[coreboot-gerrit] Change in coreboot[master]: x86: mmio: Qualify variables as volatile

[Paul Menzel (Code Review)]

Paul Menzel has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/62828 )

Change subject: x86: mmio: Qualify variables as volatile
......................................................................

x86: mmio: Qualify variables as volatile

GCC 12 warns about out-of-bounds array subscripts:

```
$ make V=1 # emulation/qemu-i440fx
[…]
x86_64-linux-gnu-gcc-12 -MMD -Isrc -Isrc/include -Isrc/commonlib/include -Isrc/commonlib/bsd/include -Ibuild -I3rdparty/vboot/firmware/include -include src/include/kconfig.h -include src/include/rules.h -include src/commonlib/bsd/include/commonlib/bsd/compiler.h -I3rdparty -D__BUILD_DIR__="build" -Isrc/arch/x86/include -D__ARCH_x86_32__ -pipe -g -nostdinc -std=gnu11 -nostdlib -Wall -Wundef -Wstrict-prototypes -Wmissing-prototypes -Wwrite-strings -Wredundant-decls -Wno-trigraphs -Wimplicit-fallthrough -Wshadow -Wdate-time -Wtype-limits -Wvla -Wdangling-else -fno-common -ffreestanding -fno-builtin -fomit-frame-pointer -fstrict-aliasing -ffunction-sections -fdata-sections -fno-pie -Wno-packed-not-aligned -fconserve-stack -Wnull-dereference -Wreturn-type -Wlogical-op -Wduplicated-cond -Wno-unused-but-set-variable -Werror -Os -Wno-address-of-packed-member -m32 -Wl,-b,elf32-i386 -Wl,-melf_i386 -m32  -fuse-ld=bfd -fno-stack-protector -Wl,--build-id=none -fno-delete-null-pointer-checks -Wlogical-op -march=i686 -mno-mmx -MT build/bootblock/cpu/x86/lapic/lapic.o -D__BOOTBLOCK__ -c -o build/bootblock/cpu/x86/lapic/lapic.o src/cpu/x86/lapic/lapic.c
In file included from src/include/cpu/x86/lapic.h:4,
                 from src/cpu/x86/lapic/lapic.c:5:
In function 'read32',
    inlined from 'xapic_read' at src/include/cpu/x86/lapic.h:13:9,
    inlined from 'lapic_read' at src/include/cpu/x86/lapic.h:80:10,
    inlined from 'lapicid' at src/include/cpu/x86/lapic.h:138:21,
    inlined from 'enable_lapic' at src/cpu/x86/lapic/lapic.c:41:3:
src/arch/x86/include/arch/mmio.h:20:16: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   20 |         return *((volatile uint32_t *)(addr));
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'read32',
    inlined from 'xapic_read' at src/include/cpu/x86/lapic.h:13:9,
    inlined from 'lapic_update32' at src/include/cpu/x86/lapic.h:103:11,
    inlined from 'setup_lapic_interrupts' at src/cpu/x86/lapic/lapic.c:73:2:
src/arch/x86/include/arch/mmio.h:20:16: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   20 |         return *((volatile uint32_t *)(addr));
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'write32',
    inlined from 'xapic_write' at src/include/cpu/x86/lapic.h:18:2,
    inlined from 'lapic_update32' at src/include/cpu/x86/lapic.h:106:3,
    inlined from 'setup_lapic_interrupts' at src/cpu/x86/lapic/lapic.c:73:2:
src/arch/x86/include/arch/mmio.h:40:40: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   40 |         *((volatile uint32_t *)(addr)) = value;
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
In function 'read32',
    inlined from 'xapic_read' at src/include/cpu/x86/lapic.h:13:9,
    inlined from 'lapic_update32' at src/include/cpu/x86/lapic.h:103:11,
    inlined from 'setup_lapic_interrupts' at src/cpu/x86/lapic/lapic.c:77:2:
src/arch/x86/include/arch/mmio.h:20:16: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   20 |         return *((volatile uint32_t *)(addr));
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'write32',
    inlined from 'xapic_write' at src/include/cpu/x86/lapic.h:18:2,
    inlined from 'lapic_update32' at src/include/cpu/x86/lapic.h:106:3,
    inlined from 'setup_lapic_interrupts' at src/cpu/x86/lapic/lapic.c:77:2:
src/arch/x86/include/arch/mmio.h:40:40: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   40 |         *((volatile uint32_t *)(addr)) = value;
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
In function 'read32',
    inlined from 'xapic_read' at src/include/cpu/x86/lapic.h:13:9,
    inlined from 'lapic_update32' at src/include/cpu/x86/lapic.h:103:11,
    inlined from 'setup_lapic_interrupts' at src/cpu/x86/lapic/lapic.c:86:3:
src/arch/x86/include/arch/mmio.h:20:16: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   20 |         return *((volatile uint32_t *)(addr));
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'write32',
    inlined from 'xapic_write' at src/include/cpu/x86/lapic.h:18:2,
    inlined from 'lapic_update32' at src/include/cpu/x86/lapic.h:106:3,
    inlined from 'setup_lapic_interrupts' at src/cpu/x86/lapic/lapic.c:86:3:
src/arch/x86/include/arch/mmio.h:40:40: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   40 |         *((volatile uint32_t *)(addr)) = value;
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
In function 'read32',
    inlined from 'xapic_read' at src/include/cpu/x86/lapic.h:13:9,
    inlined from 'lapic_update32' at src/include/cpu/x86/lapic.h:103:11,
    inlined from 'setup_lapic_interrupts' at src/cpu/x86/lapic/lapic.c:84:3:
src/arch/x86/include/arch/mmio.h:20:16: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   20 |         return *((volatile uint32_t *)(addr));
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'write32',
    inlined from 'xapic_write' at src/include/cpu/x86/lapic.h:18:2,
    inlined from 'lapic_update32' at src/include/cpu/x86/lapic.h:106:3,
    inlined from 'setup_lapic_interrupts' at src/cpu/x86/lapic/lapic.c:84:3:
src/arch/x86/include/arch/mmio.h:40:40: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   40 |         *((volatile uint32_t *)(addr)) = value;
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
In function 'read32',
    inlined from 'xapic_read' at src/include/cpu/x86/lapic.h:13:9,
    inlined from 'lapic_update32' at src/include/cpu/x86/lapic.h:103:11,
    inlined from 'setup_lapic_interrupts' at src/cpu/x86/lapic/lapic.c:89:2:
src/arch/x86/include/arch/mmio.h:20:16: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   20 |         return *((volatile uint32_t *)(addr));
      |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'write32',
    inlined from 'xapic_write' at src/include/cpu/x86/lapic.h:18:2,
    inlined from 'lapic_update32' at src/include/cpu/x86/lapic.h:106:3,
    inlined from 'setup_lapic_interrupts' at src/cpu/x86/lapic/lapic.c:89:2:
src/arch/x86/include/arch/mmio.h:40:40: error: array subscript 0 is outside array bounds of 'const volatile void[0]' [-Werror=array-bounds]
   40 |         *((volatile uint32_t *)(addr)) = value;
      |         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
cc1: all warnings being treated as errors

