powerpc: allow minimum sized kernel stack frames

This affects only 64-bit ELFv2 kernels, and reduces the minimum
asm-created stack frame size from 112 to 32 byte on those kernels.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-16-npiggin@gmail.com

diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index 088f500896c78cba923446f9b6a5704e47dde30f..918547b93b5e9daac4a96f0c684a513c76dc369c 100644 (file)
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -602,7 +602,7 @@ start_here:
        lis     r1,init_thread_union@ha
        addi    r1,r1,init_thread_union@l
        li      r0,0
-       stwu    r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
+       stwu    r0,THREAD_SIZE-STACK_FRAME_MIN_SIZE(r1)
 
        bl      early_init      /* We have to do this with MMU on */
 

diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index f15cb9fdb692f18522ae27a5ea9da8c017b27f4c..63a85c16fef460b81dbacf7294b33945118c9aa7 100644 (file)
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -109,7 +109,7 @@ _GLOBAL(_start);
        lis     r1,init_thread_union@h
        ori     r1,r1,init_thread_union@l
        li      r0,0
-       stwu    r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
+       stwu    r0,THREAD_SIZE-STACK_FRAME_MIN_SIZE(r1)
 
        bl      early_init
 
@@ -1012,7 +1012,7 @@ _GLOBAL(start_secondary_47x)
         */
        lis     r1,temp_boot_stack@h
        ori     r1,r1,temp_boot_stack@l
-       addi    r1,r1,1024-STACK_FRAME_OVERHEAD
+       addi    r1,r1,1024-STACK_FRAME_MIN_SIZE
        li      r0,0
        stw     r0,0(r1)
        bl      mmu_init_secondary
@@ -1025,7 +1025,7 @@ _GLOBAL(start_secondary_47x)
        lwz     r1,TASK_STACK(r2)
 
        /* Current stack pointer */
-       addi    r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
+       addi    r1,r1,THREAD_SIZE-STACK_FRAME_MIN_SIZE
        li      r0,0
        stw     r0,0(r1)
 

diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index dedcc6fe2263a1d75159a12f5cd2f17ea384be15..b513d13bf79e41ad0dbc30d733e70848ef7d3b3c 100644 (file)
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -424,7 +424,7 @@ generic_secondary_common_init:
 
        /* Create a temp kernel stack for use before relocation is on.  */
        ld      r1,PACAEMERGSP(r13)
-       subi    r1,r1,STACK_FRAME_OVERHEAD
+       subi    r1,r1,STACK_FRAME_MIN_SIZE
 
        /* See if we need to call a cpu state restore handler */
        LOAD_REG_ADDR(r23, cur_cpu_spec)
@@ -780,7 +780,7 @@ _GLOBAL(pmac_secondary_start)
 
        /* Create a temp kernel stack for use before relocation is on.  */
        ld      r1,PACAEMERGSP(r13)
-       subi    r1,r1,STACK_FRAME_OVERHEAD
+       subi    r1,r1,STACK_FRAME_MIN_SIZE
 
        b       __secondary_start
 
@@ -958,7 +958,7 @@ start_here_multiplatform:
        LOAD_REG_IMMEDIATE(r1,THREAD_SIZE)
        add     r1,r3,r1
        li      r0,0
-       stdu    r0,-STACK_FRAME_OVERHEAD(r1)
+       stdu    r0,-STACK_FRAME_MIN_SIZE(r1)
 
        /*
         * Do very early kernel initializations, including initial hash table

diff --git a/arch/powerpc/kernel/head_85xx.S b/arch/powerpc/kernel/head_85xx.S
index 24f39abf81dff3766ed7be7f8f7537fb6f552b7b..d9bd377dec919a29aad28d9ce7655709674b4ae8 100644 (file)
--- a/arch/powerpc/kernel/head_85xx.S
+++ b/arch/powerpc/kernel/head_85xx.S
@@ -229,7 +229,7 @@ set_ivor:
        lis     r1,init_thread_union@h
        ori     r1,r1,init_thread_union@l
        li      r0,0
-       stwu    r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
+       stwu    r0,THREAD_SIZE-STACK_FRAME_MIN_SIZE(r1)
 
