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    SubjectRe: [PATCH v2 07/12] powerpc/lib/code-patching: Don't use struct 'ppc_inst' for runnable code in tests.
    On Thu, May 20, 2021 at 11:50 PM Christophe Leroy
    <christophe.leroy@csgroup.eu> wrote:
    >
    > 'struct ppc_inst' is meant to represent an instruction internally, it
    > is not meant to dereference code in memory.
    >
    > For testing code patching, use patch_instruction() to properly
    > write into memory the code to be tested.
    >
    > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
    > ---
    > arch/powerpc/lib/code-patching.c | 95 ++++++++++++++++++--------------
    > 1 file changed, 53 insertions(+), 42 deletions(-)
    >
    > diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
    > index 82f2c1edb498..508e9511ca96 100644
    > --- a/arch/powerpc/lib/code-patching.c
    > +++ b/arch/powerpc/lib/code-patching.c
    > @@ -422,9 +422,9 @@ static void __init test_branch_iform(void)
    > {
    > int err;
    > struct ppc_inst instr;
    > - unsigned long addr;
    > -
    > - addr = (unsigned long)&instr;
    > + unsigned int tmp[2];
    > + struct ppc_inst *iptr = (struct ppc_inst *)tmp;
    > + unsigned long addr = (unsigned long)tmp;
    >
    > /* The simplest case, branch to self, no flags */
    > check(instr_is_branch_iform(ppc_inst(0x48000000)));
    > @@ -445,52 +445,57 @@ static void __init test_branch_iform(void)
    > check(!instr_is_branch_iform(ppc_inst(0x7bfffffd)));
    >
    > /* Absolute branch to 0x100 */
    > - instr = ppc_inst(0x48000103);
    > - check(instr_is_branch_to_addr(&instr, 0x100));
    > + patch_instruction(iptr, ppc_inst(0x48000103));
    > + check(instr_is_branch_to_addr(iptr, 0x100));
    > /* Absolute branch to 0x420fc */
    > - instr = ppc_inst(0x480420ff);
    > - check(instr_is_branch_to_addr(&instr, 0x420fc));
    > + patch_instruction(iptr, ppc_inst(0x480420ff));
    > + check(instr_is_branch_to_addr(iptr, 0x420fc));
    > /* Maximum positive relative branch, + 20MB - 4B */
    > - instr = ppc_inst(0x49fffffc);
    > - check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
    > + patch_instruction(iptr, ppc_inst(0x49fffffc));
    > + check(instr_is_branch_to_addr(iptr, addr + 0x1FFFFFC));
    > /* Smallest negative relative branch, - 4B */
    > - instr = ppc_inst(0x4bfffffc);
    > - check(instr_is_branch_to_addr(&instr, addr - 4));
    > + patch_instruction(iptr, ppc_inst(0x4bfffffc));
    > + check(instr_is_branch_to_addr(iptr, addr - 4));
    > /* Largest negative relative branch, - 32 MB */
    > - instr = ppc_inst(0x4a000000);
    > - check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
    > + patch_instruction(iptr, ppc_inst(0x4a000000));
    > + check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
    >
    > /* Branch to self, with link */
    > - err = create_branch(&instr, &instr, addr, BRANCH_SET_LINK);
    > - check(instr_is_branch_to_addr(&instr, addr));
    > + err = create_branch(&instr, iptr, addr, BRANCH_SET_LINK);
    > + patch_instruction(iptr, instr);
    > + check(instr_is_branch_to_addr(iptr, addr));
    >
    > /* Branch to self - 0x100, with link */
    > - err = create_branch(&instr, &instr, addr - 0x100, BRANCH_SET_LINK);
    > - check(instr_is_branch_to_addr(&instr, addr - 0x100));
    > + err = create_branch(&instr, iptr, addr - 0x100, BRANCH_SET_LINK);
    > + patch_instruction(iptr, instr);
    > + check(instr_is_branch_to_addr(iptr, addr - 0x100));
    >
    > /* Branch to self + 0x100, no link */
    > - err = create_branch(&instr, &instr, addr + 0x100, 0);
    > - check(instr_is_branch_to_addr(&instr, addr + 0x100));
    > + err = create_branch(&instr, iptr, addr + 0x100, 0);
    > + patch_instruction(iptr, instr);
    > + check(instr_is_branch_to_addr(iptr, addr + 0x100));
    >
    > /* Maximum relative negative offset, - 32 MB */
    > - err = create_branch(&instr, &instr, addr - 0x2000000, BRANCH_SET_LINK);
    > - check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
    > + err = create_branch(&instr, iptr, addr - 0x2000000, BRANCH_SET_LINK);
    > + patch_instruction(iptr, instr);
    > + check(instr_is_branch_to_addr(iptr, addr - 0x2000000));
    >
    > /* Out of range relative negative offset, - 32 MB + 4*/
    > - err = create_branch(&instr, &instr, addr - 0x2000004, BRANCH_SET_LINK);
    > + err = create_branch(&instr, iptr, addr - 0x2000004, BRANCH_SET_LINK);
    > check(err);
    >