```

Fix it, by qualifying the variables as volatile.

Found-by: gcc-12 (Debian 12-20220313-1) 12.0.1 20220314 (experimental) [master r12-7638-g823b3b79cd2]
Link: https://mail.coreboot.org/hyperkitty/list/[e-mail]/thread/IDX6Q...
Solution-by: Nico Huber
Change-Id: If2769bb0e365aa9d82d709d3715323819bc9de6e
Signed-off-by: Paul Menzel 
---
M src/arch/x86/include/arch/mmio.h
1 file changed, 8 insertions(+), 8 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/28/62828/1

diff --git a/src/arch/x86/include/arch/mmio.h b/src/arch/x86/include/arch/mmio.h
index c2aa0fb..b94b84a 100644
--- a/src/arch/x86/include/arch/mmio.h
+++ b/src/arch/x86/include/arch/mmio.h
@@ -5,42 +5,42 @@

#include <stdint.h>

-static __always_inline uint8_t read8(const volatile void *addr)
+static __always_inline uint8_t read8(const volatile void *volatile addr)
 {
    return *((volatile uint8_t *)(addr));
 }

-static __always_inline uint16_t read16(const volatile void *addr)
+static __always_inline uint16_t read16(const volatile void *volatile addr)
 {
    return *((volatile uint16_t *)(addr));
 }

-static __always_inline uint32_t read32(const volatile void *addr)
+static __always_inline uint32_t read32(const volatile void *volatile addr)
 {
    return *((volatile uint32_t *)(addr));
 }

-static __always_inline uint64_t read64(const volatile void *addr)
+static __always_inline uint64_t read64(const volatile void *volatile addr)
 {
    return *((volatile uint64_t *)(addr));
 }

-static __always_inline void write8(volatile void *addr, uint8_t value)
+static __always_inline void write8(volatile void *volatile addr, uint8_t value)
 {
    *((volatile uint8_t *)(addr)) = value;
 }

-static __always_inline void write16(volatile void *addr, uint16_t value)
+static __always_inline void write16(volatile void *volatile addr, uint16_t value)
 {
    *((volatile uint16_t *)(addr)) = value;
 }

-static __always_inline void write32(volatile void *addr, uint32_t value)
+static __always_inline void write32(volatile void *volatile addr, uint32_t value)
 {
    *((volatile uint32_t *)(addr)) = value;
 }

-static __always_inline void write64(volatile void *addr, uint64_t value)
+static __always_inline void write64(volatile void *volatile addr, uint64_t value)
 {
    *((volatile uint64_t *)(addr)) = value;
 }