigned int *)ip, tramp, BRANCH_SET_LINK)) {
if (create_branch(&op, (unsigned int *)ip, tramp, BRANCH_SET_LINK)) {
pr_err("Branch out of range\n");
return -EINVAL;
}

134
arch/powerpc/lib/code-patching.c
View File

@ -196,7 +196,10 @@ NOKPROBE_SYMBOL(patch_instruction);
int patch_branch(unsigned int *addr, unsigned long target, int flags)
{
return patch_instruction(addr, create_branch(addr, target, flags));
unsigned int instr;
create_branch(&instr, addr, target, flags);
return patch_instruction(addr, instr);
}
bool is_offset_in_branch_range(long offset)
@ -243,30 +246,30 @@ bool is_conditional_branch(unsigned int instr)
}
NOKPROBE_SYMBOL(is_conditional_branch);
unsigned int create_branch(const unsigned int *addr,
unsigned long target, int flags)
int create_branch(unsigned int *instr,
const unsigned int *addr,
unsigned long target, int flags)
{
unsigned int instruction;
long offset;
*instr = 0;
offset = target;
if (! (flags & BRANCH_ABSOLUTE))
offset = offset - (unsigned long)addr;
/* Check we can represent the target in the instruction format */
if (!is_offset_in_branch_range(offset))
return 0;
return 1;
/* Mask out the flags and target, so they don't step on each other. */
instruction = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
*instr = 0x48000000 | (flags & 0x3) | (offset & 0x03FFFFFC);
return instruction;
return 0;
}
unsigned int create_cond_branch(const unsigned int *addr,
unsigned long target, int flags)
int create_cond_branch(unsigned int *instr, const unsigned int *addr,
unsigned long target, int flags)
{
unsigned int instruction;
long offset;
offset = target;
@ -275,12 +278,12 @@ unsigned int create_cond_branch(const unsigned int *addr,
/* Check we can represent the target in the instruction format */
if (offset < -0x8000 || offset > 0x7FFF || offset & 0x3)
return 0;
return 1;
/* Mask out the flags and target, so they don't step on each other. */
instruction = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
*instr = 0x40000000 | (flags & 0x3FF0003) | (offset & 0xFFFC);
return instruction;
return 0;
}
static unsigned int branch_opcode(unsigned int instr)
@ -361,18 +364,19 @@ int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr)
return 0;
}
unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
int translate_branch(unsigned int *instr, const unsigned int *dest,
const unsigned int *src)
{
unsigned long target;
target = branch_target(src);
if (instr_is_branch_iform(*src))
return create_branch(dest, target, *src);
return create_branch(instr, dest, target, *src);
else if (instr_is_branch_bform(*src))
return create_cond_branch(dest, target, *src);
return create_cond_branch(instr, dest, target, *src);
return 0;
return 1;
}
#ifdef CONFIG_PPC_BOOK3E_64
@ -403,6 +407,7 @@ static void __init test_trampoline(void)
static void __init test_branch_iform(void)
{
int err;
unsigned int instr;
unsigned long addr;
@ -443,35 +448,35 @@ static void __init test_branch_iform(void)
check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
/* Branch to self, with link */
instr = create_branch(&instr, addr, BRANCH_SET_LINK);
err = create_branch(&instr, &instr, addr, BRANCH_SET_LINK);
check(instr_is_branch_to_addr(&instr, addr));
/* Branch to self - 0x100, with link */
instr = create_branch(&instr, addr - 0x100, BRANCH_SET_LINK);
err = create_branch(&instr, &instr, addr - 0x100, BRANCH_SET_LINK);
check(instr_is_branch_to_addr(&instr, addr - 0x100));
/* Branch to self + 0x100, no link */
instr = create_branch(&instr, addr + 0x100, 0);
err = create_branch(&instr, &instr, addr + 0x100, 0);
check(instr_is_branch_to_addr(&instr, addr + 0x100));
/* Maximum relative negative offset, - 32 MB */
instr = create_branch(&instr, addr - 0x2000000, BRANCH_SET_LINK);
err = create_branch(&instr, &instr, addr - 0x2000000, BRANCH_SET_LINK);
check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