 #ifdef CONFIG_SMP
        stw     r24, TASK_CPU(r2)
@@ -1044,7 +1044,7 @@ __secondary_start:
        lwz     r1,TASK_STACK(r2)
 
        /* stack */
-       addi    r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
+       addi    r1,r1,THREAD_SIZE-STACK_FRAME_MIN_SIZE
        li      r0,0
        stw     r0,0(r1)
 

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 0b05f2be66b9fefcd00539cbd35e7ab0466f5188..cf546d0e5c4032828fca4ec243714f1b26a741b4 100644 (file)
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -537,7 +537,7 @@ start_here:
        ori     r0, r0, STACK_END_MAGIC@l
        stw     r0, 0(r1)
        li      r0,0
-       stwu    r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
+       stwu    r0,THREAD_SIZE-STACK_FRAME_MIN_SIZE(r1)
 
        lis     r6, swapper_pg_dir@ha
        tophys(r6,r6)

diff --git a/arch/powerpc/kernel/head_book3s_32.S b/arch/powerpc/kernel/head_book3s_32.S
index 519b606951675b46932d7b727a31c3a13176efc8..40854d092dd31405d1b2ed82442b5c4b2ec18150 100644 (file)
--- a/arch/powerpc/kernel/head_book3s_32.S
+++ b/arch/powerpc/kernel/head_book3s_32.S
@@ -840,7 +840,7 @@ __secondary_start:
        lwz     r1,TASK_STACK(r1)
 
        /* stack */
-       addi    r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
+       addi    r1,r1,THREAD_SIZE-STACK_FRAME_MIN_SIZE
        li      r0,0
        tophys(r3,r1)
        stw     r0,0(r3)
@@ -966,7 +966,7 @@ END_MMU_FTR_SECTION_IFCLR(MMU_FTR_HPTE_TABLE)
        lis     r1,init_thread_union@ha
        addi    r1,r1,init_thread_union@l
        li      r0,0
-       stwu    r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
+       stwu    r0,THREAD_SIZE-STACK_FRAME_MIN_SIZE(r1)
 /*
  * Do early platform-specific initialization,
  * and set up the MMU.

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 9ede61a5a469efb7f4252412c2a5c98c5f77c48b..c5b9ce8874834afccf3c822af51313cf5e544dcd 100644 (file)
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -210,7 +210,7 @@ static __always_inline void call_do_softirq(const void *sp)
                 PPC_LL "       %%r1, 0(%%r1)           ;"
                 : // Outputs
                 : // Inputs
-                  [sp] "b" (sp), [offset] "i" (THREAD_SIZE - STACK_FRAME_OVERHEAD),
+                  [sp] "b" (sp), [offset] "i" (THREAD_SIZE - STACK_FRAME_MIN_SIZE),
                   [callee] "i" (__do_softirq)
                 : // Clobbers
                   "lr", "xer", "ctr", "memory", "cr0", "cr1", "cr5", "cr6",
@@ -264,7 +264,7 @@ static __always_inline void call_do_irq(struct pt_regs *regs, void *sp)
                 : // Outputs
                   "+r" (r3)
                 : // Inputs
-                  [sp] "b" (sp), [offset] "i" (THREAD_SIZE - STACK_FRAME_OVERHEAD),
+                  [sp] "b" (sp), [offset] "i" (THREAD_SIZE - STACK_FRAME_MIN_SIZE),
                   [callee] "i" (__do_irq)
                 : // Clobbers
                   "lr", "xer", "ctr", "memory", "cr0", "cr1", "cr5", "cr6",

