Re: [PATCH v2 07/12] powerpc/lib/code-patching: Don't use struct 'ppc_inst' for runnable code in tests.
From: Jordan Niethe
Date: Mon Jun 14 2021 - 23:43:11 EST
On Thu, May 20, 2021 at 11:50 PM Christophe Leroy
<christophe.leroy@xxxxxxxxxx> 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@xxxxxxxxxx>
> ---
> 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@xxxxxxxxx>