Commit 59c80f05 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'x86_urgent_for_v5.19_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 fixes from Borislav Petkov:

 - Improve the check whether the kernel supports WP mappings so that it
   can accomodate a XenPV guest due to how the latter is setting up the
   PAT machinery

  - Now that the retbleed nightmare is public, here's the first round of
    fallout fixes:

      * Fix a build failure on 32-bit due to missing include

      * Remove an untraining point in espfix64 return path

      * other small cleanups

* tag 'x86_urgent_for_v5.19_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/bugs: Remove apostrophe typo
  um: Add missing apply_returns()
  x86/entry: Remove UNTRAIN_RET from native_irq_return_ldt
  x86/bugs: Mark retbleed_strings static
  x86/pat: Fix x86_has_pat_wp()
  x86/asm/32: Fix ANNOTATE_UNRET_SAFE use on 32-bit
parents 2eccaca7 bcf16315

arch/um/kernel/um_arch.c

+4 −0
Original line number Diff line number Diff line
@@ -432,6 +432,10 @@ void apply_retpolines(s32 *start, s32 *end) 
{

}



void apply_returns(s32 *start, s32 *end)

{

}



void apply_alternatives(struct alt_instr *start, struct alt_instr *end)

{

}

arch/x86/entry/entry_64.S

+0 −1
Original line number Diff line number Diff line
@@ -727,7 +727,6 @@ native_irq_return_ldt: 
	pushq	%rdi				/* Stash user RDI */

	swapgs					/* to kernel GS */

	SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi	/* to kernel CR3 */

	UNTRAIN_RET



	movq	PER_CPU_VAR(espfix_waddr), %rdi

	movq	%rax, (0*8)(%rdi)		/* user RAX */

arch/x86/kernel/cpu/bugs.c

+2 −2
Original line number Diff line number Diff line
@@ -793,7 +793,7 @@ enum retbleed_mitigation_cmd { 
	RETBLEED_CMD_IBPB,

};



const char * const retbleed_strings[] = {

static const char * const retbleed_strings[] = {

	[RETBLEED_MITIGATION_NONE]	= "Vulnerable",

	[RETBLEED_MITIGATION_UNRET]	= "Mitigation: untrained return thunk",

	[RETBLEED_MITIGATION_IBPB]	= "Mitigation: IBPB",
@@ -1181,7 +1181,7 @@ spectre_v2_user_select_mitigation(void) 
	if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET) {

		if (mode != SPECTRE_V2_USER_STRICT &&

		    mode != SPECTRE_V2_USER_STRICT_PREFERRED)

			pr_info("Selecting STIBP always-on mode to complement retbleed mitigation'\n");

			pr_info("Selecting STIBP always-on mode to complement retbleed mitigation\n");

		mode = SPECTRE_V2_USER_STRICT_PREFERRED;

	}

arch/x86/kernel/head_32.S

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <asm/cpufeatures.h>

#include <asm/percpu.h>

#include <asm/nops.h>

#include <asm/nospec-branch.h>

#include <asm/bootparam.h>

#include <asm/export.h>

#include <asm/pgtable_32.h>

arch/x86/mm/init.c

+12 −2
Original line number Diff line number Diff line
@@ -77,10 +77,20 @@ static uint8_t __pte2cachemode_tbl[8] = { 
	[__pte2cm_idx(_PAGE_PWT | _PAGE_PCD | _PAGE_PAT)] = _PAGE_CACHE_MODE_UC,

};



/* Check that the write-protect PAT entry is set for write-protect */

/*

 * Check that the write-protect PAT entry is set for write-protect.

 * To do this without making assumptions how PAT has been set up (Xen has

 * another layout than the kernel), translate the _PAGE_CACHE_MODE_WP cache

 * mode via the __cachemode2pte_tbl[] into protection bits (those protection

 * bits will select a cache mode of WP or better), and then translate the

 * protection bits back into the cache mode using __pte2cm_idx() and the

 * __pte2cachemode_tbl[] array. This will return the really used cache mode.

 */

bool x86_has_pat_wp(void)

{

	return __pte2cachemode_tbl[_PAGE_CACHE_MODE_WP] == _PAGE_CACHE_MODE_WP;

	uint16_t prot = __cachemode2pte_tbl[_PAGE_CACHE_MODE_WP];



	return __pte2cachemode_tbl[__pte2cm_idx(prot)] == _PAGE_CACHE_MODE_WP;

}



enum page_cache_mode pgprot2cachemode(pgprot_t pgprot)