diff --git a/arch/powerpc/kernel/misc_32.S b/arch/powerpc/kernel/misc_32.S
index e5127b19fec29c56f94cca89757db567dc490ef5..daf8f87d2372853b91be6810edb20b0663a1441d 100644 (file)
--- a/arch/powerpc/kernel/misc_32.S
+++ b/arch/powerpc/kernel/misc_32.S
@@ -382,7 +382,7 @@ EXPORT_SYMBOL(__bswapdi2)
 _GLOBAL(start_secondary_resume)
        /* Reset stack */
        rlwinm  r1, r1, 0, 0, 31 - THREAD_SHIFT
-       addi    r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
+       addi    r1,r1,THREAD_SIZE-STACK_FRAME_MIN_SIZE
        li      r3,0
        stw     r3,0(r1)                /* Zero the stack frame pointer */
        bl      start_secondary

diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index 36184cada00b1107a67885da80dc6a96dfa5a4e8..4bb6dd30c55683d1a577ead64dac4e3d08dacef3 100644 (file)
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -384,7 +384,7 @@ _GLOBAL(kexec_sequence)
        std     r0,16(r1)
 
        /* switch stacks to newstack -- &kexec_stack.stack */
-       stdu    r1,THREAD_SIZE-STACK_FRAME_OVERHEAD(r3)
+       stdu    r1,THREAD_SIZE-STACK_FRAME_MIN_SIZE(r3)
        mr      r1,r3
 
        li      r0,0
@@ -401,7 +401,7 @@ _GLOBAL(kexec_sequence)
        std     r26,-48(r1)
        std     r25,-56(r1)
 
-       stdu    r1,-STACK_FRAME_OVERHEAD-64(r1)
+       stdu    r1,-STACK_FRAME_MIN_SIZE-64(r1)
 
        /* save args into preserved regs */
        mr      r31,r3                  /* newstack (both) */

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 9446bee8ca32ab816c08528f7da935071b1ccc84..edb46d0806ef7c261959da9e3d8ade64bdcb2e4f 100644 (file)
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2180,7 +2180,7 @@ int validate_sp_size(unsigned long sp, struct task_struct *p,
 
 int validate_sp(unsigned long sp, struct task_struct *p)
 {
-       return validate_sp_size(sp, p, STACK_FRAME_OVERHEAD);
+       return validate_sp_size(sp, p, STACK_FRAME_MIN_SIZE);
 }
 
 static unsigned long ___get_wchan(struct task_struct *p)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 0da6e59161cd494678ebabce5feb8dd72e5fe017..6b90f10a6c819b2cf95accf64950e23ce92cc538 100644 (file)
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1249,7 +1249,7 @@ static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle)
 #ifdef CONFIG_PPC64
        paca_ptrs[cpu]->__current = idle;
        paca_ptrs[cpu]->kstack = (unsigned long)task_stack_page(idle) +
-                                THREAD_SIZE - STACK_FRAME_OVERHEAD;
+                                THREAD_SIZE - STACK_FRAME_MIN_SIZE;
 #endif
        task_thread_info(idle)->cpu = cpu;
        secondary_current = current_set[cpu] = idle;

diff --git a/arch/powerpc/kernel/stacktrace.c b/arch/powerpc/kernel/stacktrace.c
index 1dbbf30f265e0a5dcea05856294d1be7f78e9a5f..5de8597eaab8dc428828abb0c6fba244e62fe23b 100644 (file)
--- a/arch/powerpc/kernel/stacktrace.c
+++ b/arch/powerpc/kernel/stacktrace.c
@@ -94,7 +94,7 @@ int __no_sanitize_address arch_stack_walk_reliable(stack_trace_consume_fn consum
                 * idle tasks have a custom stack layout,
                 * c.f. cpu_idle_thread_init().
                 */
-               stack_end -= STACK_FRAME_OVERHEAD;
+               stack_end -= STACK_FRAME_MIN_SIZE;
        }
 
        if (task == current)