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Commit 7a2fda4e authored by Kevin Brodsky's avatar Kevin Brodsky Committed by Gagan Malvi
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FROMLIST: [PATCH v3 1/3] arm64: compat: Split the sigreturn trampolines and... 

FROMLIST: [PATCH v3 1/3] arm64: compat: Split the sigreturn trampolines and kuser helpers (C sources)

(cherry picked from url http://lkml.iu.edu/hypermail/linux/kernel/1709.1/01901.html

)

AArch32 processes are currently installed a special [vectors] page that
contains the sigreturn trampolines and the kuser helpers, at the fixed
address mandated by the kuser helpers ABI.

Having both functionalities in the same page has become problematic,
because:

* It makes it impossible to disable the kuser helpers (the sigreturn
  trampolines cannot be removed), which is possible on arm.

* A future 32-bit vDSO would provide the sigreturn trampolines itself,
  making those in [vectors] redundant.

This patch addresses the problem by moving the sigreturn trampolines to
a separate [sigpage] page, mirroring [sigpage] on arm.

Even though [vectors] has always been a misnomer on arm64/compat, as
there is no AArch32 vector there (and now only the kuser helpers),
its name has been left unchanged, for compatibility with arm (there
are reports of software relying on [vectors] being there as the last
mapping in /proc/maps).

mm->context.vdso used to point to the [vectors] page, which is
unnecessary (as its address is fixed). It now points to the [sigpage]
page (whose address is randomized like a vDSO).

Signed-off-by: default avatarKevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: default avatarMark Salyzyn <salyzyn@android.com>
Bug: 9674955
Bug: 63737556
Bug: 20045882
Change-Id: I52a56ea71d7326df8c784f90eb73b5c324fe9d20
Signed-off-by: default avatarkhusika <khusikadhamar@gmail.com>
Signed-off-by: default avatarTheSync <repo-sync@outlook.com>
parent f3d17156

arch/arm/include/asm/cp15.h

+0 −2
Original line number Diff line number Diff line
@@ -67,8 +67,6 @@ 
#define BPIALL				__ACCESS_CP15(c7, 0, c5, 6)

#define ICIALLU				__ACCESS_CP15(c7, 0, c5, 0)



#define CNTVCT				__ACCESS_CP15_64(1, c14)



extern unsigned long cr_alignment;	/* defined in entry-armv.S */



static inline unsigned long get_cr(void)

arch/arm/vdso/vgettimeofday.c

+2 −3
Original line number Diff line number Diff line
@@ -18,9 +18,9 @@ 
#include <linux/compiler.h>

#include <linux/hrtimer.h>

#include <linux/time.h>

#include <asm/arch_timer.h>

#include <asm/barrier.h>

#include <asm/bug.h>

#include <asm/cp15.h>

#include <asm/page.h>

#include <asm/unistd.h>

#include <asm/vdso_datapage.h>
@@ -123,8 +123,7 @@ static notrace u64 get_ns(struct vdso_data *vdata) 
	u64 cycle_now;

	u64 nsec;



	isb();

	cycle_now = read_sysreg(CNTVCT);

	cycle_now = arch_counter_get_cntvct();



	cycle_delta = (cycle_now - vdata->cs_cycle_last) & vdata->cs_mask;

arch/arm64/include/asm/processor.h

+2 −2
Original line number Diff line number Diff line
@@ -70,9 +70,9 @@ 


#define STACK_TOP_MAX		TASK_SIZE_64

#ifdef CONFIG_COMPAT

#define AARCH32_VECTORS_BASE	0xffff0000

#define AARCH32_KUSER_HELPERS_BASE 0xffff0000

#define STACK_TOP		(test_thread_flag(TIF_32BIT) ? \

				AARCH32_VECTORS_BASE : STACK_TOP_MAX)

				AARCH32_KUSER_HELPERS_BASE : STACK_TOP_MAX)

#else

#define STACK_TOP		STACK_TOP_MAX

#endif /* CONFIG_COMPAT */

arch/arm64/include/asm/signal32.h

+0 −2
Original line number Diff line number Diff line
@@ -20,8 +20,6 @@ 
#ifdef CONFIG_COMPAT

#include <linux/compat.h>



#define AARCH32_KERN_SIGRET_CODE_OFFSET	0x500



int compat_setup_frame(int usig, struct ksignal *ksig, sigset_t *set,

		       struct pt_regs *regs);

int compat_setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,

arch/arm64/include/asm/vdso_datapage.h

+0 −1
Original line number Diff line number Diff line
@@ -38,7 +38,6 @@ struct vdso_data { 
	__u32 tz_minuteswest;	/* Whacky timezone stuff */

	__u32 tz_dsttime;

	__u32 use_syscall;

	__u32 hrtimer_res;

};



#endif /* !__ASSEMBLY__ */