/* Out of range relative negative offset, - 32 MB + 4*/
instr = create_branch(&instr, addr - 0x2000004, BRANCH_SET_LINK);
check(instr == 0);
err = create_branch(&instr, &instr, addr - 0x2000004, BRANCH_SET_LINK);
check(err);
/* Out of range relative positive offset, + 32 MB */
instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
check(instr == 0);
err = create_branch(&instr, &instr, addr + 0x2000000, BRANCH_SET_LINK);
check(err);
/* Unaligned target */
instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
check(instr == 0);
err = create_branch(&instr, &instr, addr + 3, BRANCH_SET_LINK);
check(err);
/* Check flags are masked correctly */
instr = create_branch(&instr, addr, 0xFFFFFFFC);
err = create_branch(&instr, &instr, addr, 0xFFFFFFFC);
check(instr_is_branch_to_addr(&instr, addr));
check(instr == 0x48000000);
}
@ -480,16 +485,19 @@ static void __init test_create_function_call(void)
{
unsigned int *iptr;
unsigned long dest;
unsigned int instr;
/* Check we can create a function call */
iptr = (unsigned int *)ppc_function_entry(test_trampoline);
dest = ppc_function_entry(test_create_function_call);
patch_instruction(iptr, create_branch(iptr, dest, BRANCH_SET_LINK));
create_branch(&instr, iptr, dest, BRANCH_SET_LINK);
patch_instruction(iptr, instr);
check(instr_is_branch_to_addr(iptr, dest));
}
static void __init test_branch_bform(void)
{
int err;
unsigned long addr;
unsigned int *iptr, instr, flags;
@ -525,35 +533,35 @@ static void __init test_branch_bform(void)
flags = 0x3ff000 | BRANCH_SET_LINK;
/* Branch to self */
instr = create_cond_branch(iptr, addr, flags);
err = create_cond_branch(&instr, iptr, addr, flags);
check(instr_is_branch_to_addr(&instr, addr));
/* Branch to self - 0x100 */
instr = create_cond_branch(iptr, addr - 0x100, flags);
err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
check(instr_is_branch_to_addr(&instr, addr - 0x100));
/* Branch to self + 0x100 */
instr = create_cond_branch(iptr, addr + 0x100, flags);
err = create_cond_branch(&instr, iptr, addr + 0x100, flags);
check(instr_is_branch_to_addr(&instr, addr + 0x100));
/* Maximum relative negative offset, - 32 KB */
instr = create_cond_branch(iptr, addr - 0x8000, flags);
err = create_cond_branch(&instr, iptr, addr - 0x8000, flags);
check(instr_is_branch_to_addr(&instr, addr - 0x8000));
/* Out of range relative negative offset, - 32 KB + 4*/
instr = create_cond_branch(iptr, addr - 0x8004, flags);
check(instr == 0);
err = create_cond_branch(&instr, iptr, addr - 0x8004, flags);
check(err);
/* Out of range relative positive offset, + 32 KB */
instr = create_cond_branch(iptr, addr + 0x8000, flags);
check(instr == 0);
err = create_cond_branch(&instr, iptr, addr + 0x8000, flags);
check(err);
/* Unaligned target */
instr = create_cond_branch(iptr, addr + 3, flags);
check(instr == 0);
err = create_cond_branch(&instr, iptr, addr + 3, flags);
check(err);
/* Check flags are masked correctly */
instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
err = create_cond_branch(&instr, iptr, addr, 0xFFFFFFFC);
check(instr_is_branch_to_addr(&instr, addr));
check(instr == 0x43FF0000);
}
@ -562,6 +570,7 @@ static void __init test_translate_branch(void)
{
unsigned long addr;
unsigned int *p, *q;
unsigned int instr;
void *buf;
buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
@ -575,7 +584,8 @@ static void __init test_translate_branch(void)
patch_branch(p, addr, 0);
check(instr_is_branch_to_addr(p, addr));
q = p + 1;
patch_instruction(q, translate_branch(q, p));
translate_branch(&instr, q, p);
patch_instruction(q, instr);
check(instr_is_branch_to_addr(q, addr));
/* Maximum negative case, move b . to addr + 32 MB */
@ -583,7 +593,8 @@ static void __init test_translate_branch(void)
addr = (unsigned long)p;
patch_branch(p, addr, 0);
q = buf + 0x2000000;
patch_instruction(q, translate_branch(q, p));
translate_branch(&instr, q, p);
