[PATCH 06/14] powerpc: Add tests of the code patching routines
Michael Ellerman
michael at ellerman.id.au
Tue Jun 24 11:32:32 EST 2008
Add tests of the existing code patching routines, as well as the new
routines added in the last commit. The self-tests are run late in boot
when CONFIG_CODE_PATCHING_SELFTEST=y, which depends on DEBUG_KERNEL=y.
Signed-off-by: Michael Ellerman <michael at ellerman.id.au>
---
arch/powerpc/Kconfig.debug | 5 +
arch/powerpc/lib/code-patching.c | 298 ++++++++++++++++++++++++++++++++++++++
2 files changed, 303 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index a7d24e6..dc58939 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -57,6 +57,11 @@ config KGDB
debugger. See <http://kgdb.sourceforge.net/> for more information.
Unless you are intending to debug the kernel, say N here.
+config CODE_PATCHING_SELFTEST
+ bool "Run self-tests of the code-patching code."
+ depends on DEBUG_KERNEL
+ default n
+
choice
prompt "Serial Port"
depends on KGDB
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 27957c4..0559fe0 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -8,6 +8,9 @@
*/
#include <linux/kernel.h>
+#include <linux/vmalloc.h>
+#include <linux/init.h>
+#include <asm/page.h>
#include <asm/code-patching.h>
@@ -148,3 +151,298 @@ unsigned int translate_branch(const unsigned int *dest, const unsigned int *src)
return 0;
}
+
+
+#ifdef CONFIG_CODE_PATCHING_SELFTEST
+
+static void __init test_trampoline(void)
+{
+ asm ("nop;\n");
+}
+
+#define check(x) \
+ if (!(x)) printk("code-patching: test failed at line %d\n", __LINE__);
+
+static void __init test_branch_iform(void)
+{
+ unsigned int instr;
+ unsigned long addr;
+
+ addr = (unsigned long)&instr;
+
+ /* The simplest case, branch to self, no flags */
+ check(instr_is_branch_iform(0x48000000));
+ /* All bits of target set, and flags */
+ check(instr_is_branch_iform(0x4bffffff));
+ /* High bit of opcode set, which is wrong */
+ check(!instr_is_branch_iform(0xcbffffff));
+ /* Middle bits of opcode set, which is wrong */
+ check(!instr_is_branch_iform(0x7bffffff));
+
+ /* Simplest case, branch to self with link */
+ check(instr_is_branch_iform(0x48000001));
+ /* All bits of targets set */
+ check(instr_is_branch_iform(0x4bfffffd));
+ /* Some bits of targets set */
+ check(instr_is_branch_iform(0x4bff00fd));
+ /* Must be a valid branch to start with */
+ check(!instr_is_branch_iform(0x7bfffffd));
+
+ /* Absolute branch to 0x100 */
+ instr = 0x48000103;
+ check(instr_is_branch_to_addr(&instr, 0x100));
+ /* Absolute branch to 0x420fc */
+ instr = 0x480420ff;
+ check(instr_is_branch_to_addr(&instr, 0x420fc));
+ /* Maximum positive relative branch, + 20MB - 4B */
+ instr = 0x49fffffc;
+ check(instr_is_branch_to_addr(&instr, addr + 0x1FFFFFC));
+ /* Smallest negative relative branch, - 4B */
+ instr = 0x4bfffffc;
+ check(instr_is_branch_to_addr(&instr, addr - 4));
+ /* Largest negative relative branch, - 32 MB */
+ instr = 0x4a000000;
+ check(instr_is_branch_to_addr(&instr, addr - 0x2000000));
+
+ /* Branch to self, with link */
+ instr = create_branch(&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);
+ check(instr_is_branch_to_addr(&instr, addr - 0x100));
+
+ /* Branch to self + 0x100, no link */
+ instr = create_branch(&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);
+ 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);
+
+ /* Out of range relative positive offset, + 32 MB */
+ instr = create_branch(&instr, addr + 0x2000000, BRANCH_SET_LINK);
+ check(instr == 0);
+
+ /* Unaligned target */
+ instr = create_branch(&instr, addr + 3, BRANCH_SET_LINK);
+ check(instr == 0);
+
+ /* Check flags are masked correctly */
+ instr = create_branch(&instr, addr, 0xFFFFFFFC);
+ check(instr_is_branch_to_addr(&instr, addr));
+ check(instr == 0x48000000);
+}
+
+static void __init test_create_function_call(void)
+{
+ unsigned int *iptr;
+ unsigned long dest;
+
+ /* 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));
+ check(instr_is_branch_to_addr(iptr, dest));
+}
+
+static void __init test_branch_bform(void)
+{
+ unsigned long addr;
+ unsigned int *iptr, instr, flags;
+
+ iptr = &instr;
+ addr = (unsigned long)iptr;
+
+ /* The simplest case, branch to self, no flags */
+ check(instr_is_branch_bform(0x40000000));
+ /* All bits of target set, and flags */
+ check(instr_is_branch_bform(0x43ffffff));
+ /* High bit of opcode set, which is wrong */
+ check(!instr_is_branch_bform(0xc3ffffff));
+ /* Middle bits of opcode set, which is wrong */
+ check(!instr_is_branch_bform(0x7bffffff));
+
+ /* Absolute conditional branch to 0x100 */
+ instr = 0x43ff0103;
+ check(instr_is_branch_to_addr(&instr, 0x100));