    > /* Out of range relative positive offset, + 32 MB */
    > - err = create_branch(&instr, &instr, addr + 0x2000000, BRANCH_SET_LINK);
    > + err = create_branch(&instr, iptr, addr + 0x2000000, BRANCH_SET_LINK);
    > check(err);
    >
    > /* Unaligned target */
    > - err = create_branch(&instr, &instr, addr + 3, BRANCH_SET_LINK);
    > + err = create_branch(&instr, iptr, addr + 3, BRANCH_SET_LINK);
    > check(err);
    >
    > /* Check flags are masked correctly */
    > - err = create_branch(&instr, &instr, addr, 0xFFFFFFFC);
    > - check(instr_is_branch_to_addr(&instr, addr));
    > + err = create_branch(&instr, iptr, addr, 0xFFFFFFFC);
    > + patch_instruction(iptr, instr);
    > + check(instr_is_branch_to_addr(iptr, addr));
    > check(ppc_inst_equal(instr, ppc_inst(0x48000000)));
    > }
    >
    > @@ -513,9 +518,10 @@ static void __init test_branch_bform(void)
    > int err;
    > unsigned long addr;
    > struct ppc_inst *iptr, instr;
    > + unsigned int tmp[2];
    > unsigned int flags;
    >
    > - iptr = &instr;
    > + iptr = (struct ppc_inst *)tmp;
    > addr = (unsigned long)iptr;
    >
    > /* The simplest case, branch to self, no flags */
    > @@ -528,39 +534,43 @@ static void __init test_branch_bform(void)
    > check(!instr_is_branch_bform(ppc_inst(0x7bffffff)));
    >
    > /* Absolute conditional branch to 0x100 */
    > - instr = ppc_inst(0x43ff0103);
    > - check(instr_is_branch_to_addr(&instr, 0x100));
    > + patch_instruction(iptr, ppc_inst(0x43ff0103));
    > + check(instr_is_branch_to_addr(iptr, 0x100));
    > /* Absolute conditional branch to 0x20fc */
    > - instr = ppc_inst(0x43ff20ff);
    > - check(instr_is_branch_to_addr(&instr, 0x20fc));
    > + patch_instruction(iptr, ppc_inst(0x43ff20ff));
    > + check(instr_is_branch_to_addr(iptr, 0x20fc));
    > /* Maximum positive relative conditional branch, + 32 KB - 4B */
    > - instr = ppc_inst(0x43ff7ffc);
    > - check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
    > + patch_instruction(iptr, ppc_inst(0x43ff7ffc));
    > + check(instr_is_branch_to_addr(iptr, addr + 0x7FFC));
    > /* Smallest negative relative conditional branch, - 4B */
    > - instr = ppc_inst(0x43fffffc);
    > - check(instr_is_branch_to_addr(&instr, addr - 4));
    > + patch_instruction(iptr, ppc_inst(0x43fffffc));
    > + check(instr_is_branch_to_addr(iptr, addr - 4));
    > /* Largest negative relative conditional branch, - 32 KB */
    > - instr = ppc_inst(0x43ff8000);
    > - check(instr_is_branch_to_addr(&instr, addr - 0x8000));
    > + patch_instruction(iptr, ppc_inst(0x43ff8000));
    > + check(instr_is_branch_to_addr(iptr, addr - 0x8000));
    >
    > /* All condition code bits set & link */
    > flags = 0x3ff000 | BRANCH_SET_LINK;
    >
    > /* Branch to self */
    > err = create_cond_branch(&instr, iptr, addr, flags);
    > - check(instr_is_branch_to_addr(&instr, addr));
    > + patch_instruction(iptr, instr);
    > + check(instr_is_branch_to_addr(iptr, addr));
    >
    > /* Branch to self - 0x100 */
    > err = create_cond_branch(&instr, iptr, addr - 0x100, flags);
    > - check(instr_is_branch_to_addr(&instr, addr - 0x100));
    > + patch_instruction(iptr, instr);
    > + check(instr_is_branch_to_addr(iptr, addr - 0x100));
    >
    > /* Branch to self + 0x100 */
    > err = create_cond_branch(&instr, iptr, addr + 0x100, flags);
    > - check(instr_is_branch_to_addr(&instr, addr + 0x100));
    > + patch_instruction(iptr, instr);
    > + check(instr_is_branch_to_addr(iptr, addr + 0x100));
    >
    > /* Maximum relative negative offset, - 32 KB */
    > err = create_cond_branch(&instr, iptr, addr - 0x8000, flags);
    > - check(instr_is_branch_to_addr(&instr, addr - 0x8000));
    > + patch_instruction(iptr, instr);
    > + check(instr_is_branch_to_addr(iptr, addr - 0x8000));
    >
    > /* Out of range relative negative offset, - 32 KB + 4*/
    > err = create_cond_branch(&instr, iptr, addr - 0x8004, flags);
    > @@ -576,7 +586,8 @@ static void __init test_branch_bform(void)
    >
    > /* Check flags are masked correctly */
    > err = create_cond_branch(&instr, iptr, addr, 0xFFFFFFFC);
    > - check(instr_is_branch_to_addr(&instr, addr));
    > + patch_instruction(iptr, instr);
    > + check(instr_is_branch_to_addr(iptr, addr));
    > check(ppc_inst_equal(instr, ppc_inst(0x43FF0000)));
    > }
    >
    > --
    > 2.25.0
    >
    Reviewed by: Jordan Niethe <jniethe5@gmail.com>

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