[tip: x86/misc] x86/mm: Cleanup the control_va_addr_alignment() __setup handler

[tip-bot2 for Randy Dunlap]

The following commit has been merged into the x86/misc branch of tip:

Commit-ID:     1ef64b1e89e6d4018da46e08ffc32779a31160c7
Gitweb:        https://git.kernel.org/tip/1ef64b1e89e6d4018da46e08ffc32779a31160c7
Author:        Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
AuthorDate:    Mon, 14 Mar 2022 17:10:45 -07:00
Committer:     Borislav Petkov <bp@xxxxxxx>
CommitterDate: Wed, 04 May 2022 18:20:42 +02:00

x86/mm: Cleanup the control_va_addr_alignment() __setup handler

Clean up control_va_addr_alignment():

a. Make '=' required instead of optional (as documented).
b. Print a warning if an invalid option value is used.
c. Return 1 from the __setup handler when an invalid option value is
   used. This prevents the kernel from polluting init's (limited)
   environment space with the entire string.

Fixes: dfb09f9b7ab0 ("x86, amd: Avoid cache aliasing penalties on AMD family 15h")
Reported-by: Igor Zhbanov <i.zhbanov@xxxxxxxxxxxx>
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Link: https://lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@xxxxxxxxxxxx
Link: https://lore.kernel.org/r/20220315001045.7680-1-rdunlap@xxxxxxxxxxxxx
---
 arch/x86/kernel/sys_x86_64.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 660b788..8cc653f 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -68,9 +68,6 @@ static int __init control_va_addr_alignment(char *str)
 	if (*str == 0)
 		return 1;
 
-	if (*str == '=')
-		str++;
-
 	if (!strcmp(str, "32"))
 		va_align.flags = ALIGN_VA_32;
 	else if (!strcmp(str, "64"))
@@ -80,11 +77,11 @@ static int __init control_va_addr_alignment(char *str)
 	else if (!strcmp(str, "on"))
 		va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
 	else
-		return 0;
+		pr_warn("invalid option value: 'align_va_addr=%s'\n", str);
 
 	return 1;
 }
-__setup("align_va_addr", control_va_addr_alignment);
+__setup("align_va_addr=", control_va_addr_alignment);
 
 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
 		unsigned long, prot, unsigned long, flags,