+ /* Absolute conditional branch to 0x20fc */
+ instr = 0x43ff20ff;
+ check(instr_is_branch_to_addr(&instr, 0x20fc));
+ /* Maximum positive relative conditional branch, + 32 KB - 4B */
+ instr = 0x43ff7ffc;
+ check(instr_is_branch_to_addr(&instr, addr + 0x7FFC));
+ /* Smallest negative relative conditional branch, - 4B */
+ instr = 0x43fffffc;
+ check(instr_is_branch_to_addr(&instr, addr - 4));
+ /* Largest negative relative conditional branch, - 32 KB */
+ instr = 0x43ff8000;
+ check(instr_is_branch_to_addr(&instr, addr - 0x8000));
+
+ /* All condition code bits set & link */
+ flags = 0x3ff000 | BRANCH_SET_LINK;
+
+ /* Branch to self */
+ instr = create_cond_branch(iptr, addr, flags);
+ check(instr_is_branch_to_addr(&instr, addr));
+
+ /* Branch to self - 0x100 */
+ instr = create_cond_branch(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);
+ check(instr_is_branch_to_addr(&instr, addr + 0x100));
+
+ /* Maximum relative negative offset, - 32 KB */
+ instr = create_cond_branch(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);
+
+ /* Out of range relative positive offset, + 32 KB */
+ instr = create_cond_branch(iptr, addr + 0x8000, flags);
+ check(instr == 0);
+
+ /* Unaligned target */
+ instr = create_cond_branch(iptr, addr + 3, flags);
+ check(instr == 0);
+
+ /* Check flags are masked correctly */
+ instr = create_cond_branch(iptr, addr, 0xFFFFFFFC);
+ check(instr_is_branch_to_addr(&instr, addr));
+ check(instr == 0x43FF0000);
+}
+
+static void __init test_translate_branch(void)
+{
+ unsigned long addr;
+ unsigned int *p, *q;
+ void *buf;
+
+ buf = vmalloc(PAGE_ALIGN(0x2000000 + 1));
+ check(buf);
+ if (!buf)
+ return;
+
+ /* Simple case, branch to self moved a little */
+ p = buf;
+ addr = (unsigned long)p;
+ patch_branch(p, addr, 0);
+ check(instr_is_branch_to_addr(p, addr));
+ q = p + 1;
+ patch_instruction(q, translate_branch(q, p));
+ check(instr_is_branch_to_addr(q, addr));
+
+ /* Maximum negative case, move b . to addr + 32 MB */
+ p = buf;
+ addr = (unsigned long)p;
+ patch_branch(p, addr, 0);
+ q = buf + 0x2000000;
+ patch_instruction(q, translate_branch(q, p));
+ check(instr_is_branch_to_addr(p, addr));
+ check(instr_is_branch_to_addr(q, addr));
+ check(*q == 0x4a000000);
+
+ /* Maximum positive case, move x to x - 32 MB + 4 */
+ p = buf + 0x2000000;
+ addr = (unsigned long)p;
+ patch_branch(p, addr, 0);
+ q = buf + 4;
+ patch_instruction(q, translate_branch(q, p));
+ check(instr_is_branch_to_addr(p, addr));
+ check(instr_is_branch_to_addr(q, addr));
+ check(*q == 0x49fffffc);
+
+ /* Jump to x + 16 MB moved to x + 20 MB */
+ p = buf;
+ addr = 0x1000000 + (unsigned long)buf;
+ patch_branch(p, addr, BRANCH_SET_LINK);
+ q = buf + 0x1400000;
+ patch_instruction(q, translate_branch(q, p));
+ check(instr_is_branch_to_addr(p, addr));
+ check(instr_is_branch_to_addr(q, addr));
+
+ /* Jump to x + 16 MB moved to x - 16 MB + 4 */
+ p = buf + 0x1000000;
+ addr = 0x2000000 + (unsigned long)buf;
+ patch_branch(p, addr, 0);
+ q = buf + 4;
+ patch_instruction(q, translate_branch(q, p));
+ check(instr_is_branch_to_addr(p, addr));
+ check(instr_is_branch_to_addr(q, addr));
+
+
+ /* Conditional branch tests */
+
+ /* Simple case, branch to self moved a little */
+ p = buf;
+ addr = (unsigned long)p;
+ patch_instruction(p, create_cond_branch(p, addr, 0));
+ check(instr_is_branch_to_addr(p, addr));
+ q = p + 1;
+ patch_instruction(q, translate_branch(q, p));
+ 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));
+ q = buf + 0x8000;
+ patch_instruction(q, translate_branch(q, p));
+ check(instr_is_branch_to_addr(p, addr));
+ check(instr_is_branch_to_addr(q, addr));
+ check(*q == 0x43ff8000);
+
+ /* 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));
+ q = buf + 4;
+ patch_instruction(q, translate_branch(q, p));
+ check(instr_is_branch_to_addr(p, addr));
+ check(instr_is_branch_to_addr(q, addr));
+ check(*q == 0x43ff7ffc);
+
+ /* 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));
+ q = buf + 0x5000;
+ patch_instruction(q, translate_branch(q, p));
+ 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));
+ q = buf + 4;
+ patch_instruction(q, translate_branch(q, p));
+ check(instr_is_branch_to_addr(p, addr));
+ check(instr_is_branch_to_addr(q, addr));
+
+ /* Free the buffer we were using */
+ vfree(buf);
+}
+
+static int __init test_code_patching(void)
+{
+ printk(KERN_DEBUG "Running code patching self-tests ...\n");
+
+ test_branch_iform();
+ test_branch_bform();
+ test_create_function_call();
+ test_translate_branch();
+
+ return 0;
+}
+late_initcall(test_code_patching);
+
+#endif /* CONFIG_CODE_PATCHING_SELFTEST */
--
1.5.5
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