patch_instruction(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
check(*q == 0x4a000000);
@ -593,7 +604,8 @@ static void __init test_translate_branch(void)
addr = (unsigned long)p;
patch_branch(p, addr, 0);
q = buf + 4;
patch_instruction(q, translate_branch(q, p));
translate_branch(&instr, q, p);
patch_instruction(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
check(*q == 0x49fffffc);
@ -603,7 +615,8 @@ static void __init test_translate_branch(void)
addr = 0x1000000 + (unsigned long)buf;
patch_branch(p, addr, BRANCH_SET_LINK);
q = buf + 0x1400000;
patch_instruction(q, translate_branch(q, p));
translate_branch(&instr, q, p);
patch_instruction(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
@ -612,7 +625,8 @@ static void __init test_translate_branch(void)
addr = 0x2000000 + (unsigned long)buf;
patch_branch(p, addr, 0);
q = buf + 4;
patch_instruction(q, translate_branch(q, p));
translate_branch(&instr, q, p);
patch_instruction(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
@ -622,18 +636,22 @@ static void __init test_translate_branch(void)
/* Simple case, branch to self moved a little */
p = buf;
addr = (unsigned long)p;
patch_instruction(p, create_cond_branch(p, addr, 0));
create_cond_branch(&instr, p, addr, 0);
patch_instruction(p, instr);
check(instr_is_branch_to_addr(p, addr));
q = p + 1;
patch_instruction(q, translate_branch(q, p));
translate_branch(&instr, q, p);
patch_instruction(q, instr);
check(instr_is_branch_to_addr(q, addr));
/* Maximum negative case, move b . to addr + 32 KB */
p = buf;
addr = (unsigned long)p;
patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
patch_instruction(p, instr);
q = buf + 0x8000;
patch_instruction(q, translate_branch(q, p));
translate_branch(&instr, q, p);
patch_instruction(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
check(*q == 0x43ff8000);
@ -641,9 +659,11 @@ static void __init test_translate_branch(void)
/* Maximum positive case, move x to x - 32 KB + 4 */
p = buf + 0x8000;
addr = (unsigned long)p;
patch_instruction(p, create_cond_branch(p, addr, 0xFFFFFFFC));
create_cond_branch(&instr, p, addr, 0xFFFFFFFC);
patch_instruction(p, instr);
q = buf + 4;
patch_instruction(q, translate_branch(q, p));
translate_branch(&instr, q, p);
patch_instruction(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
check(*q == 0x43ff7ffc);
@ -651,18 +671,22 @@ static void __init test_translate_branch(void)
/* Jump to x + 12 KB moved to x + 20 KB */
p = buf;
addr = 0x3000 + (unsigned long)buf;
patch_instruction(p, create_cond_branch(p, addr, BRANCH_SET_LINK));
create_cond_branch(&instr, p, addr, BRANCH_SET_LINK);
patch_instruction(p, instr);
q = buf + 0x5000;
patch_instruction(q, translate_branch(q, p));
translate_branch(&instr, q, p);
patch_instruction(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));
/* Jump to x + 8 KB moved to x - 8 KB + 4 */
p = buf + 0x2000;
addr = 0x4000 + (unsigned long)buf;
patch_instruction(p, create_cond_branch(p, addr, 0));
create_cond_branch(&instr, p, addr, 0);
patch_instruction(p, instr);
q = buf + 4;
patch_instruction(q, translate_branch(q, p));
translate_branch(&instr, q, p);
patch_instruction(q, instr);
check(instr_is_branch_to_addr(p, addr));
check(instr_is_branch_to_addr(q, addr));

5
arch/powerpc/lib/feature-fixups.c
View File

@ -44,6 +44,7 @@ static unsigned int *calc_addr(struct fixup_entry *fcur, long offset)
static int patch_alt_instruction(unsigned int *src, unsigned int *dest,
unsigned int *alt_start, unsigned int *alt_end)
{
int err;
unsigned int instr;
instr = *src;
@ -53,8 +54,8 @@ static int patch_alt_instruction(unsigned int *src, unsigned int *dest,
/* Branch within the section doesn't need translating */
if (target < alt_start || target > alt_end) {
instr = translate_branch(dest, src);
if (!instr)
err = translate_branch(&instr, dest, src);
if (err)
return 1;
}
}