powerpc: split validate_sp into two functions

Most callers just want to validate an arbitrary kernel stack pointer,
some need a particular size. Make the size case the exceptional one
with an extra function.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-15-npiggin@gmail.com

diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index 631802999d5988f1aa7bf2f993a794563454ca06..e96c9b8c2a60bdac9fb2a833c48bf241a21fa4c7 100644 (file)
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -374,9 +374,18 @@ static inline unsigned long __pack_fe01(unsigned int fpmode)
 
 #endif
 
-/* Check that a certain kernel stack pointer is valid in task_struct p */
-int validate_sp(unsigned long sp, struct task_struct *p,
-                       unsigned long nbytes);
+/*
+ * Check that a certain kernel stack pointer is a valid (minimum sized)
+ * stack frame in task_struct p.
+ */
+int validate_sp(unsigned long sp, struct task_struct *p);
+
+/*
+ * validate the stack frame of a particular minimum size, used for when we are
+ * looking at a certain object in the stack beyond the minimum.
+ */
+int validate_sp_size(unsigned long sp, struct task_struct *p,
+                    unsigned long nbytes);
 
 /*
  * Prefetch macros.

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 096b6ea52378c79a7eb46070d96d3ab00958260f..9446bee8ca32ab816c08528f7da935071b1ccc84 100644 (file)
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2157,9 +2157,12 @@ static inline int valid_emergency_stack(unsigned long sp, struct task_struct *p,
        return 0;
 }
 
-
-int validate_sp(unsigned long sp, struct task_struct *p,
-                      unsigned long nbytes)
+/*
+ * validate the stack frame of a particular minimum size, used for when we are
+ * looking at a certain object in the stack beyond the minimum.
+ */
+int validate_sp_size(unsigned long sp, struct task_struct *p,
+                    unsigned long nbytes)
 {
        unsigned long stack_page = (unsigned long)task_stack_page(p);
 
@@ -2175,7 +2178,10 @@ int validate_sp(unsigned long sp, struct task_struct *p,
        return valid_emergency_stack(sp, p, nbytes);
 }
 
-EXPORT_SYMBOL(validate_sp);
+int validate_sp(unsigned long sp, struct task_struct *p)
+{
+       return validate_sp_size(sp, p, STACK_FRAME_OVERHEAD);
+}
 
 static unsigned long ___get_wchan(struct task_struct *p)
 {
@@ -2183,13 +2189,12 @@ static unsigned long ___get_wchan(struct task_struct *p)
        int count = 0;
 
        sp = p->thread.ksp;
-       if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD))
+       if (!validate_sp(sp, p))
                return 0;
 
        do {
                sp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
-               if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD) ||
-                   task_is_running(p))
+               if (!validate_sp(sp, p) || task_is_running(p))
                        return 0;
                if (count > 0) {
                        ip = READ_ONCE_NOCHECK(((unsigned long *)sp)[STACK_FRAME_LR_SAVE]);
@@ -2243,7 +2248,7 @@ void __no_sanitize_address show_stack(struct task_struct *tsk,
        lr = 0;
        printk("%sCall Trace:\n", loglvl);
        do {
-               if (!validate_sp(sp, tsk, STACK_FRAME_OVERHEAD))
+               if (!validate_sp(sp, tsk))
                        break;
 
                stack = (unsigned long *) sp;
@@ -2270,7 +2275,7 @@ void __no_sanitize_address show_stack(struct task_struct *tsk,
                 * could hold a pt_regs, if that does not fit then it can't
                 * have regs.
                 */
-               if (validate_sp(sp, tsk, STACK_SWITCH_FRAME_SIZE)
+               if (validate_sp_size(sp, tsk, STACK_SWITCH_FRAME_SIZE)
                    && stack[STACK_INT_FRAME_MARKER_LONGS] == STACK_FRAME_REGS_MARKER) {
                        struct pt_regs *regs = (struct pt_regs *)
                                (sp + STACK_INT_FRAME_REGS);

diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c
index 453ac317a6cf508c2473a2c0c7d09c716ea332c3..1dbbf30f265e0a5dcea05856294d1be7f78e9a5f 100644 (file)
--- a/arch/powerpc/kernel/stacktrace.c
+++ b/arch/powerpc/kernel/stacktrace.c
@@ -43,7 +43,7 @@ void __no_sanitize_address arch_stack_walk(stack_trace_consume_fn consume_entry,
                unsigned long *stack = (unsigned long *) sp;
                unsigned long newsp, ip;
 
-               if (!validate_sp(sp, task, STACK_FRAME_OVERHEAD))
+               if (!validate_sp(sp, task))
                        return;
 
                newsp = stack[0];

diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c
index b01497ed51738673ea3aef82305fa9e45b95011a..6b4434dd0ff307c5673e0bd0a8ff25e38023c005 100644 (file)
--- a/arch/powerpc/perf/callchain.c
+++ b/arch/powerpc/perf/callchain.c
@@ -27,7 +27,7 @@ static int valid_next_sp(unsigned long sp, unsigned long prev_sp)
 {
        if (sp & 0xf)
                return 0;               /* must be 16-byte aligned */
-       if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
+       if (!validate_sp(sp, current))
                return 0;
        if (sp >= prev_sp + STACK_FRAME_MIN_SIZE)
                return 1;
@@ -53,7 +53,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
        sp = regs->gpr[1];
        perf_callchain_store(entry, perf_instruction_pointer(regs));
 
-       if (!validate_sp(sp, current, STACK_FRAME_OVERHEAD))
+       if (!validate_sp(sp, current))
                return;
 
        for (;;) {
@@ -61,7 +61,7 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
                next_sp = fp[0];
 
                if (next_sp == sp + STACK_INT_FRAME_SIZE &&
-                   validate_sp(sp, current, STACK_INT_FRAME_SIZE) &&
+                   validate_sp_size(sp, current, STACK_INT_FRAME_SIZE) &&
                    fp[STACK_INT_FRAME_MARKER_LONGS] == STACK_FRAME_REGS_MARKER) {
                        /*
                         * This looks like an interrupt frame for an