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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
Download Patch File Download Diff File Expand all files Collapse all files

134
arch/powerpc/lib/code-patching.c
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@@ -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));