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Message-ID: <20240710160655.3402786-9-alexander.shishkin@linux.intel.com>
Date: Wed, 10 Jul 2024 19:06:44 +0300
From: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To: Andy Lutomirski <luto@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>,
Peter Zijlstra <peterz@...radead.org>,
Ard Biesheuvel <ardb@...nel.org>,
"Paul E. McKenney" <paulmck@...nel.org>,
Josh Poimboeuf <jpoimboe@...nel.org>,
Xiongwei Song <xiongwei.song@...driver.com>,
Xin Li <xin3.li@...el.com>,
"Mike Rapoport (IBM)" <rppt@...nel.org>,
Brijesh Singh <brijesh.singh@....com>,
Michael Roth <michael.roth@....com>,
Tony Luck <tony.luck@...el.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Alexey Kardashevskiy <aik@....com>
Cc: Jonathan Corbet <corbet@....net>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Sohil Mehta <sohil.mehta@...el.com>,
Ingo Molnar <mingo@...nel.org>,
Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
Daniel Sneddon <daniel.sneddon@...ux.intel.com>,
Kai Huang <kai.huang@...el.com>,
Sandipan Das <sandipan.das@....com>,
Breno Leitao <leitao@...ian.org>,
Rick Edgecombe <rick.p.edgecombe@...el.com>,
Yian Chen <yian.chen@...el.com>,
Alexei Starovoitov <ast@...nel.org>,
Hou Tao <houtao1@...wei.com>,
Juergen Gross <jgross@...e.com>,
Vegard Nossum <vegard.nossum@...cle.com>,
Kees Cook <kees@...nel.org>,
Eric Biggers <ebiggers@...gle.com>,
Jason Gunthorpe <jgg@...pe.ca>,
"Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Luis Chamberlain <mcgrof@...nel.org>,
Yuntao Wang <ytcoode@...il.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Tejun Heo <tj@...nel.org>,
Changbin Du <changbin.du@...wei.com>,
Huang Shijie <shijie@...amperecomputing.com>,
Geert Uytterhoeven <geert+renesas@...der.be>,
Namhyung Kim <namhyung@...nel.org>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org,
linux-efi@...r.kernel.org
Subject: [PATCH v4 08/16] x86/vsyscall: Reorganize the #PF emulation code
From: Sohil Mehta <sohil.mehta@...el.com>
Separate out the actual vsyscall emulation from the page fault specific
handling in preparation for the upcoming #GP fault emulation.
No functional change intended.
Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
---
arch/x86/entry/vsyscall/vsyscall_64.c | 42 +++++++++++++++------------
arch/x86/include/asm/vsyscall.h | 8 ++---
arch/x86/mm/fault.c | 2 +-
3 files changed, 29 insertions(+), 23 deletions(-)
diff --git a/arch/x86/entry/vsyscall/vsyscall_64.c b/arch/x86/entry/vsyscall/vsyscall_64.c
index 2fb7d53cf333..e89d7d83a594 100644
--- a/arch/x86/entry/vsyscall/vsyscall_64.c
+++ b/arch/x86/entry/vsyscall/vsyscall_64.c
@@ -112,30 +112,13 @@ static bool write_ok_or_segv(unsigned long ptr, size_t size)
}
}
-bool emulate_vsyscall(unsigned long error_code,
- struct pt_regs *regs, unsigned long address)
+static bool __emulate_vsyscall(struct pt_regs *regs, unsigned long address)
{
unsigned long caller;
int vsyscall_nr, syscall_nr, tmp;
long ret;
unsigned long orig_dx;
- /* Write faults or kernel-privilege faults never get fixed up. */
- if ((error_code & (X86_PF_WRITE | X86_PF_USER)) != X86_PF_USER)
- return false;
-
- if (!(error_code & X86_PF_INSTR)) {
- /* Failed vsyscall read */
- if (vsyscall_mode == EMULATE)
- return false;
-
- /*
- * User code tried and failed to read the vsyscall page.
- */
- warn_bad_vsyscall(KERN_INFO, regs, "vsyscall read attempt denied -- look up the vsyscall kernel parameter if you need a workaround");
- return false;
- }
-
/*
* No point in checking CS -- the only way to get here is a user mode
* trap to a high address, which means that we're in 64-bit user code.
@@ -270,6 +253,29 @@ bool emulate_vsyscall(unsigned long error_code,
return true;
}
+bool emulate_vsyscall_pf(unsigned long error_code, struct pt_regs *regs,
+ unsigned long address)
+{
+ /* Write faults or kernel-privilege faults never get fixed up. */
+ if ((error_code & (X86_PF_WRITE | X86_PF_USER)) != X86_PF_USER)
+ return false;
+
+ if (!(error_code & X86_PF_INSTR)) {
+ /* Failed vsyscall read */
+ if (vsyscall_mode == EMULATE)
+ return false;
+
+ /*
+ * User code tried and failed to read the vsyscall page.
+ */
+ warn_bad_vsyscall(KERN_INFO, regs,
+ "vsyscall read attempt denied -- look up the vsyscall kernel parameter if you need a workaround");
+ return false;
+ }
+
+ return __emulate_vsyscall(regs, address);
+}
+
/*
* A pseudo VMA to allow ptrace access for the vsyscall page. This only
* covers the 64bit vsyscall page now. 32bit has a real VMA now and does
diff --git a/arch/x86/include/asm/vsyscall.h b/arch/x86/include/asm/vsyscall.h
index 472f0263dbc6..214977f4fa11 100644
--- a/arch/x86/include/asm/vsyscall.h
+++ b/arch/x86/include/asm/vsyscall.h
@@ -14,12 +14,12 @@ extern void set_vsyscall_pgtable_user_bits(pgd_t *root);
* Called on instruction fetch fault in vsyscall page.
* Returns true if handled.
*/
-extern bool emulate_vsyscall(unsigned long error_code,
- struct pt_regs *regs, unsigned long address);
+extern bool emulate_vsyscall_pf(unsigned long error_code,
+ struct pt_regs *regs, unsigned long address);
#else
static inline void map_vsyscall(void) {}
-static inline bool emulate_vsyscall(unsigned long error_code,
- struct pt_regs *regs, unsigned long address)
+static inline bool emulate_vsyscall_pf(unsigned long error_code,
+ struct pt_regs *regs, unsigned long address)
{
return false;
}
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index e6c469b323cc..44e2d1ef4128 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1318,7 +1318,7 @@ void do_user_addr_fault(struct pt_regs *regs,
* to consider the PF_PK bit.
*/
if (is_vsyscall_vaddr(address)) {
- if (emulate_vsyscall(error_code, regs, address))
+ if (emulate_vsyscall_pf(error_code, regs, address))
return;
}
#endif
--
2.43.0
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