From 9b5a7f4a2a8dcda461f9c7a6671150f4a8a902e8 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Thu, 31 Mar 2022 10:57:28 -0700 Subject: x86/configs: Add x86 debugging Kconfig fragment plus docs The kernel has a wide variety of debugging options to help catch and squash bugs. However, new debugging is added all the time and the existing options can be hard to find. Add a Kconfig fragment with the debugging options which tip maintainers expect to be used to test contributions. This should make it easier for contributors to test their code and find issues before submission. [ bp: Add to "make help" output, fix DEBUG_INFO selection as pointed out by Nathan Chancellor . ] Signed-off-by: Dave Hansen Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220331175728.299103A0@davehans-spike.ostc.intel.com --- arch/x86/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'arch') diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 63d50f65b828..1abd7cc9d6cd 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -313,5 +313,6 @@ define archhelp echo '' echo ' kvm_guest.config - Enable Kconfig items for running this kernel as a KVM guest' echo ' xen.config - Enable Kconfig items for running this kernel as a Xen guest' + echo ' x86_debug.config - Enable tip tree debugging options for testing' endef -- cgit v1.2.3 From aeb84412037b89e06f45e382f044da6f200e12f8 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Sun, 27 Feb 2022 11:59:18 -0800 Subject: x86/boot: Wrap literal addresses in absolute_pointer() GCC 11 (incorrectly[1]) assumes that literal values cast to (void *) should be treated like a NULL pointer with an offset, and raises diagnostics when doing bounds checking under -Warray-bounds. GCC 12 got "smarter" about finding these: In function 'rdfs8', inlined from 'vga_recalc_vertical' at /srv/code/arch/x86/boot/video-mode.c:124:29, inlined from 'set_mode' at /srv/code/arch/x86/boot/video-mode.c:163:3: /srv/code/arch/x86/boot/boot.h:114:9: warning: array subscript 0 is outside array bounds of 'u8[0]' {aka 'unsigned char[]'} [-Warray-bounds] 114 | asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); | ^~~ This has been solved in other places[2] already by using the recently added absolute_pointer() macro. Do the same here. [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578 [2] https://lore.kernel.org/all/20210912160149.2227137-1-linux@roeck-us.net/ Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Reviewed-by: Guenter Roeck Link: https://lore.kernel.org/r/20220227195918.705219-1-keescook@chromium.org --- arch/x86/boot/boot.h | 36 ++++++++++++++++++++++++------------ arch/x86/boot/main.c | 2 +- 2 files changed, 25 insertions(+), 13 deletions(-) (limited to 'arch') diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h index 34c9dbb6a47d..686a9d75a0e4 100644 --- a/arch/x86/boot/boot.h +++ b/arch/x86/boot/boot.h @@ -110,66 +110,78 @@ typedef unsigned int addr_t; static inline u8 rdfs8(addr_t addr) { + u8 *ptr = (u8 *)absolute_pointer(addr); u8 v; - asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); + asm volatile("movb %%fs:%1,%0" : "=q" (v) : "m" (*ptr)); return v; } static inline u16 rdfs16(addr_t addr) { + u16 *ptr = (u16 *)absolute_pointer(addr); u16 v; - asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr)); + asm volatile("movw %%fs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline u32 rdfs32(addr_t addr) { + u32 *ptr = (u32 *)absolute_pointer(addr); u32 v; - asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr)); + asm volatile("movl %%fs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline void wrfs8(u8 v, addr_t addr) { - asm volatile("movb %1,%%fs:%0" : "+m" (*(u8 *)addr) : "qi" (v)); + u8 *ptr = (u8 *)absolute_pointer(addr); + asm volatile("movb %1,%%fs:%0" : "+m" (*ptr) : "qi" (v)); } static inline void wrfs16(u16 v, addr_t addr) { - asm volatile("movw %1,%%fs:%0" : "+m" (*(u16 *)addr) : "ri" (v)); + u16 *ptr = (u16 *)absolute_pointer(addr); + asm volatile("movw %1,%%fs:%0" : "+m" (*ptr) : "ri" (v)); } static inline void wrfs32(u32 v, addr_t addr) { - asm volatile("movl %1,%%fs:%0" : "+m" (*(u32 *)addr) : "ri" (v)); + u32 *ptr = (u32 *)absolute_pointer(addr); + asm volatile("movl %1,%%fs:%0" : "+m" (*ptr) : "ri" (v)); } static inline u8 rdgs8(addr_t addr) { + u8 *ptr = (u8 *)absolute_pointer(addr); u8 v; - asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*(u8 *)addr)); + asm volatile("movb %%gs:%1,%0" : "=q" (v) : "m" (*ptr)); return v; } static inline u16 rdgs16(addr_t addr) { + u16 *ptr = (u16 *)absolute_pointer(addr); u16 v; - asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*(u16 *)addr)); + asm volatile("movw %%gs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline u32 rdgs32(addr_t addr) { + u32 *ptr = (u32 *)absolute_pointer(addr); u32 v; - asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*(u32 *)addr)); + asm volatile("movl %%gs:%1,%0" : "=r" (v) : "m" (*ptr)); return v; } static inline void wrgs8(u8 v, addr_t addr) { - asm volatile("movb %1,%%gs:%0" : "+m" (*(u8 *)addr) : "qi" (v)); + u8 *ptr = (u8 *)absolute_pointer(addr); + asm volatile("movb %1,%%gs:%0" : "+m" (*ptr) : "qi" (v)); } static inline void wrgs16(u16 v, addr_t addr) { - asm volatile("movw %1,%%gs:%0" : "+m" (*(u16 *)addr) : "ri" (v)); + u16 *ptr = (u16 *)absolute_pointer(addr); + asm volatile("movw %1,%%gs:%0" : "+m" (*ptr) : "ri" (v)); } static inline void wrgs32(u32 v, addr_t addr) { - asm volatile("movl %1,%%gs:%0" : "+m" (*(u32 *)addr) : "ri" (v)); + u32 *ptr = (u32 *)absolute_pointer(addr); + asm volatile("movl %1,%%gs:%0" : "+m" (*ptr) : "ri" (v)); } /* Note: these only return true/false, not a signed return value! */ diff --git a/arch/x86/boot/main.c b/arch/x86/boot/main.c index e3add857c2c9..c421af5a3cdc 100644 --- a/arch/x86/boot/main.c +++ b/arch/x86/boot/main.c @@ -33,7 +33,7 @@ static void copy_boot_params(void) u16 cl_offset; }; const struct old_cmdline * const oldcmd = - (const struct old_cmdline *)OLD_CL_ADDRESS; + absolute_pointer(OLD_CL_ADDRESS); BUILD_BUG_ON(sizeof(boot_params) != 4096); memcpy(&boot_params.hdr, &hdr, sizeof(hdr)); -- cgit v1.2.3